Probing bursty star formation by cross-correlating extragalactic background light and galaxy surveys [GA]

http://arxiv.org/abs/2305.08847


Understanding the star formation rate (SFR) variability and how it depends on physical properties of galaxies is important for developing and testing the theory of galaxy formation. We investigate how statistical measurements of the extragalactic background light (EBL) can shed light on this topic and complement traditional methods based on observations of individual galaxies. Using semi-empirical models of galaxy evolution and SFR indicators sensitive to different star formation timescales (e.g., H$\alpha$ and UV continuum luminosities), we show that the SFR variability, quantified by the joint probability distribution of the SFR indicators (i.e., the bivariate conditional luminosity function), can be characterized as a function of galaxy mass and redshift through the cross-correlation between deep, near-infrared maps of the EBL and galaxy distributions. As an example, we consider combining upcoming SPHEREx maps of the EBL with galaxy samples from Rubin/LSST. We demonstrate that their cross-correlation over a sky fraction of $f_\mathrm{sky}\sim0.5$ can constrain the joint SFR indicator distribution at high significance up to $z\sim2.5$ for mass-complete samples of galaxies down to $M_{*}\sim10^9\,M_{\odot}$. These constraints not only allow models of different SFR variability to be distinguished, but also provide unique opportunities to investigate physical mechanisms that require large number statistics such as environmental effects. The cross-correlations investigated illustrate the power of combining cosmological surveys to extract information inaccessible from each data set alone, while the large galaxy populations probed capture ensemble-averaged properties beyond the reach of targeted observations towards individual galaxies.

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G. Sun, A. Lidz, A. Faisst, et. al.
Tue, 16 May 23
62/83

Comments: 12 pages, 7 figures, submitted to MNRAS; comments welcome

Identification of molecular clouds in emission maps: a comparison between methods in the \ce{^{13}CO}/\ce{C^{18}O} ($J=3-2$) Heterodyne Inner Milky Way Plane Survey [GA]

http://arxiv.org/abs/2305.07874


The growing range of automated algorithms for the identification of molecular clouds and clumps in large observational datasets has prompted the need for the direct comparison of these procedures. However, these methods are complex and testing for biases is often problematic: only a few of them have been applied to the same data set or calibrated against a common standard. We compare the Fellwalker method, a widely used watershed algorithm, to the more recent Spectral Clustering for Interstellar Molecular Emission Segmentation (SCIMES). SCIMES overcomes sensitivity and resolution biases that plague many friends-of-friends algorithms by recasting cloud segmentation as a clustering problem. Considering the \ce{^{13}CO}/\ce{C^{18}O} ($J = 3 – 2$) Heterodyne Inner Milky Way Plane Survey (CHIMPS) and the CO High-Resolution Survey (COHRS), we investigate how these two different approaches influence the final cloud decomposition. Although the two methods produce largely similar statistical results over the CHIMPS dataset, FW appears prone to over-segmentation, especially in crowded fields where gas envelopes around dense cores are identified as adjacent, distinct objects. FW catalogue also includes a number of fragmented clouds that appear as different objects in a line-of-sight projection. In addition, cross-correlating the physical properties of individual sources between catalogues is complicated by different definitions, numerical implementations, and design choices within each method, which make it very difficult to establish a one-to-one correspondence between the sources.

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R. Rani, T. Moore, D. Eden, et. al.
Tue, 16 May 23
64/83

Comments: accepted MNRAS

Tidal Spin-up of Black Hole Progenitor Stars [HEAP]

http://arxiv.org/abs/2305.08356


Gravitational wave observations indicate the existence of merging black holes (BHs) with high spin ($a\gtrsim0.3$), whose formation pathways are still an open question. A possible way to form those binaries is through the tidal spin-up of a Wolf-Rayet (WR) star by its BH companion. In this work, we investigate this scenario by directly calculating the tidal excitation of oscillation modes in WR star models, determining the tidal spin-up rate, and integrating the coupled spin-orbit evolution for WR-BH binaries. We find that for short-period orbits and massive WR stars, the tidal interaction is mostly contributed by standing gravity modes, in contrast to Zahn’s model of travelling waves which is frequently assumed in the literature. The standing modes are less efficiently damped than traveling waves, meaning that prior estimates of tidal spin-up may be overestimated. We show that tidal synchronization is rarely reached in WR-BH binaries, and the resulting BH spins have $a \lesssim 0.4$ for all but the shortest period ($P_{\rm orb} ! \lesssim 0.5 \, {\rm d}$) binaries. Tidal spin-up in lower-mass systems is more efficient, providing an anti-correlation between the mass and spin of the BHs, which could be tested in future gravitational wave data. Non-linear damping processes are poorly understood but may allow for more efficient tidal spin-up. We also discuss a new class of gravito-thermal modes that appear in our calculations.

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L. Ma and J. Fuller
Tue, 16 May 23
68/83

Comments: Revised after referee report from ApJ. Comments welcome

The most luminous blue quasars at 3.0<z<3.3 – III. LBT spectra and accretion parameters [GA]

http://arxiv.org/abs/2305.07699


We present the analysis of the rest frame ultraviolet and optical spectra of 30 bright blue quasars at $z\sim3$, selected to examine the suitability of AGN as cosmological probes. In our previous works, we found an unexpectedly high fraction ($\approx 25 \%$) of X-ray weak quasars in the sample. The latter sources also display a flatter UV continuum and a broader and fainter CIV profile in the archival UV data with respect to their X-ray normal counterparts. Here we present new observations with the LBT in both the $zJ$ (rest-frame $\simeq$2300-3100 $\rm \mathring{A}$) and the $K_S$ ($\simeq$4750-5350 $\rm \mathring{A}$) bands. We estimated black hole masses ($M_{\rm BH}$) and Eddington ratios ($\lambda_{\rm Edd}$) from the from the H$\beta$ and MgII emission lines, finding that our $z\sim3$ quasars are on average highly accreting ($\langle \lambda_{\rm Edd} \rangle\simeq 1.2$ and $\langle M_{\rm BH} \rangle\simeq 10^{9.7}M_\odot$), with no difference in $\lambda_{\rm Edd}$ or $M_{\rm BH}$ between X-ray weak and X-ray normal quasars. From the $zJ$ spectra, we derive flux and equivalent width of MgII and FeII, finding that X-ray weak quasars display higher FeII/MgII ratios with respect to typical quasars. FeII/MgII ratios of X-ray normal quasars are instead consistent with other estimates up to $z\simeq6.5$, corroborating the idea of already chemically mature BLRs at early cosmic time. From the $K_S$ spectra, we find that all the X-ray weak quasars present generally weaker [OIII] emission (EW<10 $\rm \mathring{A}$) than the normal ones. The sample as a whole, however, abides by the known X-ray/[OIII] luminosity correlation, hence the different [OIII] properties are likely due to an intrinsically weaker [OIII] emission in X-ray weak objects, associated to the shape of the spectral energy distribution. We interpret these results in the framework of accretion-disc winds.

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B. Trefoloni, E. Lusso, E. Nardini, et. al.
Tue, 16 May 23
69/83

Comments: 25 pages, 17 figures, Accepted for publication on Astronomy & Astrophysics

Observed Dust Surface Density Across Cosmic Times [GA]

http://arxiv.org/abs/2305.07743


Our ability to interpret observations of galaxies and trace their stellar, gas, and dust content over cosmic time critically relies on our understanding of how the dust abundance and properties vary with environment. Here, we compute the dust surface density across cosmic times to put novel constraints on simulations of the build-up of dust. We provide observational estimates of the dust surface density consistently measured through depletion methods across a wide range of environments, going from the Milky Way up to $z=5.5$ galaxies. These conservative measurements provide complementary estimates to extinction-based observations. In addition, we introduce the dust surface density distribution function — in analogy with the cold gas column density distribution functions. We fit a power law of the form: $\log f( \Sigma_{\rm Dust})=-1.92 \times \log \Sigma_{\rm Dust} – 3.65$ which proves slightly steeper than for neutral gas and metal absorbers. This observed relation, which can be computed by simulations predicting resolved dust mass functions through 2D projection, provides new constraints on modern dust models.

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C. Péroux, A. Cia and J. Howk
Tue, 16 May 23
70/83

Comments: 11 pages. Accepted for publication in MNRAS

Fast rotating Blue Stragglers prefer loose clusters [SSA]

http://arxiv.org/abs/2305.08478


Blue stragglers are anomalously luminous core hydrogen-burning stars formed through mass-transfer in binary/triple systems and stellar collisions. Their physical and evolutionary properties are largely unknown and unconstrained. Here we analyze 320 high-resolution spectra of blue stragglers collected in eight galactic globular clusters with different structural characteristics and show evidence that the fraction of fast rotating blue stragglers (with rotational velocities larger than 40 km/s) increases for decreasing central density of the host system. This trend suggests that fast spinning blue stragglers prefer low-density environments and promises to open an unexplored route towards understanding the evolutionary processes of these stars. Since large rotation rates are expected in the early stages of both formation channels, our results provide direct evidence for recent blue straggler formation activity in low-density environments and put strong constraints on the timescale of the collisional blue straggler slow-down processes.

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F. Ferraro, A. Mucciarelli, B. Lanzoni, et. al.
Tue, 16 May 23
75/83

Comments: Published in Nature Communications

The Two Quasi-Static Limits of Aether Scalar Tensor Theory [CL]

http://arxiv.org/abs/2305.07742


One of the aims of Aether Scalar Tensor Theory (AeST) is to reproduce the successes of Modified Newtonian Dynamics (MOND) on galactic scales. Indeed, the quasi-static limit of AeST can achieve precisely this, assuming that the vector field $\vec{A}$ vanishes. However, this assumption of a vanishing vector field is often inconsistent. Here, we show how to correctly take into account the vector field and find that the quasi-static limit depends on a model parameter $m_\times$. In the limit $m_\times \to 0$, one recovers the quasi-static limit with a vanishing vector field. In particular, one finds a two-field version of MOND. In the opposite limit, $m_\times \to \infty$, one finds a single-field version of MOND. We show that, in practice, much of the phenomenology of the quasi-static limit depends only very little on the value of $m_\times$. Still, for some observational tests, such as those involving wide binaries, $m_\times$ has percent-level effects that may be important.

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T. Mistele
Tue, 16 May 23
80/83

Comments: 24 pages, 4 figures

The X-ray binaries in M83: will any of them form gravitational wave sources for LIGO/VIRGO/KAGRA? [HEAP]

http://arxiv.org/abs/2305.08640


There are 214 X-ray point-sources ($L_{\rm X}>10^{35} \mathrm{erg/s}$) identified as X-ray binaries (XRBs) in the nearby spiral galaxy M83. Since XRBs are powered by accretion onto a neutron star or a black hole from a companion/donor star these systems are promising progenitors of merging double compact objects (DCOs): black hole – black hole (BH-BH), black hole – neutron star (BH-NS), or neutron star – neutron star (NS-NS) systems. The connection (i.e. XRBs evolving into DCOs) may provide some hints to the yet unanswered question: what is the origin of the LIGO/Virgo/KAGRA mergers? Available observations do not allow to determine what will be the final fate of the XRBs observed in M83. Yet, we can use evolutionary model of isolated binaries to reproduce the population of XRBs in M83 by matching model XRBs numbers/types/luminosities to observations. Knowing the detailed properties of M83 model XRBs (donor/accretor masses, their evolutionary ages and orbits) we follow their evolution to the death of donor stars to check whether any merging DCOs are formed. Although all merging DCOs in our isolated binary evolution model go through the XRB phase (defined as reaching X-ray luminosity from RLOF/wind accretion onto NS/BH above $10^{35}$ erg/s), only very few XRBs evolve to form merging (in Hubble time) DCOs. For M83 with its solar-like metallicity stars and continiuous star-formation we find that only $\sim 1-2\%$ of model XRBs evolve into merging DCOs depending on the adopted evolutionary physics. This is caused by (i) merger of donor star with compact object during common envelope phase, (ii) binary disruption at the supernova explosion of donor star, (iii) formation of a DCO on a wide orbit (merger time longer than Hubble time).

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I. Kotko and K. Belczynski
Tue, 16 May 23
82/83

Comments: 11 pages, 1 figure, submitted to A&A

UV signatures of magnetar formation and their crucial role for Gravitational Wave detection [HEAP]

http://arxiv.org/abs/2305.07761


The emission from shock breakouts (SBOs) represents the earliest electromagnetic (EM) signal emitted by cataclysmic events involving the formation or the merger of neutron stars (NSs). As such, SBOs carry unique information on the structure of their progenitors and on the explosion energy. The characteristic~SBO emission is expected in the UV range, and its detection is one of the key targets of~the ULTRASAT satellite. Among SBO sources, we focus on a specific class involving the formation of fast spinning magnetars in the core-collapse (CC) of massive stars. Fast spinning magnetars are expected to produce a specific signature in the early UV supernova light curve, powered by the extra spin energy quickly released by the NS. Moreover, they are considered as optimal candidates for the emission of long-transient gravitational wave (GW) signals, the detection of which requires early EM triggers to boost the sensitivity of dedicated GW search pipelines. We calculate early supernova UV light curves in the presence of a magnetar central engine, as a function of the explosion energy, ejecta mass and magnetar parameters. We then estimate the ULTRASAT detection horizon (z < 0.15) as a function of the same physical parameters, and the overall expected detection rate finding that magnetar-powered SBOs may represent up to 1/5 of the total events detected by ULTRASAT. Moreover, at the expected sensitivity of the LIGO/Virgo/Kagra O5 science run, one such event occurring within 5 Mpc will providean ideal trigger for a GW long transient search. Future GW detectors like the Einstein Telescope will push the horizon for joint EM-GW detections to 35-40 Mpc.

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S. Menon, D. Guetta and S. Dall’Osso
Tue, 16 May 23
83/83

Comments: 7 pages, 3 figures. Submitted to ApJ

GMP-selected dual and lensed AGNs: selection function and classification based on near-IR colors and resolved spectra from VLT/ERIS, KECK/OSIRIS, and LBT/LUCI [GA]

http://arxiv.org/abs/2305.07396


The Gaia-Multi-Peak (GMP) technique can identify large numbers of dual or lensed active galactic nuclei (AGN) candidates at sub-arcsec separation, allowing us to study both multiple super-massive black holes (SMBH) in the same galaxy and rare, compact lensed systems. The observed samples can be used to test the predictions of the models of SMBH merging once 1) the selection function of the GMP technique is known, and 2) each system has been classified as dual AGN, lensed AGN, or AGN/star alignment. Here we show that the GMP selection is very efficient for separations above 0.15″ when the secondary (fainter) object has magnitude G<20.5. We present the spectroscopic classification of five GMP candidates using VLT/ERIS and Keck/OSIRIS, and compare them with the classifications obtained from: a) the near-IR colors of 7 systems obtained with LBT/LUCI, and b) the analysis of the total, spatially-unresolved spectra. We conclude that colors and integrated spectra can already provide reliable classifications of many systems. Finally, we summarize the 14 confirmed dual AGNs at z>0.5 selected by the GMP technique, and compare this sample with other such systems from the literature, concluding that GMP can provide a large number of confirmed dual AGNs at separations below 7 kpc.

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F. Mannucci, M. Scialpi, A. Ciurlo, et. al.
Mon, 15 May 23
1/53

Comments: 14 pages, submitted. Comments welcome

The Spitzer Extragalactic Representative Volume Survey and DeepDrill extension: clustering of near-infrared galaxies [CEA]

http://arxiv.org/abs/2305.07464


We have measured the angular auto-correlation function of near-infrared galaxies in SERVS+DeepDrill, the Spitzer Extragalactic Representative Volume Survey and its follow-up survey of the Deep Drilling Fields, in three large fields totalling over 20 sq. deg on the sky, observed in two bands centred on 3.6 and 4.5 micron. We performed this analysis on the full sample as well as on sources selected by [3.6]-[4.5] colour in order to probe clustering for different redshift regimes. We estimated the spatial correlation strength as well, using the redshift distribution from S-COSMOS with the same source selection. The strongest clustering was found for our bluest subsample, with z~0.7, which has the narrowest redshift distribution of all our subsamples. We compare these estimates to previous results from the literature, but also to estimates derived from mock samples, selected in the same way as the observational data, using deep light-cones generated from the SHARK semi-analytical model of galaxy formation. For all simulated (sub)samples we find a slightly steeper slope than for the corresponding observed ones, but the spatial clustering length is comparable in most cases.

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E. Kampen, M. Lacy, D. Farrah, et. al.
Mon, 15 May 23
2/53

Comments: 20 pages, 15 figures, 6 tables, accepted for publication in MNRAS

Large-scale Velocity-coherent Filaments in the SEDIGISM Survey: Association with Spiral Arms and Fraction of Dense Gas [GA]

http://arxiv.org/abs/2305.07353


Context. Filamentary structures in the interstellar medium are closely related to star formation. Dense gas mass fraction (DGMF) or clump formation efficiency in large-scale filaments possibly determine their hosting star formation activities. Aims. We aim to automatically identify large-scale filaments, characterize them, investigate their association with Galactic structures, and study their DGMFs. Methods. We use a modified minimum spanning tree (MST) algorithm to chain parsec-scale 13CO clumps previously extracted from the SEDIGISM (Structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium) survey. The MST connects nodes in a graph such that the sum of edge lengths is minimum. Modified MST also ensures velocity coherence between nodes, so the identified filaments are coherent in position-position-velocity (PPV) space. Results. We generate a catalog of 88 large-scale ($>10pc$) filaments in the inner Galactic plane (with $-60^\circ < l < 18^\circ and $|b| < 0.5^\circ$). These SEDIGISM filaments are larger and less dense than MST filaments previously identified from the BGPS and ATLASGAL surveys. We find that eight of the filaments run along spiral arms and can be regarded as “bones” of the Milky Way. We also find three bones associated with the Local Spur in PPV space. By compiling 168 large-scale filaments with available DGMF across the Galaxy, an order of magnitude more than previously investigated, we find that DGMFs do not correlate with Galactic location, but bones have higher DGMFs than other filaments.

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Y. Ge, K. Wang, A. Duarte-Cabral, et. al.
Mon, 15 May 23
8/53

Comments: Accepted for publication in A&A. 30 pages, 8 figures, 3 tables

Spectral age distribution for radio-loud active galaxies in the XMM-LSS field [GA]

http://arxiv.org/abs/2305.07561


Jets of energetic particles, as seen in FR type-I and FR type-II sources, ejected from the center of Radio-Loud AGN affect the sources surrounding intracluster medium/intergalactic medium. Placing constraints on the age of such sources is important in order to measure the jet powers and determine the effects on feedback. To evaluate the age of these sources using spectral age models, we require high-resolution multi-wavelength data. The new sensitive and high-resolution MIGHTEE survey of the XMM-LSS field along with data from the Low Frequency Array (LOFAR) and the Giant Metrewave Radio Telescope (GMRT) provide data taken at different frequencies with similar resolution, which enables us to determine the spectral age distribution for radio loud AGN in the survey field. In this study we present a sample of 28 radio galaxies with their best fitting spectral age distribution analyzed using the Jaffe-Perola (JP) model on a pixel-by-pixel basis. Fits are generally good and objects in our sample show maximum ages within the range of 2.8 Myr to 115 Myr with a median of 8.71 Myr. High-resolution maps over a range of frequencies are required to observe detailed age distributions for small sources and high-sensitivity maps will be needed in order to observe fainter extended emission. We do not observe any correlation between the total physical size of the sources and their age and we speculate both dynamical models and the approach to spectral age analysis may need some modification to account for our observations.

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S. Pinjarkar, M. Hardcastle, J. Harwood, et. al.
Mon, 15 May 23
10/53

Comments: 20 pages, 9 figures

Spectroscopic substellar initial mass function of NGC 2244 [SSA]

http://arxiv.org/abs/2305.07158


We aim at characterizing the low-mass (sub)stellar population of the central portion (2.4 pc$^2$) of the $\sim$2 Myr old cluster NGC 2244 using near infrared spectroscopy. By studying this cluster, characterized by a low stellar density and numerous OB stars, we aim at exploring the effect that OB stars may have on the production of BDs. We obtain near infrared HK spectroscopy of 85 faint candidate members of NGC 2244. We derive the spectral type and extinction by comparison with spectral templates. We evaluate cluster membership using three gravity-sensitive spectral indices based on the shape of the $H$-band. Furthermore, we evaluate the infrared excess from Spitzer of all the candidate members of the cluster. Finally, we estimate the mass of all the candidate members of the cluster and derive the initial mass function, star-to-BD number ratio and disk fraction. The initial mass function is well represented by a power law ($dN/dM \propto M^{-\alpha}$) below 0.4 $M_\odot$, with a slope $\alpha$ = 0.7-1.1 depending on the fitted mass range. We calculate a star-to-BD number ratio of 2.2-2.8. We find the low-mass population of NGC 2244 to be consistent with nearby star-forming regions, although it is at the high-end of BD production. We find BDs in NGC 2244 to be on average closer to OB stars than to low-mass stars, which could potentially be the first evidence of OB stars affecting the formation of BDs. We find a disk fraction of all the members with spectral type later than K0 of 39$\pm$9% which is lower than typical values found in nearby star-forming regions of similar ages.

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V. Almendros-Abad, K. Mužić, H. Bouy, et. al.
Mon, 15 May 23
12/53

Comments: Accepted by A&A, KMOS spectroscopic data will be made public on Vizier upon publication

First detection of deuterated methylidyne (CD) in the interstellar medium [GA]

http://arxiv.org/abs/2305.07143


While the abundance of elemental deuterium is relatively low (D/H ~ a few 1E-5), orders of magnitude higher D/H abundance ratios have been found for many interstellar molecules, enhanced by deuterium fractionation. In cold molecular clouds (T < 20K) deuterium fractionation is driven by the H2D+ ion, whereas at higher temperatures (T > 20-30K) gas-phase deuteration is controlled by reactions with CH2D+ and C2HD+. While the role of H2D+ in driving cold interstellar deuterium chemistry is well understood, thanks to observational constraints from direct measurements of H2D+, deuteration stemming from CH2D+ is far less understood, caused by the absence of direct observational constraints of its key ions. Therefore, making use of chemical surrogates is imperative for exploring deuterium chemistry at intermediate temperatures. Formed at an early stage of ion-molecule chemistry, directly from the dissociative recombination of CH3+ (CH2D+), CH (CD) is an ideal tracer for investigating deuterium substitution initiated by reactions with CH2D+. This paper reports the first detection of CD in the interstellar medium, carried out using the APEX 12m telescope toward the widely studied low-mass protostellar system IRAS 16293-2422. Gas-phase chemical models reproducing the observed CD/CH abundance ratio of 0.016 suggests that it reflects `warm deuterium chemistry’ (which ensues in moderately warm conditions of the interstellar medium) and illustrates the potential use of the CD/CH ratio in constraining the gas temperatures of the envelope gas clouds it probes.

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A. Jacob, K. Menten, F. Wyrowski, et. al.
Mon, 15 May 23
14/53

Comments: Accepted for publication in Astronomy & Astrophysics (14 pages, 11 figures and 7 tables including Appendix)

NIKA2 Cosmological Legacy Survey: Survey Description and Galaxy Number Counts [GA]

http://arxiv.org/abs/2305.07054


Aims. Deep millimeter surveys are necessary to probe the dust-obscured galaxies at high redshift. We conducted a large observing program at 1.2 and 2 mm with the NIKA2 camera installed on the IRAM 30-meter telescope. This NIKA2 Cosmological Legacy Survey (N2CLS) covers two emblematic fields: GOODS-N and COSMOS. We introduce the N2CLS survey and present new 1.2 and 2 mm number count measurements based on the tiered N2CLS observations from October 2017 to May 2021.
Methods. We develop an end-to-end simulation that combines an input sky model with the instrument noise and data reduction pipeline artifacts. This simulation is used to compute the sample purity, flux boosting, pipeline transfer function, completeness, and effective area of the survey. We used the 117 deg$^2$ SIDES simulations as the sky model, which include the galaxy clustering. Our formalism allows us to correct the source number counts to obtain galaxy number counts, the difference between the two being due to resolution effects caused by the blending of several galaxies inside the large beam of single-dish instruments.
Results. The N2CLS-May2021 survey reaches an average 1-$\sigma$ noise level of 0.17 and 0.048 mJy on GOODS-N over 159 arcmin$^2$, and 0.46 and 0.14 mJy on COSMOS over 1010 arcmin$^2$, at 1.2 and 2 mm, respectively. For a purity threshold of 80%, we detect 120 and 67 sources in GOODS-N and 195 and 76 sources in COSMOS, at 1.2 and 2 mm, respectively. Our measurement connects the bright single-dish to the deep interferometric number counts. After correcting for resolution effects, our results reconcile the single-dish and interferometric number counts and are further accurately compared with model predictions.

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L. Bing, M. Béthermin, G. Lagache, et. al.
Mon, 15 May 23
15/53

Comments: Accepted by A&A. 23 pages, 12 figures

On the nature of M31 gamma-ray halo in its relation to dark matter annihilation [HEAP]

http://arxiv.org/abs/2305.07590


The present work analyzes various aspects of M31 gamma-ray halo emission in its relation to annihilating dark matter (DM). The main aspect is the predicted effect of asymmetry of the intensity of emission due to inverse Compton scattering (ICS) of a possible population of relativistic electrons and positrons ($e^\pm$) in the galactic halo on starlight photons. This asymmetry is expected to exist around the major galactic axis, and arises due to anisotropy of the interstellar radiation field and the inclination of M31. ICS emission and its asymmetry were modeled by GALPROP code for the trial case of $e^\pm$ generated by annihilating weakly interacting massive particles (WIMPs) with various properties. The asymmetry was obtained to appear at photon energies above $\sim$ 0.1 MeV. Morphological and spectral properties of the asymmetry were studied in detail. Potential observational detection of the asymmetry may allow to infer the leptonic fraction in the emission generation mechanism, thus providing valuable inferences for understanding the nature of M31 gamma-ray halo emission. Specific asymmetry predictions were made for the recently claimed DM interpretation of the outer halo emission. The paper also studied the role of secondary — ICS and bremsstrahlung — emissions due to DM annihilation for that interpretation. And, finally, the latter was shown to be in significant tension with the recently derived WIMP constraints by radio data on M31.

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A. Egorov
Mon, 15 May 23
16/53

Comments: 15 pages, 5 figures, 4 tables, submitted to Phys. Rev. D

Post-Starburst Properties of Post-Merger Galaxies [GA]

http://arxiv.org/abs/2305.07474


Post-starburst galaxies (PSBs) are transition galaxies showing evidence of recent rapid star formation quenching. To understand the role of galaxy mergers in triggering quenching, we investigate the incidence of PSBs and resolved PSB properties in post-merger galaxies using both SDSS single-fiber spectra and MaNGA resolved IFU spectra. We find post-mergers have a PSB excess of 10 – 20 times that relative to their control galaxies using single-fiber PSB diagnostics. A similar excess of ~ 19 times is also found in the fraction of central (C)PSBs and ring-like (R)PSBs in post-mergers using the resolved PSB diagnostic. However, 60% of the CPSBs + RPSBs in both post-mergers and control galaxies are missed by the single-fiber data. By visually inspecting the resolved PSB distribution, we find that the fraction of outside-in quenching is 7 times higher than inside-out quenching in PSBs in post-mergers while PSBs in control galaxies do not show large differences in these quenching directions. In addition, we find a marginal deficit of HI gas in PSBs relative to non-PSBs in post-mergers using the MaNGA-HI data. The excesses of PSBs in post-mergers suggest that mergers play an important role in triggering quenching. Resolved IFU spectra are important to recover the PSBs missed by single-fiber spectra. The excess of outside-in quenching relative to inside-out quenching in post-mergers suggests that AGN are not the dominant quenching mechanism in these galaxies, but that processes from the disk (gas inflows/consumption and stellar feedback) play a more important role.

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W. Li, P. Nair, K. Rowlands, et. al.
Mon, 15 May 23
17/53

Comments: Accepted in MNRAS on May 12 2023, 19 pages, 15 figures, 4 tables

Multi log-normal density structure in Cygnus-X molecular clouds: A fitting for N-PDF without power-law [GA]

http://arxiv.org/abs/2305.07094


We studied the H$_2$ column density probability distribution function (N-PDF) based on molecular emission lines using the Nobeyama 45-m Cygnus X CO survey data. Using the DENDROGRAM and SCIMES algorithms, we identified 124 molecular clouds in the $^{13}$CO data. From these identified molecular clouds, an N-PDF was constructed for 11 molecular clouds with an extent of more than 0.4 deg$^2$. From the fitting of the N-PDF, we found that the N-PDF could be well-fitted with one or two log-normal distributions. These fitting results provided an alternative density structure for molecular clouds from a conventional picture. We investigated the column density, dense molecular cloud cores, and radio continuum source distributions in each cloud and found that the N-PDF shape was less correlated with the star-forming activity over a whole cloud. Furthermore, we found that the log-normal N-PDF parameters obtained from the fitting showed two impressive features. First, the log-normal distribution at the low-density part had the same mean column density ($\sim$ 10$^{21.5}$ cm$^{-2}$) for almost all the molecular clouds. Second, the width of the log-normal distribution tended to decrease with an increasing mean density of the structures. These correlations suggest that the shape of the N-PDF reflects the relationship between the density and turbulent structure of the whole molecular cloud but is less affected by star-forming activities.

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T. Murase, T. Handa, R. Matsusaka, et. al.
Mon, 15 May 23
20/53

Comments: 14 pages, 7 Figures, Accepted in MNRAS

Insights from HST into Ultra-Massive Galaxies and Early-Universe Cosmology [CEA]

http://arxiv.org/abs/2305.07049


The early-science observations made by the James Webb Space Telescope (JWST) have revealed an excess of ultra-massive galaxy candidates that appear to challenge the standard cosmological model ($\Lambda$CDM). Here, we argue that any modifications to $\Lambda$CDM that can produce such ultra-massive galaxies in the early Universe would also affect the UV galaxy luminosity function (UV LF) inferred from the Hubble Space Telescope (HST). The UV LF covers the same redshifts ($z\approx 7-10$) and host-halo masses $(M_\mathrm{h}\approx 10^{10}-10^{12}\, M_\odot$) as the JWST candidates, but tracks star-formation rate rather than stellar mass. We consider beyond-$\Lambda$CDM power-spectrum enhancements and show that any departure large enough to reproduce the abundance of ultra-massive JWST candidates is in conflict with the HST data. Our analysis, therefore, severely disfavors a cosmological explanation for the JWST abundance problem. Looking ahead, we determine the maximum allowable stellar-mass function and provide projections for the high-$z$ UV LF given our constraints on cosmology from current HST data.

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N. Sabti, J. Muñoz and M. Kamionkowski
Mon, 15 May 23
22/53

Comments: 9 pages, 4 figures

Efficient radial migration by giant molecular clouds in the first several hundred Myr after the stellar birth [GA]

http://arxiv.org/abs/2305.07050


Stars in the Galactic disc, including the Solar system, have deviated from their birth orbits and have experienced radial mixing and vertical heating. By performing hydrodynamical simulations of a galactic disc, we investigate how much tracer particles, which are initially located in the disc to mimic newborn stars and the thin and thick disc stars, are displaced from initial near-circular orbits by gravitational interactions with giant molecular clouds (GMCs). To exclude the influence of other perturbers that can change the stellar orbits, such as spiral arms and the bar, we use an axisymmetric form for the entire galactic potential. First, we investigate the time evolution of the radial and vertical velocity dispersion $\sigma_R$ and $\sigma_z$ by comparing them with a power law relation of $\sigma \propto t^{\beta}$. Although the exponents $\beta$ decrease with time, they keep large values of 0.3 $\sim$ 0.6 for 1 Gyr, indicating fast and efficient disc heating. Next, we find that the efficient stellar scattering by GMCs also causes a change in angular momentum for each star and, therefore, radial migration. This effect is more pronounced in newborn stars than old disc stars; nearly 30 per cent of stars initially located on the galactic mid-plane move more than 1 kpc in the radial direction for 1 Gyr. The dynamical heating and radial migration drastically occur in the first several hundred Myr. As the amplitude of the vertical oscillation increases, the time spent in the galactic plane, where most GMCs are distributed, decreases, and the rate of an increase in the heating and migration slows down.

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Y. Fujimoto, S. Inutsuka and J. Baba
Mon, 15 May 23
29/53

Comments: 17 pages, 12 figures. Submitted to MNRAS. The simulation movie can be found at this https URL

How do supernova remnants cool? — I. Morphology, optical emission lines, and shocks [HEAP]

http://arxiv.org/abs/2305.07652


Supernovae (SNe) inject $\sim 10^{51}$ erg in the interstellar medium, thereby shocking and heating the gas. A substantial fraction of this energy is later lost via radiative cooling. We present a post-processing module for the FLASH code to calculate the cooling radiation from shock-heated gas using collisional excitation data from MAPPINGS V. When applying this tool to a simulated SN remnant (SNR), we find that most energy is emitted in the EUV. However, optical emission lines ($[$O III$]$, $[$N II$]$, $[$S II$]$, H${\alpha}$, H${\beta}$) are usually best observable. Our shock detection scheme shows that [S II] and [N II] emissions arise from the thin shell surrounding the SNR, while [O III], H$\rm \alpha$, and H$\rm \beta$ originate from the volume-filling hot gas inside the SNR bubble. We find that the optical emission lines are affected by the SNR’s complex structure and its projection onto the plane of the sky because the escaping line luminosity can be reduced by 10 — 80\% due to absorption along the line-of-sight. Additionally, the subtraction of contaminating background radiation is required for the correct classification of an SNR on the oxygen or sulphur BPT diagrams. The electron temperature and density obtained from our synthetic observations match well with the simulation but are very sensitive to the assumed metallicity.

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E. Makarenko, S. Walch, S. Clarke, et. al.
Mon, 15 May 23
30/53

Comments: 18 pages, 13 figures, accepted for publication in MNRAS

A QPO in Mkn 421 from Archival RXTE Data [HEAP]

http://arxiv.org/abs/2305.07510


We report a 325(-7, +8) day quasi-periodic oscillation (QPO) in the X-ray emission of the blazar Mkn 421, based on data obtained with the Rossi X-ray Timing Explorer (RXTE). The QPO is seen prominently in the ASM data (at least 15 cycles), due to the fact that it has had near-continuous sampling for more than a decade. The PCA data, where the sampling is not uniform and shows many large gaps, provide supporting evidence at lower significance. This QPO is present in both the Proportional Counter Array (PCA) and All-Sky Monitor (ASM) light curves, however it is far more secure (32 sigma significance) in the ASM data since much of the PCA data are from target-of-opportunity flare observations and thus have substantial gaps. QPOs are an important observable in accretion disks, can be modulated by various orbital timescales, and may be generated by a number of mechanisms. They have been studied extensively in X-ray binaries, and should be present in active galactic nuclei (AGN) if they are governed by a common set of physical principles. In jetted sources, QPOs can probe jet-disk interactions or helical oscillations. This QPO previously has been claimed intermittently in X-ray, radio and gamma-ray data, but the continuous, 15-year extent (1996-2011) of the ASM observations (in which Mkn 421 is the brightest AGN observed) provides a unique window. The QPO appears present for nearly the entire extent of the ASM observations. We explore various physical origins and modulating mechanisms, particularly interpretations of the QPO as a result of disk-jet interactions, either due to an accretion disk limit cycle, jet instabilities or helical motions. Limit-cycle related oscillations would not interact with either Keplerian or Lense-Thirring modulated oscillations, however those associated with jet instabilities or helical motions in the jet would likely be modulated by Lense-Thirring precession.

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E. Smith, L. Oramas and E. Perlman
Mon, 15 May 23
33/53

Comments: 10 pages, 8 figures, ApJ, in press

Linking UV spectral properties of MUSE Ly-alpha emitters at z>3 to Lyman continuum escape [GA]

http://arxiv.org/abs/2305.07044


The physical conditions giving rise to high escape fractions of ionising radiation (LyC $f_{\rm{esc}}$) in star-forming galaxies – most likely protagonists of cosmic reionisation – are not yet fully understood. Using the properties of the Lyman-$\alpha$ line profile associated with LyC escape, we select potential LyC leakers and non-leakers from a compiled sample of 1422 MUSE-Wide and MUSE HUDF Lyman-$\alpha$ emitters (LAEs) in the redshift range 2.9<z<6.7. We perform spectral stacking to obtain high signal-to-noise detections of rest-frame UV absorption and emission lines, and find that the stacks with LyC-leaker candidates show (i) strong nebular OIII]1666, [SiIII]1883 and [CIII]1907+CIII]1909 emission, suggesting high ionisation parameters due to an elevated production rate of ionising photons coming from young, metal-poor stars; (ii) high equivalent widths of HeII1640 (~1-3 A), possibly indicating a hard ionising spectrum alongside with a high ionising photon production efficiency; (iii) SiII*1533 emission, revealing the presence of neutral hydrogen off the line of sight, thus implying a highly anisotropic interstellar medium (ISM); (iv) high CIV1548,1550 to [CIII]1907+CIII]1909 ratios (CIV/CIII] > 0.75), partly associated with the increased ISM transparency. In contrast, the stacks with non-leakers show weaker nebular emission lines, low HeII1640 equivalent widths (<1 A), and low CIV/CIII] (<0.25), suggesting a low ionisation state of the ISM and a high neutral hydrogen content. Consequently, our results substantiate that the CIV/CIII] ratio can be used as an indirect tracer of $f_{\rm{esc}}$, providing a promising tool for identification of ionising sources among star-forming galaxies in the epoch of reionisation.

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I. Kramarenko, J. Kerutt, A. Verhamme, et. al.
Mon, 15 May 23
40/53

Comments: 19 pages, 11 figures, submitted to MNRAS

The Spatially Resolved Properties of the GW170817 Host Galaxy [HEAP]

http://arxiv.org/abs/2305.07281


GW170817 is the unique gravitational-wave (GW) event that is associated to the electromagnetic (EM) counterpart GRB 170817A. NGC 4993 is identified as the host galaxy of GW170817/GRB 170817A. In this paper, we particularly focus on the spatially resolved properties of NGC 4993. We present the photometric results from the comprehensive data analysis of the high spatial-resolution images in the different optical bands. The morphological analysis reveals that NGC 4993 is a typical early-type galaxy without significant remnants of major galaxy merger. The spatially resolved stellar population properties of NGC 4993 suggest that the galaxy center has passive evolution with the outskirt formed by gas accretion. We derive the merging rate of the compact object per galaxy by a co-evolution scenario of supermassive black hole and its host galaxy. If the galaxy formation is at redshift 1.0, the merging rate per galaxy is $3.2\times 10^{-4}$ to $7.7\times 10^{-5}$ within the merging decay time from 1.0 to 5.0 Gyr. The results provide the vital information for the ongoing GW EM counterpart detections. The HST data analysis presented in this paper can be also applied for the Chinese Space Station Telescope (CSST) research in the future.

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Y. Li, J. Mao, J. Qin, et. al.
Mon, 15 May 23
45/53

Comments: RAA accepted

Stellar Characterization and Radius Inflation of Hyades M Dwarf Stars From the APOGEE Survey [SSA]

http://arxiv.org/abs/2305.07065


We present a spectroscopic analysis of a sample of 48 M dwarf stars ($0.2 M_{\odot}< M < 0.6 M_{\odot}$) from the Hyades open cluster using high-resolution H-band spectra from the SDSS/APOGEE survey. Our methodology adopts spectrum synthesis with LTE MARCS model atmospheres, along with the APOGEE DR17 line list, to determine effective temperatures, surface gravities, metallicities, and projected rotational velocities. The median metallicity obtained for the Hyades M dwarfs is [M/H]= 0.09$\pm$0.03 dex, indicating a small internal uncertainty and good agreement with optical results for Hyades red-giants. Overall, the median radii are larger than predicted by stellar models by 1.6$\pm$2.3\% and 2.4$\pm$2.3\%, relative to a MIST and DARTMOUTH isochrone, respectively. We emphasize, however, that these isochrones are different and the fractional radius inflation for the fully- and partially-convective regimes have distinct behaviors depending on the isochrone. Using a MIST isochrone there is no evidence of radius inflation for the fully convective stars, while for the partially convective M-dwarfs the radii are inflated by 2.7$\pm$2.1\%, which is in agreement with predictions from models that include magnetic fields. For the partially-convective stars, rapid-rotators present on average higher inflation levels than slow-rotators. The comparison with SPOTS isochrone models indicates that the derived M dwarf radii can be explained by accounting for stellar spots in the photosphere of the stars, with 76\% of the studied M dwarfs having up to 20\% spot coverage, and the most inflated stars with $\sim$20 — 40\% spot coverage.

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F. Wanderley, K. Cunha, D. Souto, et. al.
Mon, 15 May 23
47/53

Comments: Accepted for publication by The Astrophysical Journal (ApJ)

Mini-Quenching of High-Redshift Galaxies by Bursty Star Formation [GA]

http://arxiv.org/abs/2305.07066


The recent observation of a low-mass $z=5.2$ and an intermediate-mass $z=7.3$ (JADES-GS-z7-01-QU) quenched galaxy with JWST / NIRSpec is the first evidence of halted star formation above $z\sim 5$. Here we show how bursty star formation at high redshift gives rise to temporarily quenched, or miniquenched galaxies in the mass range $M_{\star} = 10^7-10^9 \ M_{\odot}$ using three models of galaxy formation: the periodic box simulation IllustrisTNG, the zoom-in simulation VELA and an empirical halo model. The main causes for mini-quenching are stellar feedback, lack of gas accretion onto galaxies and galaxy-galaxy interactions. The abundance of mini-quenching events agrees across the three models: the population first appears below $z\sim 8$, after which the fraction of miniquenched galaxies increases with cosmic time, from $\sim 0.5$% at $z=7$ to $\sim 1-2$% at $z=4$, corresponding to comoving number densities of $8.0\times 10^{-6}$ Mpc$^{-3}$ and $5.4\times 10^{-4}$ Mpc$^{-3}$, respectively. The star formation rate duty cycle ($f_{\mathrm{duty}}\sim 99.56^{+0.4}_{-4.5}$% at $z=7$) inferred for VELA galaxies is consistent therewith. Star formation histories (SFHs) in VELA suggest that mini-quenching at $z=4-8$ is short-lived with a duration of $\sim 20-40$ Myr, which is close to the free-fall timescale of the inner halo. However, mock spectral energy distributions of miniquenched galaxies in IllustrisTNG and VELA do not match JADES-GS-z7-01-QU photometry, unless their SFHs are artificially altered to be more bursty on timescales of $\sim 40$ Myr. Studying miniquenched galaxies might aid in calibrating the sub-grid models governing galaxy formation, as these may not generate sufficient burstiness at high redshift to explain the SFH inferred for JADES-GS-z7-01-QU.

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T. Dome, S. Tacchella, A. Fialkov, et. al.
Mon, 15 May 23
49/53

Comments: Submitted to MNRAS, 10 pages, 3 figures, 2 tables, comments welcome

The outer low-$α$ disc of the Milky Way — I: evidence for the first pericentric passage of Sagittarius? [GA]

http://arxiv.org/abs/2305.07426


Phase-space data, chemistry, and ages together reveal a complex structure in the outer low-${\alpha}$ disc of the Milky Way. The age-vertical velocity dispersion profiles beyond the Solar Neighbourhood show a significant jump at 6 Gyr for stars beyond the Galactic plane. Stars older than 6 Gyr are significantly hotter than younger stars. The chemistry and age histograms reveal a bump at [Fe/H] = -0.5, [${\alpha}$/Fe] = 0.1, and an age of 7.2 Gyr in the outer disc. Finally, viewing the stars beyond 13.5 kpc in the age-metallicity plane reveals a faint streak just below this bump, towards lower metallicities at the same age. Given the uncertainty in age, we believe these features are linked and suggest a pericentric passage of a massive satellite 6 Gyr ago that heated pre-existing stars, led to a starburst in existing gas. New stars also formed from the metal-poorer infalling gas. The impulse approximation was used to characterise the interaction with a satellite, finding a mass of ~1e11 M$_{\odot}$, and a pericentric position between 12 and 16 kpc. The evidence points to an interaction with the Sagittarius dwarf galaxy, likely its first pericentric passage.

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P. Das, Y. Huang, I. Ciuca, et. al.
Mon, 15 May 23
51/53

Comments: 10 pages, 6 figures, submitted to MNRAS

FAST drift scan survey for HI intensity mapping: I. preliminary data analysis [CEA]

http://arxiv.org/abs/2305.06405


This work presents the initial results of the drift-scan observation for the neutral hydrogen (HI) intensity mapping survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The data analyzed in this work were collected in night observations from 2019 through 2021. The primary findings are based on 28 hours of drift-scan observation carried out over seven nights in 2021, which covers $60\,{\rm deg}^2$ sky area. Our main findings are: (i) Our calibration strategy can successfully correct both the temporal and bandpass gain variation over the $4$-hour drift-scan observation. (ii) The continuum maps of the surveyed region are made with frequency resolution of $28$ kHz and pixel area of $2.95\,{\rm arcmin}^2$. The pixel noise levels of the continuum maps are slightly higher than the forecast assuming $T_{\rm sys}=20\,{\rm K}$, which are $36.0$ mK (for 10.0 s integration time) at the $1050$–$1150$ MHz band, and $25.9$ mK (for 16.7 s integration time) at the $1323$–$1450$ MHz band, respectively. (iii) The flux-weighted differential number count is consistent with the NRAO-VLA Sky Survey (NVSS) catalog down to the confusion limit $\sim7\,{\rm mJy}/{\rm beam}^{-1}$. (iv) The continuum flux measurements of the sources are consistent with that found in the literature. The difference in the flux measurement of $81$ isolated NVSS sources is about $6.3\%$. Our research offers a systematic analysis for the FAST HI intensity mapping drift-scan survey and serves as a helpful resource for further cosmology and associated galaxies sciences with the FAST drift-scan survey.

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Y. Li, Y. Wang, F. Deng, et. al.
Fri, 12 May 23
9/53

Comments: 26 pages, 26 figures, and 4 tables

Dust Properties of 870 Micron Selected Galaxies in the GOODS-S [GA]

http://arxiv.org/abs/2305.06388


We analyze the dust properties of 57 870 $\mu$m selected dusty star-forming galaxies in the GOODS-S using new deep ALMA 1.2 mm, 2 mm, and 3 mm continuum imaging together with other far-infrared through millimeter data. We fit the spectral energy distributions (SEDs) with optically thin modified blackbodies to constrain the emissivity indices and effective dust temperatures, finding a median emissivity index of $\beta = 1.78^{+0.43}{-0.25}$ and a median temperature of $T_d = 33.6^{+12.1}{-5.4}$ K. We observe a negative correlation between $\beta$ and $T_d$. By testing several SED models, we determine that the derived emissivity indices can be influenced by opacity assumptions. Our temperature measurements are consistent with no evolution in dust temperature with redshift.

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S. McKay, A. Barger, L. Cowie, et. al.
Fri, 12 May 23
10/53

Comments: Accepted for publication in ApJ. 21 pages, 12 figures, 2 tables

The Next Generation Virgo Cluster Survey (NGVS). XXXV. First Kinematical Clues of Overly-Massive Dark Matter Halos in Several Ultra-Diffuse Galaxies in the Virgo Cluster [GA]

http://arxiv.org/abs/2305.06369


We present Keck/DEIMOS spectroscopy of the first complete sample of ultra-diffuse galaxies (UDGs) in the Virgo cluster. We select all UDGs in Virgo that contain at least 10 globular cluster (GC) candidates and are more than $2.5\sigma$ outliers in scaling relations of size, surface brightness, and luminosity (a total of 10 UDGs). We use the radial velocity of their GC satellites to measure the velocity dispersion of each UDG. We find a mixed bag of galaxies: from one UDG that shows no signs of dark matter, to UDGs that follow the luminosity-dispersion relation of early-type galaxies, to the most extreme examples of heavily dark matter dominated galaxies that break well-known scaling relations such as the luminosity-dispersion or the U-shaped total mass-to-light ratio relations. This is indicative of a number of mechanisms at play forming these peculiar galaxies. Some of them may be the most extended version of dwarf galaxies, while others are so extreme that they seem to populate dark matter halos consistent with that of the Milky-Way or even larger. Even though Milky-Way stars and other GC interlopers contaminating our sample of GCs cannot be fully ruled-out, our assessment of this potential problem and simulations indicate that the probability is low and, if present, unlikely to be enough to explain the extreme dispersions measured. Further confirmation from stellar kinematics studies in these UDGs would be desirable. The lack of such extreme objects in any of the state-of-the-art simulations, opens an exciting avenue of new physics shaping these galaxies.

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E. Toloba, L. Sales, S. Lim, et. al.
Fri, 12 May 23
12/53

Comments: 27 pages, 12 figures. Accepted for publication in ApJ

Merger Conditions of Population III Protostar Binaries [SSA]

http://arxiv.org/abs/2305.06843


Massive close binary stars with extremely small separations have been observed, and they are possible progenitors of gravitational-wave sources. The evolution of massive binaries in the protostellar accretion stage is key to understanding their formation process. We, therefore, investigate how close the protostars, consisting of a high-density core and a vast low-density envelope, can approach each other but not coalesce. To investigate the coalescence conditions, we conduct smoothed particle hydrodynamics simulations following the evolution of equal-mass binaries with different initial separations. Since Population (Pop) I and III protostars have similar interior structures, we adopt a specific Pop~III model with the mass and radius of $7.75\;M_{\odot}$ and $61.1\;R_{\odot}$ obtained by the stellar evolution calculations. Our results show that the binary separation decreases due to the transport of the orbital angular momentum to spin angular momentum. If the initial separation is less than about 80 per~cent of the sum of the protostellar radius, the binary coalesces in a time shorter than the tidal lock timescale. The mass loss up to the merging is $\lesssim 3$ per~cent. After coalescence, the star rotates rapidly, and its interior structure is independent of the initial separation. We conclude that there must be some orbital shrinking mechanism after the protostars contract to enter the zero-age main-sequence stage.

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T. Kirihara, H. Susa, T. Hosokawa, et. al.
Fri, 12 May 23
19/53

Comments: 17 pages, 13 figures, Accepted for Publication in ApJ

Detection of multiple phase space overdensities of GSE stars by orbit integration [GA]

http://arxiv.org/abs/2305.06759


In N-body simulations, nearly radial mergers can form shell-like overdensities in the sky position and phase space ($r-v_r$) due to the combination of dynamical friction and tidal stripping. The merger event of Gaia-Sausage-Enceladus has provided a unique opportunity to study the shells in the phase space. To search for them, we integrate the orbits of 5949 GSE-related halo K giants from the LAMOST survey and record their positions at all time intervals in $r-v_r$ diagram. After the subtraction of a smoothed background, we find six significant and complete thin chevron-like overdensities. The apocenters $r_\mathrm{apo}$ of stars in the six chevrons are around 6.75, 12.75, 18.75, 25.25, 27.25, and 30.25 kpc. These chevrons reveal the multiple pile-ups of GSE stars at different apocenters. The application of a different Milky Way mass $M_\mathrm{vir}$ will change the opening angles of these chevrons, while leave their apocenters almost unchanged. By comparing with a recent study of the phase space overdensities of local halo stars from Gaia RVS survey, our results are more inclined to a medium $M_\mathrm{vir}$ of $10^{12}\,M_\odot$. The application of a non-axisymmetric Galactic potential with a steadily rotating bar has a blurring effect on the appearance of these chevron-like overdensities, especially for the chevrons with $r_\mathrm{apo} > 20$ kpc.

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W. WenboWu, G. GangZhao, J. JiangChang, et. al.
Fri, 12 May 23
20/53

Comments: Accepted by ApJ, 8 figures

QUIJOTE scientific results — X. Spatial variations of Anomalous Microwave Emission along the Galactic plane [GA]

http://arxiv.org/abs/2305.06762


Anomalous Microwave Emission (AME) is an important emission component between 10 and 60 GHz that is not yet fully understood. It seems to be ubiquituous in our Galaxy and is observed at a broad range of angular scales. Here we use the new QUIJOTE-MFI wide survey data at 11, 13, 17 and 19 GHz to constrain the AME in the Galactic plane ($|b|<10^\circ$) on degree scales. We built the spectral energy distribution between 0.408 and 3000 GHz for each of the 5309 0.9$^\circ$, pixels in the Galactic plane, and fitted a parametric model by considering five emission components: synchrotron, free-free, AME, thermal dust and CMB anisotropies. We show that not including QUIJOTE-MFI data points leads to the underestimation (up to 50 %) of the AME signal in favour of free-free emission. The parameters describing these components are then intercompared, looking for relations that help to understand AME physical processes. We find median values for the AME width, $W_{\rm AME}$, and for its peak frequency, $\nu_{\rm AME}$, respectively of $0.560^{+0.059}{-0.050}$ and $20.7^{+2.0}{-1.9}$ GHz, slightly in tension with current theoretical models. We find spatial variations throughout the Galactic plane for $\nu_{\rm AME}$, but only with reduced statistical significance. We report correlations of AME parameters with certain ISM properties, such as that between the AME emissivity (which shows variations with the Galactic longitude) and the interstellar radiation field, and that between the AME peak frequency and dust temperature. Finally, we discuss the implications of our results on the possible molecules responsible for AME.

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M. Fernández-Torreiro, J. Rubiño-Martín, C. López-Caraballo, et. al.
Fri, 12 May 23
24/53

Comments: 32 pages, 31 figures. Submitted to MNRAS. Derived data products available at this https URL

How to Flip a Bar [GA]

http://arxiv.org/abs/2305.06383


Galactic bars, made up of elongated and aligned stellar orbits, can lose angular momentum via resonant torques with dark matter particles in the halo and slow down. Here we show that if a stellar bar is decelerated to zero rotation speed, it can flip the sign of its angular momentum and reverse rotation direction. We demonstrate this in a collisionless N-body simulation of a galaxy in a live counter-rotating halo. Reversal begins at small radii and propagates outward. The flip generates a kinematically-decoupled core both in the visible galaxy and in the dark matter halo, and counter-rotation generates a large-scale warp of the outer disk with respect to the bar.

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A. Collier and A. Madigan
Fri, 12 May 23
28/53

Comments: 9 pages, 8 figures, MNRAS in review

Constraining Primordial Magnetic Fields with Line-Intensity Mapping [CEA]

http://arxiv.org/abs/2305.06440


Primordial magnetic fields (PMFs) offer a compelling explanation for the origin of observed magnetic fields, especially on extragalactic scales. Such PMFs give rise to excess of power in small scale matter perturbations that could strongly influence structure formation. We study the impact of the magnetically enhanced matter power spectrum on the signal that will be observed by line-intensity mapping (LIM) surveys targeting carbon monoxide (CO) emission from star-forming galaxies at high redshifts. Specifically, the voxel intensity distribution of intensity maps provides access to small-scale information, which makes it highly sensitive to signatures of PMFs on matter overdensities. We present forecasts for future LIM CO surveys, finding that they can constrain PMF amplitudes as small as $\sigma_{B,0}\sim0.04-1\,{\rm nG}$, depending on the magnetic spectral index and the targeted redshifts.

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T. Adi, S. Libanore, H. Cruz, et. al.
Fri, 12 May 23
29/53

Comments: 9 pages, 3 figures, 2 tables

Time evolution of Ce as traced by APOGEE using giant stars observed with the Kepler, TESS and K2 missions [GA]

http://arxiv.org/abs/2305.06396


Abundances of s-capture process elements in stars with exquisite asteroseismic, spectroscopic, and astrometric constraints offer a novel opportunity to study stellar evolution, nucleosynthesis, and Galactic chemical evolution. We aim to investigate one of the least studied s-process elements in the literature, Ce, using stars with asteroseismic constraints from the Kepler, K2 and TESS missions. We combine the global asteroseismic parameters derived from precise light curves obtained by the Kepler, K2 and TESS missions with chemical abundances from the APOGEE DR17 survey and astrometric data from the Gaia mission. Finally, we compute stellar ages using the code PARAM. We investigate the different trends of [Ce/Fe] as a function of [Fe/H], [alpha/Fe] and age considering the dependence on the radial position, specially in the case of K2 targets which cover a large Galactocentric range. We, finally, explore the [Ce/alpha] ratios as a function of age in different Galactocentric intervals. The studied trends display a strong dependence of the Ce abundances on [Fe/H] and star formation history. Indeed, the [Ce/Fe] ratio shows a non-monotonic dependence on [Fe/H] with a peak around -0.2 dex. Moreover, younger stars have higher [Ce/Fe] and [Ce/alpha] ratios than older stars, confirming the latest contribution of low- and intermediate-mass asymptotic giant branch stars to the Galactic chemical enrichment. In addition, the trends of [Ce/Fe] and [Ce/alpha] with age become steeper moving towards the outer regions of the Galactic disc, demonstrating a more intense star formation in the inner regions than in the outer regions. Ce is thus a potentially interesting element to help constraining stellar yields and the inside-out formation of the Milky Way disc. However, the large scatter in all the relations studied here, suggests that spectroscopic uncertainties for this element are still too large.

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G. Casali, V. Grisoni, A. Miglio, et. al.
Fri, 12 May 23
31/53

Comments: Accepted for publication in A&A, 18 pages, 18 figures

Halo mass-observable proxy scaling relations and their dependencies on galaxy and group properties [GA]

http://arxiv.org/abs/2305.06803


Based on the DECaLS shear catalog, we study the scaling relations between halo mass($M_{\rm h}$) and various proxies for SDSS central galaxies, including stellar mass($M_$), stellar velocity dispersion($\sigma_$), abundance matching halo mass($M_{\rm AM}$) and satellite velocity dispersion($\sigma_{\rm s}$), and their dependencies on galaxy and group properties. In general, they are all good proxies of $M_{\rm h}$, and their scaling relations are consistent with previous studies. We find that the $M_{\rm h}$-$M_$ and $M_{\rm h}$-$\sigma_$ relations depend strongly on group richness($N_{\rm sat}$), while the $M_{\rm h}$-$M_{\rm AM}$ and $M_{\rm h}$-$\sigma_{\rm s}$ relations are independent of it. Moreover, the dependence on star formation rate(SFR) is rather weak in the $M_{\rm h}$-$\sigma_$ and $M_{\rm h}$-$\sigma_{\rm s}$ relations, but very prominent in the other two. $\sigma_{\rm s}$ is thus the best proxy among them, and its scaling relation is in good agreement with hydro-dynamical simulations. However, estimating $\sigma_{\rm s}$ accurately for individual groups/clusters is challenging because of interlopers and the requirement for sufficient satellites. We construct new proxies by combining $M_$, $\sigma_$, and $M_{\rm AM}$, and find the proxy with 30\% contribution from $M_{\rm AM}$ and 70\% from $\sigma_$ can minimize the dependence on $N_{\rm sat}$ and SFR. We obtain the $M_{\rm h}$-supermassive black hole(SMBH) mass relation via the SMBH scaling relation and find indications for rapid and linear growth phases for SMBH. We also find that correlations among $M_{\rm h}$, $M_$ and $\sigma_$ change with $M_*$, indicating that different processes drive the growth of galaxies and SMBH at different stages.

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Z. Zhang, H. Wang, W. Luo, et. al.
Fri, 12 May 23
37/53

Comments: 24 pages, 12 figures and 3 tables

Intracluster light in the core of z~2 galaxy proto-clusters [GA]

http://arxiv.org/abs/2305.06385


Intracluster light is thought to originate from stars that were ripped away from their parent galaxies by gravitational tides and galaxy interactions during the build up of the cluster. The stars from such interactions will accumulate over time, so semi-analytic models suggest that the abundance of intracluster stars is negligible in young proto-clusters at z~2 and grows to around a quarter of the stellar mass in the oldest, most mature clusters. In contrast to these theoretical expectations, we report on the detection of intracluster light within two proto-clusters at z=2 using deep HST images. We use the colour of the intracluster light to estimate its mass-to-light ratio in annuli around the brightest cluster galaxies (BCG), up to a radius of 100 kpc. We find that $54\pm5$\% and $71\pm3$\% of the stellar mass in these regions is located more than 10 kpc away from the BCGs in the two proto-clusters. This low concentration is similar to BCGs in lower redshift clusters, and distinct from other massive proto-cluster galaxies. This suggests that intracluster stars are already present within the core 100 kpc of proto-clusters. We compare these observations to the Hydrangea hydrodynamical galaxy cluster simulations and find that intracluster stars are predicted to be a generic feature of group-sized halos at z=2. These intracluster stars will gradually move further away from the BCG as the proto-cluster assembles into a cluster.

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S. Werner, N. Hatch, J. Matharu, et. al.
Fri, 12 May 23
39/53

Comments: 14 pages, 9 figures, paper accepted for publication by MNRAS

Testing the linear relationship between black hole mass and variability timescale in low-luminosity AGN at submillimeter wavelengths [HEAP]

http://arxiv.org/abs/2305.06529


The variability of submillimeter emission provides a useful tool to probe the accretion physics in low-luminosity active galactic nuclei. We accumulate four years of observations using Submillimeter Array for Centaurus A, NGC 4374, NGC 4278, and NGC 5077 and one year of observations for NGC 4552 and NGC 4579. All sources are variable. We measure the characteristic timescale at which the variability is saturated by modeling these sources’ light curve as a damped random walk. We detect a timescale for all the sources except NGC 4552. The detected timescales are comparable to the orbital timescale at the event horizon scale for most sources. Combined with previous studies, we show a correlation between the the timescale and the black hole mass over three orders of magnitude. This discovery suggests the sub-mm emission is optically thin with the emission originating from the event horizon. The mass scaling relationship further suggests that a group of radio sources with a broadband spectrum that peaks at submillimeter wavelengths have similar inner accretion physics. Sources that follow this relationship may be good targets for high-resolution imaging with the Event Horizon Telescope.

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B. Chen, G. Bower, J. Dexter, et. al.
Fri, 12 May 23
41/53

Comments: 18 pages, 7 figures, 4 tables, accepted for publication by ApJ

X-Shooting ULLYSES: massive stars at low metallicity. I. Project Description [SSA]

http://arxiv.org/abs/2305.06376


Observations of individual massive stars, super-luminous supernovae, gamma-ray bursts, and gravitational-wave events involving spectacular black-hole mergers, indicate that the low-metallicity Universe is fundamentally different from our own Galaxy. Many transient phenomena will remain enigmatic until we achieve a firm understanding of the physics and evolution of massive stars at low metallicity (Z).
The Hubble Space Telescope has devoted 500 orbits to observe 250 massive stars at low Z in the ultraviolet (UV) with the COS and STIS spectrographs under the ULLYSES program.
The complementary “X-Shooting ULLYSES” (XShootU) project provides enhanced legacy value with high-quality optical and near-infrared spectra obtained with the wide-wavelength coverage X-shooter spectrograph at ESO’s Very Large Telescope.
We present an overview of the XShootU project, showing that combining ULLYSES UV and XShootU optical spectra is critical for the uniform determination of stellar parameters such as effective temperature, surface gravity, luminosity, and abundances, as well as wind properties such as mass-loss rates in function of Z. As uncertainties in stellar and wind parameters percolate into many adjacent areas of Astrophysics, the data and modelling of the XShootU project is expected to be a game-changer for our physical understanding of massive stars at low Z.
To be able to confidently interpret James Webb Space Telescope (JWST) spectra of the first stellar generations, the individual spectra of low Z stars need to be understood, which is exactly where XShootU can deliver.

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V. S., M. A., C. P.A., et. al.
Fri, 12 May 23
42/53

Comments: Accepted in A&A – 35 Pages, 12 Figures, 4 Tables, 2 Large Tables

A radio-jet driven outflow in the Seyfert 2 galaxy NGC 2110? [GA]

http://arxiv.org/abs/2305.06366


We present a spatially-resolved study of the ionised gas in the central 2 kpc of the Seyfert 2 galaxy NGC 2110 and investigate the role of its moderate luminosity radio jet (kinetic radio power of $P_\mathrm{jet} = 2.3 \times 10^{43}\mathrm{erg\ s^{-1}}$). We use new optical integral-field observations taken with the MEGARA spectrograph at GTC. We fit the emission lines with a maximum of two Gaussian components, except at the AGN position where we used three. Aided by existing stellar kinematics, we use the observed velocity and velocity dispersion of the emission lines to classify the different kinematic components. The disc component is characterised by lines with $\sigma \sim 60-200\ \mathrm{km\ s^{-1}}$. The outflow component has typical values of $\sigma \sim 700\ \mathrm{km\ s^{-1}}$ and is confined to the central 400 pc, which is coincident with linear part of the radio jet detected in NGC 2110. At the AGN position, the [O III]$\lambda$5007 line shows high velocity components reaching at least $1000\ \mathrm{km\ s^{-1}}$. This and the high velocity dispersions indicate the presence of outflowing gas outside the galaxy plane. Spatially-resolved diagnostic diagrams reveal mostly LI(N)ER-like excitation in the outflow and some regions in the disc, which could be due to the presence of shocks. However, there is also Seyfert-like excitation beyond the bending of the radio jet, probably tracing the edge of the ionisation cone that intercepts with the disc of the galaxy. NGC 2110 follows well the observational trends between the outflow properties and the jet radio power found for a few nearby Seyfert galaxies. All these pieces of information suggest that part of observed ionised outflow in NGC 2110 might be driven by the radio jet. However, the radio jet was bent at radial distances of 200 pc (in projection) from the AGN, and beyond there, most of the gas in the galaxy disc is rotating.

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L. Arriba, A. Alonso-Herrero, S. García-Burillo, et. al.
Fri, 12 May 23
44/53

Comments: 25 pages, 22 figures, 3 tables. Accepted for publication in A&A

Exploring connections between the VLBI and optical morphology of AGNs and their host galaxies [GA]

http://arxiv.org/abs/2305.06713


We analyse VLBI and optical images of AGNs and their host galaxies and look for statistical correlations between the shape and orientation of the galaxy and the direction of the jet. We utilise the Astrogeo catalogue, which has over 9000 VLBI sources, many of those with a clear core-jet like structure that allows for the jet position angle to be reliably determined. We then use the VLBI source positions to search for optical counterparts within various optical surveys. In order to parameterise the orientation and shape of the host galaxy, we fitted a Gaussian elliptical model to the optical image, taking the PSF into account. We check our own shape parameters from this fit against the ones provided by the optical surveys. As of yet, no clear correlation between the galaxy morphology and the jet direction is seen.

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D. Gil, J. Hodgson and B. L’Huillier
Fri, 12 May 23
47/53

Comments: IAU Symposium No. 375 Proceedings, 4 pages, 4 figures, 1 table

A Wide View of the Galactic Globular Cluster NGC 2808: Red Giant and Horizontal Branch Star Spatial Distributions [GA]

http://arxiv.org/abs/2305.06419


Wide-field and deep DECam multi-band photometry, combined with HST data for the core of the Galactic globular cluster NGC 2808, allowed us to study the distribution of various stellar sub-populations and stars in different evolutionary phases out to the cluster tidal radius. We used the C_ugi = (u-g)-(g-i) index to identify three chemically distinct sub-populations along the red giant branch and compared their spatial distributions. The most light-element enriched sub-population (P3) is more centrally concentrated; however, it shows a more extended distribution in the external regions of the cluster compared to the primordial (P1) and intermediate (P2) composition populations. Furthermore, the P3 sub-population centroid is off-center relative to those of the P1 and P2 groups. We also analyzed the spatial distribution of horizontal branch stars and found that the relative fraction of red horizontal branch stars increases for radial distances larger than ~ 1.5′ while that of the blue and hotter stars decreases. These new observations, combined with literature spectroscopic measurements, suggest that the red horizontal branch stars are the progeny of all the stellar sub-populations in NGC 2808, i.e. primordial and light-element enhanced, while the blue stars are possibly the result of a combination of the “hot-flasher” and the “helium-enhanced” scenarios. A similar distribution of different red giant branch sub-populations and horizontal branch stars was also found for the most massive Galactic globular cluster, omega Cen, based on combined DECam and HST data, which suggests the two may share a similar origin.

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C. Johnson, A. Calamida, J. Kader, et. al.
Fri, 12 May 23
49/53

Comments: Accepted for publication in AJ; 22 pages; 16 figures; the full version of table 2 will be available in electronic form with the published version

Evidence of Space weather in Radon Decay [CL]

http://arxiv.org/abs/2305.06882


The Electron, Proton and Alpha Monitor, EPAM, located at the L1 Position approximately 1-million miles from the earth in the direction of the sun, was designed to detect fluctuations in solar output through counting the numbers of various particles hitting the detector. The EPAM detector is part of an early warning system that can alert the earth to coronal mass ejection events that can damage our electronic grids and satellite equipment. EPAM gives a real-time estimate of changes in the local solar magnetic field directed towards the earth, recorded in the fluctuations of solar particles being ejected. This paper presents an analysis of fluctuations in data taken by the Geological Survey of Israel, GSI, compared to the changes in detected numbers of protons as seen by EPAM. Surprisingly, the GSI and EPAM detectors show an unexpected correlation between the variation in count rate detected by the GSI detectors and an increased numbers of protons seen at EPAM; well above statistical significance of 5-sigma, indicating a non-random connection between the data sets. The statistically significant overlap between data taken by these two detectors, subject to very different conditions, may hint at a Primakoff mechanism whereby exotic particles, e.g. galactic Dark Matter, couple through magnetic fields to both photons and even nuclei. This work builds on an earlier paper on the observations of Radon decay and their implications for particle physics.

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C. Scarlett, E. Fischbach, B. Freeman, et. al.
Fri, 12 May 23
51/53

Comments: N/A

Revisiting the Properties of X-ray AGN in the SSA22 Protocluster: Normal SMBH and Host-Galaxy Growth for AGN in a $z=3.09$ Overdensity [GA]

http://arxiv.org/abs/2305.06400


We analyze the physical properties of 8 X-ray selected active galactic nuclei (AGN) and one candidate protoquasar system (ADF22A1) in the $z = 3.09$ SSA22 protocluster by fitting their X-ray-to-IR spectral energy distributions (SEDs) using our SED fitting code, Lightning. We recover star formation histories (SFH) for 7 of these systems which are well-fit by composite stellar population plus AGN models. We find indications that 4/9 of the SSA22 AGN systems we study have host galaxies below the main sequence, with $\rm SFR/SFR_{MS} \leq -0.4$. The remaining SSA22 systems, including ADF22A1, are consistent with obscured supermassive black hole (SMBH) growth in star forming galaxies. We estimate the SMBH accretion rates and masses, and compare the properties and SFH of the 9 protocluster AGN systems with X-ray detected AGN candidates in the Chandra Deep Fields (CDF), finding that the distributions of SMBH growth rates, star formation rates, SMBH masses, and stellar masses for the protocluster AGN are consistent with field AGN. We constrain the ratio between the sample-averaged SSA22 SMBH mass and CDF SMBH mass to $<1.41$. While the AGN are located near the density peaks of the protocluster, we find no statistically significant trends between the AGN or host galaxy properties and their location in the protocluster. We interpret the similarity of the protocluster and field AGN populations together with existing results as suggesting that the protocluster and field AGN co-evolve with their hosts in the same ways, while AGN-triggering events are more likely in the protocluster.

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E. Monson, K. Doore, R. Eufrasio, et. al.
Fri, 12 May 23
52/53

Comments: 27 pages, 14 figures, 8 tables. Accepted in ApJ

ALMA 1.1mm Observations of a Conservative Sample of High Redshift Massive Quiescent Galaxies in SHELA [GA]

http://arxiv.org/abs/2305.06309


We present a sample of 30 massive (log$(M_{\ast}/M_\odot) >11$) $z=3-5$ quiescent galaxies selected from the \textit{Spitzer-}HETDEX Exploratory Large Area (SHELA) Survey and observed at 1.1mm with Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 observations. These ALMA observations would detect even modest levels of dust-obscured star-formation, on order of $\sim 20 \ M_\odot \textrm{yr}^{-1}$ at $z\sim4$ at a $1\sigma$ level, allowing us to quantify the amount of contamination from dusty star-forming sources in our quiescent sample. Starting with a parent sample of candidate massive quiescent galaxies from the Stevans et al. 2021 v1 SHELA catalog, we use the Bayesian \textsc{Bagpipes} spectral energy distribution fitting code to derive robust stellar masses ($M_$) and star-formation rates (SFRs) for these sources, and select a conservative sample of 36 candidate massive ($M_ > 10^{11}M_\odot$) quiescent galaxies, with specific SFRs at $>2\sigma$ below the star-forming main sequence at $z\sim4$. Based on ALMA imaging, six of these candidate quiescent galaxies have the presence of significant dust-obscured star-formation, thus were removed from our final sample. This implies a $\sim 17\%$ contamination rate from dusty star-forming galaxies with our selection criteria using the v1 SHELA catalog. This conservatively-selected quiescent galaxy sample at $z=3-5$ will provide excellent targets for future observations to better constrain how massive galaxies can both grow and shut-down their star-formation in a relatively short time period.

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K. Chworowsky, S. Finkelstein, J. Spilker, et. al.
Thu, 11 May 23
1/55

Comments: 16 pages, 13 figures

Spectrum of the linearized Vlasov–Poisson equation around steady states from galactic dynamics [CL]

http://arxiv.org/abs/2305.05749


We study the linearized Vlasov-Poisson equation in the gravitational case around steady states that are decreasing and continuous functions of the energy. We identify the absolutely continuous spectrum and give criteria for the existence of oscillating modes and estimate their number. Our method allows us to take into account an attractive external potential.

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M. Moreno, P. Rioseco and H. Bosch
Thu, 11 May 23
5/55

Comments: 17 pages, 2 figures

The impact of UV variability on the abundance of bright galaxies at $z \geq 9$ [GA]

http://arxiv.org/abs/2305.05679


JWST observations have revealed a population of galaxies bright enough that potentially challenge standard galaxy formation models in the $\Lambda$CDM cosmology. Using a minimal empirical framework, we investigate the influence of variability on the rest-frame ultra-violet (UV) luminosity function (UVLF) of galaxies at $z\geq 9$. Our study differentiates between the $\textit{median UV radiation yield}$ and the $\textit{variability of UV luminosities}$ of galaxies at a fixed dark matter halo mass. We primarily focus on the latter effect, which depends on halo assembly and galaxy formation processes and can significantly increase the abundance of UV-bright galaxies due to the upscatter of galaxies in lower-mass haloes. We find that a relatively low level of variability, $\sigma_{\rm UV} \approx 0.75$ mag, matches the observational constraints at $z\approx 9$. However, increasingly larger $\sigma_{\rm UV}$ is necessary when moving to higher redshifts, reaching $\sigma_{\rm UV} \approx 2.0\,(2.5)\,{\rm mag}$ at $z\approx 12$ ($16$). This implied variability is consistent with expectations of physical processes in high-redshift galaxies such as bursty star formation and cycles of dust clearance. Photometric constraints from JWST at $z\gtrsim 9$ therefore can be reconciled with a standard $\Lambda$CDM-based galaxy formation model calibrated at lower redshifts without the need for adjustments to the median UV radiation yield.

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X. Shen, M. Vogelsberger, M. Boylan-Kolchin, et. al.
Thu, 11 May 23
6/55

Comments: 6 pages, 3 figures. To be submitted. Comments are welcome

Stellar Parameters and Chemical Abundances Estimated from LAMOST-II DR8 MRS based on Cycle-StarNet [SSA]

http://arxiv.org/abs/2305.05854


Deriving stellar atmospheric parameters and chemical abundances from stellar spectra is crucial for understanding the evolution of the Milky Way. By performing a fitting with MARCS model atmospheric theoretical synthetic spectra combined with a domain-adaptation method, we estimate the fundamental stellar parameters (Teff, log g, [Fe/H], vmic, and vmac) and 11 chemical abundances for 1.38 million FGKM-type stars of the Medium-Resolution Spectroscopic Survey (MRS) from LAMOST-II DR8. The domain-adaptation method, Cycle-StarNet, is employed to reduce the gap between observed and synthetic spectra, and the L-BFGS algorithm is used to search for the best-fit synthetic spectra. By combining the 2MASS photometric survey data, Gaia EDR3 parallax, and MIST isochrones, the surface gravities of the stars are constrained after estimating their bolometric luminosities. The accuracy of Teff, log g, and [Fe/H] can reach 150 K, 0.11 dex, and 0.15 dex, evaluated by the PASTEL catalog, asteroseismic samples, and other spectroscopic surveys. The precision of these parameters and elemental abundances ([C/Fe], [Na/Fe], [Mg/Fe], [Si/Fe], [Ca/Fe], [Ti/Fe], [Cr/Fe], [Mn/Fe], [Co/Fe], [Ni/Fe], and [Cu/Fe]) is assessed by repeated observations and validated by cluster members. For spectra with signal-to-noise (S/N) ratios greater than 10, the precision of the three stellar parameters and elemental abundances can achieve 76 K, 0.014 dex, 0.096 dex, and 0.04-0.15 dex. For spectra with S/N ratios higher than 100, the precision stabilizes at 22 K, 0.006 dex, 0.043 dex, and 0.01-0.06 dex. The full LAMOST MRS stellar properties catalog is available online.

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R. Wang, A. Luo, S. Zhang, et. al.
Thu, 11 May 23
7/55

Comments: Accepted for publication in ApJS

A 3D physico-chemical model of a pre-stellar core. I. Environmental and structural impact on the distribution of CH$_3$OH and $c$-C$_3$H$_2$ [GA]

http://arxiv.org/abs/2305.05932


Pre-stellar cores represent the earliest stage of the star- and planet-formation process. By characterizing the physical and chemical structure of these cores we can establish the initial conditions for star and planet formation and determine to what degree the chemical composition of pre-stellar cores is inherited to the later stages. A 3D MHD model of a pre-stellar core embedded in a dynamic star-forming cloud is post-processed using sequentially continuum radiative transfer, a gas-grain chemical model, and a line-radiative transfer model. Results are analyzed and compared to observations of CH$_3$OH and $c$-C$_3$H$_2$ in L1544. Nine different chemical models are compared to the observations to determine which initial conditions are compatible with the observed chemical segregation in the prototypical pre-stellar core L1544. The model is able to reproduce several aspects of the observed chemical differentiation in L1544. Extended methanol emission is shifted towards colder and more shielded regions of the core envelope while $c$-C$_3$H$_2$ emission overlaps with the dust continuum, consistent with the observed chemical structure. Increasing the strength of the interstellar radiation field or the cosmic-ray ionization rate with respect to the typical values assumed in nearby star-forming regions leads to synthetic maps that are inconsistent with the observed chemical structure. Our model shows that the observed chemical dichotomy in L1544 can arise as a result of uneven illumination due to the asymmetrical structure of the 3D core and the environment within which the core has formed. This highlights the importance of the 3D structure at the core-cloud transition on the chemistry of pre-stellar cores.

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S. Jensen, S. Spezzano, P. Caselli, et. al.
Thu, 11 May 23
11/55

Comments: Accepted for publication in A&A

NGC 1436: the making of a lenticular galaxy in the Fornax cluster [GA]

http://arxiv.org/abs/2305.05709


We study the evolutionary path of the Fornax cluster galaxy NGC$~$1436, which is known to be currently transitioning from a spiral into a lenticular morphology. This galaxy hosts an inner star-forming disc and an outer quiescent disc, and we analyse data from the MeerKAT Fornax Survey, ALMA, and the Fornax3D survey to study the interstellar medium and the stellar populations of both disc components. Thanks to the combination of high resolution and sensitivity of the MeerKAT data, we find that the $\textrm{H}\scriptstyle\mathrm{I}$ is entirely confined within the inner star-forming disc, and that its kinematics is coincident with that of the CO. The cold gas disc is now well settled, which suggests that the galaxy has not been affected by any environmental interactions in the last $\sim1~$Gyr. The star formation history derived from the Fornax3D data shows that both the inner and outer disc experienced a burst of star formation $\sim5$ Gyr ago, followed by rapid quenching in the outer disc and by slow quenching in the inner disc, which continues forming stars to this day. We claim that NGC$~$1436 has begun to effectively interact with the cluster environment 5$~$Gyr ago, when a combination of gravitational and hydrodynamical interactions caused the temporary enhancement of the star-formation rate. Furthermore, due to the weaker gravitational binding $\textrm{H}\scriptstyle\mathrm{I}$ was stripped from the outer disc, causing its rapid quenching. At the same time, accretion of gas onto the inner disc stopped, causing slow quenching in this region.

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A. Loni, P. Serra, M. Sarzi, et. al.
Thu, 11 May 23
13/55

Comments: N/A

Obscured AGN enhancement in galaxy pairs at cosmic noon: evidence from a probabilistic treatment of photometric redshifts [GA]

http://arxiv.org/abs/2305.05692


Observations of the nearby universe reveal an increasing fraction of active galactic nuclei (AGN) with decreasing projected separation for close galaxy pairs, relative to control galaxies. This implies galaxy interactions play a role in enhancing AGN activity. However, the picture at higher redshift is less established, partly due to limited spectroscopic redshifts. We combine spectroscopic surveys with photometric redshift probability distribution functions for galaxies in the CANDELS and COSMOS surveys, to produce the largest ever sample of galaxy pairs used in an AGN fraction calculation for cosmic noon ($0.5<z<3$). We present a new technique for assessing galaxy pair probability (based on line-of-sight velocities +/-1000 km/s) from photometric redshift posterior convolutions and use these to produce weighted AGN fractions. Over projected separations 5-100kpc we find no evidence for enhancement, relative to isolated control galaxies, of X-ray (L_X > 10^42 erg/s) or infrared-selected AGN in major (mass ratios up to 4:1) or minor (4:1 to 10:1) galaxy pairs. However, defining the most obscured AGN as those detected in the infrared but not in X-rays, we observe a trend of increasing obscured AGN enhancement at decreasing separations. The peak enhancement, relative to isolated controls, is a factor of 2.08+/-0.61 for separations <25kpc. Our simulations with mock data, indicates this could be a lower limit of the true enhancement. If confirmed with improved infrared imaging (e.g., with JWST) and redshifts (e.g., with forthcoming multi-object spectrograph surveys), this would suggest that galaxy interactions play a role in enhancing the most obscured black hole growth at cosmic noon.

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S. Dougherty, C. Harrison, D. Kocevski, et. al.
Thu, 11 May 23
17/55

Comments: Accepted for publication in MNRAS

Characterizing cool, neutral gas and ionized metals in the outskirts of low-z galaxy clusters [GA]

http://arxiv.org/abs/2305.05698


We present the first statistical detection of cool, neutral gas in the outskirts of low-z galaxy clusters using a sample of 3191 z $\approx$0.2 background quasar – foreground cluster pairs with a median cluster mass of $\sim 10^{14.2}$ M_sun by cross-matching the Hubble Spectroscopic Legacy Archive quasar catalog with optically- and SZ-selected cluster catalogs. We detect significant Lya, marginal CIV, but no OVI absorption in the median stacked spectra with rest-frame equivalent widths (REWs) of 0.043$\pm$0.006A, 0.020$\pm$0.007A, and <0.006A (3$\sigma$) for our sample with a median impact parameter ($\rho_{cl}$) of $\approx$5 Mpc (median $\rho_{cl}$/$R_{500}$ $\approx$7 ). The Lya REW shows a declining trend with increasing $\rho_{cl}$ ($\rho_{cl}$ / $R_{500}$) which is well explained by a power-law with a slope of -0.74 (-0.60). The covering fractions measured for Lya, CIV and OVI in cluster outskirts are significantly lower compared to the circumgalatic medium (CGM). We find that the CGM of galaxies residing in cluster outskirts is considerably deficient in neutral gas compared to their field counterparts. This effect is more pronounced for galaxies that are closer to cluster centers or that are in massive clusters. We argue that the cool gas detected in cluster outskirts arises from the circumgalactic gas stripped from cluster galaxies and to large-scale filaments feeding the clusters with cool gas.

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S. Mishra, S. Muzahid, S. Dutta, et. al.
Thu, 11 May 23
22/55

Comments: 17 pages, 4 tables, 9 figures. Submitted to MNRAS

A Bayesian chemical evolution model of the DustPedia Galaxy M74 [GA]

http://arxiv.org/abs/2305.05680


We introduce a new, multi-zone chemical evolution model of the DustPedia galaxy M74, calibrated by means of MCMC methods.
We take into account the observed stellar and gas density profiles and use Bayesian analysis to constrain two fundamental parameters characterising the gas accretion and star formation timescale, i.e. the infall timescale tau and the SF efficiency nu, respectively, as a function of galactocentric radius R. Our analysis supports an infall timescale increasing with R and a star formation efficiency decreasing with R, thus supporting an ‘Inside-Out’ formation for M74. For both tau and nu, we find a weaker radial dependence than in the Milky Way.
We also investigate the dust content of M74, comparing the observed dust density profile with the results of our chemical evolution models. Various prescriptions have been considered for two key parameters, i.e. the typical dust accretion timescale and the mass of gas cleared out of the dust by a supernova remnant, regulating the dust growth and destruction rate, respectively. Two models with a different current balance between destruction and accretion, i.e. with equilibrium and dominion of accretion over destruction, can equally reproduce the observed dust profile of M74. This outlines the degeneracy between these parameters in shaping the interstellar dust content in galaxies. Our methods will be extended to more DustPedia galaxies to shed more light on the relative roles of dust production and destruction.

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F. Calura, M. Palla, L. Morselli, et. al.
Thu, 11 May 23
27/55

Comments: MNRAS, accepted for publication, 19 pages, 14 figures

A Local Universe model for constrained simulations [CEA]

http://arxiv.org/abs/2305.05694


The aim of cosmological simulations is to reproduce the properties of the observed Universe, serving as tools to test structure and galaxy formation models. Constrained simulations of our local cosmological region up to a few hundred Mpc/h , the local Universe, are designed to reproduce the actual cosmic web of structures as observed. A question that often arises is how to judge the quality of constrained simulations against the observations of the Local Universe. Here we introduce the Local Universe model (LUM), a new methodology, whereby many constrained simulations can be judged and the ”best” initial conditions can be identified. By characterising the Local Universe as a set of rich clusters, the model identifies haloes that serve as simulated counterparts to the observed clusters. Their merit is determined against a null hypothesis, the probability that such a counterpart could be identified in a random, unconstrained simulation. This model is applied to 100 constrained simulations using the Cosmicflows-3 data. Cluster counterparts are found for all constrained simulations, their distribution of separation from the true observed cluster position and their mass distribution are investigated. Lastly, the ”best” constrained simulation is selected using the LUM and discussed in more detail.

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S. Pfeifer, A. Valade, S. Gottlöber, et. al.
Thu, 11 May 23
30/55

Comments: 10 pages, 8 figures, submitted to MNRAS

Case A or Case B? The effective recombination coefficient in gas clouds of arbitrary optical thickness [GA]

http://arxiv.org/abs/2305.05764


In calculations of the ionization state, one is often forced to choose between the Case A recombination coefficient $\alpha_{\rm A}$ (sum over recombinations to all hydrogen states) or the Case B recombination coefficient $\alpha_{\rm B}$ (sum over all hydrogen states except the ground state). If the cloud is optically thick to ionizing photons, $\alpha_{\rm B}$ is usually adopted on the basis of the “on-the-spot” approximation, wherein recombinations to the ground state are ignored because they produce ionizing photons absorbed nearby. In the opposite case of an optically thin cloud, one would expect the Case A recombination coefficient to better describe the effective recombination rate in the cloud. In this paper, I derive an analytical expression for the effective recombination coefficient in a gas cloud of arbitrary optical thickness which transitions from $\alpha_{\rm A}$ to $\alpha_{\rm B}$ as the optical thickness increases. The results can be readily implemented in numerical simulations and semi-analytical calculations.

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O. Nebrin
Thu, 11 May 23
31/55

Comments: 4 pages, 1 figure. Accepted for publication in RNAAS

Gravitational Wave Peeps from EMRIs and their Implication for LISA Signal Confusion Noise [CL]

http://arxiv.org/abs/2305.05793


Scattering events around a supermassive black hole will occasionally toss a stellar-mass compact object into an orbit around the supermassive black hole, beginning an extreme mass ratio inspiral. The early stages of such a highly eccentric orbit will not produce detectable gravitational waves as the source will only be in a suitable frequency band briefly when it is close to periapsis during each long-period orbit. This burst of emission, firmly in the millihertz band is the gravitational wave peep. While a single peep is not likely to be detectable, if we consider an ensemble of such subthreshold sources, spread across the universe, together they produce an unresolvable background noise that may obscure sources otherwise detectable by the Laser Interferometer Space Antenna, the proposed space-based gravitational wave detector. Previous studies of the extreme mass ratio burst signal confusion background focused more on parabolic orbits going very near the supermassive black hole and on events near the galactic center. We seek to improve this characterization by implementing numerical kludge waveforms that can calculate highly eccentric orbits with relativistic effects focusing on orbits which are farther away from the supermassive black hole and thus less likely to be detectable on their own, but will otherwise contribute to the background signal confusion noise. Here we present the waveforms and spectra of the gravitational wave peeps generated from recent calculations of extreme mass ratio inspirals/bursts capture parameters and discuss how these can be used to estimate the signal confusion noise generated by such events.

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D. Oliver, A. Johnson, J. Berrier, et. al.
Thu, 11 May 23
46/55

Comments: 10 pages, 7 figures

Physics and Chemistry of Radiation Driven Cloud Evolution. [C II] Kinematics of IC 59 and IC 63 [GA]

http://arxiv.org/abs/2305.05719


We used high-resolution [C II] 158 $\mu$m mapping of two nebulae IC 59 and IC 63 from SOFIA/upGREAT in conjunction with ancillary data on the gas, dust, and polarization to probe the kinematics, structure, and magnetic properties of their photo-dissociation regions (PDRs). The nebulae are part of the Sh 2-185 H II region illuminated by the B0 IVe star $\gamma$ Cas. The velocity structure of each PDR changes with distance from $\gamma$ Cas, consistent with driving by the radiation. Based on previous FUV flux measurements of, and the known distance to $\gamma$ Cas along with the predictions of 3D distances to the clouds, we estimated the FUV radiation field strength (G0) at the clouds. Assuming negligible extinction between the star and clouds, we find their 3D distances from $\gamma$ Cas. For IC 63, our results are consistent with earlier estimates of distance from Andersson et al. (2013), locating the cloud at 2 pc from $\gamma$ Cas, at an angle of 58 to the plane of the sky, behind the star. For IC 59, we derive a distance of 4.5 pc at an angle of 70 in front of the star. We do not detect any significant correlation between the orientation of the magnetic field (Soam et al. 2017) and the velocity gradients of [C II] gas, indicating a moderate magnetic field strength. The kinetic energy in IC 63 is estimated to be order of ten higher than the magnetic energies. This suggests that kinetic pressure in this nebula is dominant.

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M. Caputo, A. Soam, B. Andersson, et. al.
Thu, 11 May 23
51/55

Comments: N/A

The LOFAR Two-metre Sky Survey Deep Fields Data Release 1: V. Survey description, source classifications and host galaxy properties [GA]

http://arxiv.org/abs/2305.05782


Source classifications, stellar masses and star formation rates are presented for 80,000 radio sources from the first data release of the Low Frequency Array Two-metre Sky Survey (LoTSS) Deep Fields, which represents the widest deep radio survey ever undertaken. Using deep multi-wavelength data spanning from the ultraviolet to the far-infrared, spectral energy distribution (SED) fitting is carried out for all of the LoTSS-Deep host galaxies using four different SED codes, two of which include modelling of the contributions from an active galactic nucleus (AGN). Comparing the results of the four codes, galaxies that host a radiative AGN are identified, and an optimised consensus estimate of the stellar mass and star-formation rate for each galaxy is derived. Those galaxies with an excess of radio emission over that expected from star formation are then identified, and the LoTSS-Deep sources are divided into four classes: star-forming galaxies, radio-quiet AGN, and radio-loud high-excitation and low-excitation AGN. Ninety-five per cent of the sources can be reliably classified, of which more than two-thirds are star-forming galaxies, ranging from normal galaxies in the nearby Universe to highly-starbursting systems at z>4. Star-forming galaxies become the dominant population below 150-MHz flux densities of about 1 mJy, accounting for 90 per cent of sources at a 150-MHz flux density of 100 microJy. Radio-quiet AGN comprise around 10 per cent of the overall population. Results are compared against the predictions of the SKADS and T-RECS radio sky simulations, and improvements to the simulations are suggested.

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P. Best, R. Kondapally, W. Williams, et. al.
Thu, 11 May 23
54/55

Comments: Accepted for publication in MNRAS. Catalogues available at www.lofar-surveys.org/deepfields.html. 27 pages

QLUSTER: quick clusters of merging binary black holes [HEAP]

http://arxiv.org/abs/2305.04987


This short document illustrates QLUSTER: a toy model for populations of binary black holes in dense astrophysical environments. QLUSTER is a simple tool to investigate the occurrence and properties of hierarchical black-hole mergers detectable by gravitational-wave interferometers. QLUSTER is not meant to rival the complexity of state-of-the-art population synthesis and N-body codes but rather provide a fast, approximate, and easy-to-interpret framework to investigate some of the key ingredients of the problem. These include the binary pairing probability, the escape speed of the host environment, and the merger generation. We also introduce the “hierarchical-merger efficiency” — an estimator that quantifies the relevance of hierarchical black-hole mergers in a given astrophysical environment.

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D. Gerosa and M. Mould
Wed, 10 May 23
2/65

Comments: Contribution to the 2023 Gravitation session of the 57th Rencontres de Moriond

Metal-poor stars observed with the Magellan Telescope. IV. Neutron-capture element signatures in 27 main-sequence stars [GA]

http://arxiv.org/abs/2305.05363


Based on high-resolution spectra obtained with Magellan/MIKE, we present a chemo-dynamical analysis for 27 near main-sequence turnoff metal-poor stars, including 20 stars analyzed for the first time. The sample spans a range in [Fe/H] from -2.5 to -3.6, with 44% having [Fe/H] <-2.9. We derived chemical abundances for 17 elements, including strontium and barium. We derive Li abundances for the sample, which are in good agreement with the “Spite Plateau” value. A dozen of stars are carbon-enhanced. The lighter elements (Z<30) generally agree well with those of other low-metallicity halo stars. This broadly indicates chemically homogeneous gas at the earliest times. Of the neutron-capture elements, we only detected strontium and barium. We used the [Sr/Ba] vs. [Ba/Fe] diagram to classify metal-poor stars into five populations based on their observed ratios. We find HE0232-3755 to be a likely main r-process star, and HE2214-6127 and HE2332-3039 to be limited-r stars. CS30302-145, HE2045-5057, and CD-24 17504 plausibly originated in long-disrupted early dwarf galaxies as evidenced by their [Sr/Ba] and [Ba/Fe] ratios. We also find that the derived [Sr/H] and [Ba/H] values for CD-24 17504 are not inconsistent with the predicted yields of the s-process in massive rotating low-metallicity stars models. Further theoretical explorations will be helpful to better understand the earliest mechanisms and time scales of heavy element production for comparison with these and other observational abundance data. Finally, we investigate the orbital histories of our sample stars. Most display halo-like kinematics although three stars (CS29504-018, HE0223-2814, and HE2133-0421) appear to be disk-like in nature. This confirms the extragalactic origin for CS30302-145, HE2045-5057, and, in particular, CD-24 17504 which likely originated from a small accreted stellar system as one of the oldest stars.

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M. Mardini, A. Frebel, L. Betre, et. al.
Wed, 10 May 23
4/65

Comments: N/A

Shocks Power Tidal Disruption Events [HEAP]

http://arxiv.org/abs/2305.05333


Accretion of debris seems to be the natural mechanism to power the radiation emitted during a tidal disruption event (TDE), in which a supermassive black hole tears apart a star. However, this requires the prompt formation of a compact accretion disk. Here, using a fully relativistic global simulation for the long-term evolution of debris in a TDE with realistic initial conditions, we show that at most a tiny fraction of the bound mass enters such a disk on the timescale of observed flares. To “circularize” most of the bound mass entails an increase in the binding energy of that mass by a factor $\sim 30$; we find at most an order unity change. Our simulation suggests it would take a time scale comparable to a few tens of the characteristic mass fallback time to dissipate enough energy for “circularization”. Instead, the bound debris forms an extended eccentric accretion flow with eccentricity $\simeq 0.4-0.5$ by $\sim 2$ fallback times. Although the energy dissipated in shocks in this large-scale flow is much smaller than the “circularization” energy, it matches the observed radiated energy very well. Nonetheless, the impact of shocks is not strong enough to unbind initially bound debris into an outflow.

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T. Ryu, J. Krolik, T. Piran, et. al.
Wed, 10 May 23
5/65

Comments: 20 pages, 16 figures, Submitted to ApJ, comments welcome!

RAM: Rapid Advection Algorithm on Arbitrary Meshes [IMA]

http://arxiv.org/abs/2305.05362


The study of many astrophysical flows requires computational algorithms that can capture high Mach number flows, while resolving a large dynamic range in spatial and density scales. In this paper we present a novel method, RAM: Rapid Advection Algorithm on Arbitrary Meshes. RAM is a time-explicit method to solve the advection equation in problems with large bulk velocity on arbitrary computational grids. In comparison with standard up-wind algorithms, RAM enables advection with larger time steps and lower truncation errors. Our method is based on the operator splitting technique and conservative interpolation. Depending on the bulk velocity and resolution, RAM can decrease the numerical cost of hydrodynamics by more than one order of magnitude. To quantify the truncation errors and speed-up with RAM, we perform one and two-dimensional hydrodynamics tests. We find that the order of our method is given by the order of the conservative interpolation and that the effective speed up is in agreement with the relative increment in time step. RAM will be especially useful for numerical studies of disk-satellite interaction, characterized by high bulk orbital velocities, and non-trivial geometries. Our method dramatically lowers the computational cost of simulations that simultaneously resolve the global disk and well inside the Hill radius of the secondary companion.

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P. Benítez-Llambay, L. Krapp, X. Ramos, et. al.
Wed, 10 May 23
14/65

Comments: 15 pages, 7 figures. Submitted to ApJ. Comments are welcome

A high-redshift calibration of the [OI]-to-HI conversion factor in star-forming galaxies [GA]

http://arxiv.org/abs/2305.05213


The assembly and build-up of neutral atomic hydrogen (HI) in galaxies is one of the most fundamental processes in galaxy formation and evolution. Studying this process directly in the early universe is hindered by the weakness of the hyperfine 21-cm HI line transition, impeding direct detections and measurements of the HI gas masses ($M_{\rm HI}$). Here we present a new method to infer $M_{\rm HI}$ of high-redshift galaxies using neutral, atomic oxygen as a proxy. Specifically, we derive metallicity-dependent conversion factors relating the far-infrared [OI]-$63\mu$m and [OI]-$145\mu$m emission line luminosities and $M_{\rm HI}$ in star-forming galaxies at $z\approx 2-6$ using gamma-ray bursts (GRBs) as probes. We substantiate these results by observations of galaxies at $z\approx 0$ with direct measurements of $M_{\rm HI}$ and [OI]-$63\mu$m and [OI]-$145\mu$m in addition to hydrodynamical simulations at similar epochs. We find that the [OI]${\rm 63\mu m}$-to-HI and [OI]${\rm 145\mu m}$-to-HI conversion factors universally appears to be anti-correlated with the gas-phase metallicity. The high-redshift GRB measurements further predict a mean ratio of $L_{\rm [OI]-63\mu m} / L_{\rm [OI]-145\mu m}=1.55\pm 0.12$ and reveal generally less excited [CII]. The $z \approx 0$ galaxy sample also shows systematically higher $\beta_{\rm [OI]-63\mu m}$ and $\beta_{\rm [OI]-145\mu m}$ conversion factors than the GRB sample, indicating either suppressed [OI] emission in local galaxies or more extended, diffuse HI gas reservoirs traced by the HI 21-cm. Finally, we apply these empirical calibrations to the few high-redshift detections of [OI]-$63\mu$m and [OI]-$145\mu$m line transitions from the literature and further discuss the applicability of these conversion factors to probe the HI gas content in the dense, star-forming ISM of galaxies at $z\gtrsim 6$, well into the epoch of reionization.

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S. Wilson, K. Heintz, P. Jakobsson, et. al.
Wed, 10 May 23
16/65

Comments: Submitted to A&A. Comments welcome

The Dragonfly Galaxy. III. Jet-brightening of a High-redshift Radio Source Caught in a Violent Merger of Disk Galaxies [GA]

http://arxiv.org/abs/2305.05564


The Dragonfly Galaxy (MRC 0152-209), the most infrared-luminous radio galaxy at redshift z~2, is a merger system containing a powerful radio source and large displacements of gas. We present kpc-resolution data from ALMA and the VLA of carbon monoxide (6-5), dust, and synchrotron continuum, combined with Keck integral-field spectroscopy. We find that the Dragonfly consists of two galaxies with rotating disks that are in the early phase of merging. The radio jet originates from the northern galaxy and brightens when it hits the disk of the southern galaxy. The Dragonfly Galaxy therefore likely appears as a powerful radio galaxy because its flux is boosted into the regime of high-z radio galaxies by the jet-disk interaction. We also find a molecular outflow of (1100 $\pm$ 550) M${\odot}$/yr associated with the radio host galaxy, but not with the radio hot-spot or southern galaxy, which is the galaxy that hosts the bulk of the star formation. Gravitational effects of the merger drive a slower and longer lived mass displacement at a rate of (170 $\pm$ 40) M${\odot}$/yr, but this tidal debris contain at least as much molecular gas mass as the much faster outflow, namely M(H2) = (3 $\pm$ 1) x 10$^9$ (alpha(CO)/0.8) M$_{\odot}$. This suggests that both the AGN-driven outflow and mass transfer due to tidal effects are important in the evolution of the Dragonfly system. The Keck data show Ly$\alpha$ emission spread across 100 kpc, and CIV and HeII emission across 35 kpc, confirming the presence of a metal-rich and extended circumgalactic medium previously detected in CO(1-0).

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S. Lebowitz, B. Emonts, D. Terndrup, et. al.
Wed, 10 May 23
17/65

Comments: Accepted for publication in ApJ (15 pages, 9 figures)

ALMA High-Level Data Products: Submillimetre counterparts of SDSS quasars in the ALMA footprint [GA]

http://arxiv.org/abs/2305.05173


The Atacama Large Millimetre/submillimetre Array (ALMA) is the world’s most advanced radio interferometric facility, producing science data with an average rate of about 1 TB per day. After a process of calibration, imaging and quality assurance, the scientific data are stored in the ALMA Science Archive (ASA), along with the corresponding raw data, making the ASA an invaluable resource for original astronomical research. Due to their complexity, each ALMA data set has the potential for scientific results that go well beyond the ideas behind the original proposal that led to each observation. For this reason, the European ALMA Regional Centre initiated the High-Level Data Products initiative to develop science-oriented data products derived from data sets publicly available in the ASA, that go beyond the formal ALMA deliverables. The first instance of this initiative is the creation of a catalogue of submillimetre (submm) detections of Sloan Digital Sky Survey (SDSS) quasars from the SDSS Data Release 14 that lie in the aggregate ALMA footprint observed since ALMA Cycle 0. The ALMA fluxes are extracted in an automatic fashion, using the ALMA Data Mining Toolkit. All extractions above a signal-to-noise cut of 3.5 are considered, they have been visually inspected and the reliable detections are presented in a catalogue of 376 entries, corresponding to 275 unique quasars. Interesting targets found in the process, i.e. lensed or jetted quasars as well as quasars with nearby submm counterparts are highlighted, to facilitate further studies or potential follow up observations.

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A. Wong, E. Hatziminaoglou, A. Borkar, et. al.
Wed, 10 May 23
20/65

Comments: N/A

The odd bunch: chrono-chemo-dynamics of sixteen unusual stars from Kepler [SSA]

http://arxiv.org/abs/2305.05024


In this study we combine asteroseismic, spectroscopic and kinematic information to perform a detailed analysis of a sample of 16 stars from the Kepler field. Our selection focuses on stars that appear to contradict Galactic chemical evolution models: young and $\alpha$-rich, old and metal-rich, as well as other targets with unclear classification in past surveys. Kinematics are derived from Gaia DR3 parallaxes and proper motions, and high-resolution spectra from HIRES/Keck are used to calculate chemical abundances for over 20 elements. This information is used to perform careful checks on asteroseismic masses and ages derived via grid-based modelling. Among the seven stars previously classified as young and $\alpha$-rich, only one seems to be an unambiguously older object masking its true age. We confirm the existence of two very old ($\geq$11 Gyr), super metal rich ($\geq$0.1 dex) giants. These two stars have regular thin disc chemistry and in-plane solar circle orbits which fit well in the picture of radial migration via the churning mechanism. The alternative explanation that these stars have younger ages would require mass-loss rates which strongly increases with increasing metallicity. Finally, we suggest further investigations to explore the suitability of Zn as a chemical clock in red giants.

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A. Puls, L. Casagrande, S. Monty, et. al.
Wed, 10 May 23
21/65

Comments: 10 pages, 7 figures, accepted for publication in MNRAS

Exploring the nature of UV-bright $z \gtrsim 10$ galaxies detected by JWST: star formation, black hole accretion, or a non universal IMF? [GA]

http://arxiv.org/abs/2305.04944


We use the Cosmic Archaeology Tool (CAT) semi-analytical model to explore the contribution of Population (Pop) III/II stars and active galactic nuclei (AGNs) to the galaxy UV luminosity function (LF) evolution at $4 \leq z \leq 20$. We compare in particular with recent JWST data in order to explore the apparent tension between observations and theoretical models in the number density of bright galaxies at $z \gtrsim 10$. The model predicts a star formation history dominated by UV faint ($M_{\rm UV} > – 18$) galaxies, with a Pop III contribution of $\lesssim 10\%$ ($\lesssim 0.5\%$) at $z \simeq 20$ ($z \simeq 10$). Stars are the primary sources of cosmic reionization, with $5 – 10 \%$ of ionizing photons escaping into the intergalatic medium at $5 \leq z \leq 10$, while the contribution of unobscured AGNs becomes dominant only at $z \lesssim 5$. The predicted stellar and AGN UV LFs reproduce the observational data at $5 \lesssim z \lesssim 9 – 10$. At higher redshift, CAT predicts a steeper evolution in the faint-end slope ($M_{\rm UV} > – 18$), and a number density of bright galaxies ($M_{\rm UV} \simeq -20$) consistent with data at $z \sim 10 – 11$, but smaller by 0.8 dex at $z \sim 12 – 13$, and 1.2 dex at $z \sim 14 – 16$, when compared to the values estimated by recent studies. Including the AGN emission does not affect the above findings, as AGNs contribute at most to $\lesssim 10 \%$ of the total UV luminosity at $M_{\rm UV} < – 19$ and $z \gtrsim 10$. Interestingly, considering a gradual transition in the stellar IMF, modulated by metallicity and redshift as suggested by recent simulations, the model agrees with JWST data at $z \sim 12 – 13$, and the disagreement at $z \sim 14 – 16$ is reduced to 0.5 dex.

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A. Trinca, R. Schneider, R. Valiante, et. al.
Wed, 10 May 23
24/65

Comments: 18 pages, 9 figures. Submitted to MNRAS. Comments are welcome

CLEAR: The Morphological Evolution of Galaxies in the Green Valley [GA]

http://arxiv.org/abs/2305.04953


Quiescent galaxies having more compact morphologies than star-forming galaxies has been a consistent result in the field of galaxy evolution. What is not clear is at what point this divergence happens, i.e. when do quiescent galaxies become compact, and how big of a role does the progenitor effect play in this result? Here we aim to model the morphological and star-formation histories of high redshift (0.8 $<$ z $<$ 1.65) massive galaxies (log(M/M$\odot$) $>$ 10.2) with stellar population fits using HST/WFC3 G102 and G141 grism spectra plus photometry from the CLEAR (CANDELS Lyman-alpha Emission at Reionization) survey, constraining the star-formation histories for a sample of $\sim$ 400 massive galaxies using flexible star-formation histories. We develop a novel approach to classifying galaxies by their formation activity in a way that highlights the green valley population, by modeling the specific star-formation rate distributions as a function of redshift and deriving the probability that a galaxy is quiescent (PQ). Using PQ and our flexible star-formation histories we outline the evolutionary paths of our galaxies in relation to stellar mass, Sersic index, $R_{eff}$, and stellar mass surface density. We find that galaxies show no appreciable stellar mass growth after entering the green valley (a net decrease of 4$\%$) while their stellar mass surface densities increase by $\sim$ 0.25 dex. Therefore galaxies are becoming compact during the green valley and this is due to increases in Sersic index and decreases in $R_{eff}$.

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V. Estrada-Carpenter, C. Papovich, I. Momcheva, et. al.
Wed, 10 May 23
26/65

Comments: 17 pages, 10 figures, submitted to ApJ

Implementation of chemistry in the Athena++ code [GA]

http://arxiv.org/abs/2305.04965


Chemistry plays a key role in many aspects of astrophysical fluids. Atoms and molecules are agents for heating and cooling, determine the ionization fraction, serve as observational tracers, and build the molecular foundation of life. We present the implementation of a chemistry module in the publicly available magneto-hydrodynamic code Athena++. We implement several chemical networks and heating and cooling processes suitable for simulating the interstellar medium (ISM). A general chemical network framework in the KIDA format is also included, allowing the user to easily implement their own chemistry. Radiation transfer and cosmic-ray ionization are coupled with chemistry and solved with the simple six-ray approximation. The chemical and thermal processes are evolved as a system of coupled ODEs with an implicit solver from the CVODE library. We perform and present a series of tests to ensure the numerical accuracy and convergence of the code. Many tests combine chemistry with gas dynamics, including comparisons with analytic solutions, 1D problems of the photo-dissociation regions and shocks, and realistic 3D simulations of the turbulent ISM. We release the code with the new public version of Athena++, aiming to provide a robust and flexible code for the astrochemical simulation community.

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M. Gong, K. Ho, J. Stone, et. al.
Wed, 10 May 23
27/65

Comments: N/A

Constraining SIDM cross section models with a joint analysis of galaxies and clusters [CEA]

http://arxiv.org/abs/2305.05067


One necessary step for probing the nature of self-interacting dark matter (SIDM) particles with astrophysical observations is to pin down any possible velocity dependence in the SIDM cross section. Major challenges for achieving this goal include eliminating, or mitigating, the impact of the baryonic components and tidal effects within the dark matter halos of interest — the effects of these processes can be highly degenerate with those of dark matter self-interactions at small scales. In this work we select 9 isolated galaxies and brightest cluster galaxies (BCGs) with baryonic components small enough such that the baryonic gravitational potentials do not significantly influence the halo gravothermal evolution processes. We then constrain the parameters of a cross section model $\sigma(v)=\sigma_0/(1+v^2/\omega^2)^2$ with the measured rotation curves and stellar kinematics through the gravothermal fluid formalism and isothermal method. We are able to constrain a best-fit double power-law result with the gravothermal fluid formalism $\log(\sigma_0/[\mathrm{cm^2/g}])=2.6/[(\log(\omega/[\mathrm{km/s}])/1.9)^{0.85}+(\log(\omega/[\mathrm{km/s}])/1.9)^{5.5}]-1.1$ with $\log(\omega/[\mathrm{km/s}])\leq3.7$ and a scatter of 0.5 dex at a 68% confidence level. The constraint given by the isothermal model is $\log(\sigma_0/[\mathrm{cm^2/g}])=3.9/[(\log(\omega/[\mathrm{km/s}])/1.6)^{0.29}+(\log(\omega/[\mathrm{km/s}])/1.6)^{5.1}]-0.34$ with $1.4\leq\log(\omega/[\mathrm{km/s}])\leq3.5$ and a scatter of 0.34 dex at 68% confidence level. Cross sections constrained by the two methods are consistent at $2\sigma$ confidence level, but the isothermal method prefers cross sections greater than the gravothermal approach constraints by a factor of $\sim4$.

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S. Yang, F. Jiang, A. Benson, et. al.
Wed, 10 May 23
28/65

Comments: 14 pages, 10 figures

HSC-CLAUDS survey: The star formation rate functions since z ~ 2 and comparison with hydrodynamical simulations [GA]

http://arxiv.org/abs/2305.05504


Star formation rate functions (SFRFs) give an instantaneous view of the distribution of star formation rates (SFRs) in galaxies at different epochs. They are a complementary and more stringent test for models than the galaxy stellar mass function, which gives an integrated view of the past star formation activity. However, the exploration of SFRFs has been limited thus far due to difficulties in assessing the SFR from observed quantities and probing the SFRF over a wide range of SFRs. We overcome these limitations thanks to an original method that predicts the infrared luminosity from the rest-frame UV/optical color of a galaxy and then its SFR over a wide range of stellar masses and redshifts. We applied this technique to the deep imaging survey HSC-CLAUDS combined with near-infrared and UV photometry. We provide the first SFR functions with reliable measurements in the high- and low-SFR regimes up to $z=2$ and compare our results with previous observations and four state-of-the-art hydrodynamical simulations.

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V. Picouet, S. Arnouts, E. Floch, et. al.
Wed, 10 May 23
29/65

Comments: 29 pages, 19 figures

Fisher matrix forecasts on the astrophysics of galaxies during the epoch of reionisation from the 21-cm power spectra [CEA]

http://arxiv.org/abs/2305.05104


The hyperfine 21-cm transition of neutral hydrogen from the early Universe ($z>5$) is a sensitive probe of the formation and evolution of the first luminous sources. Using the Fisher matrix formalism we explore the complex and degenerate high-dimensional parameter space associated with the high-$z$ sources of this era and forecast quantitative constraints from a future 21-cm power spectrum (21-cm PS) detection. This is achieved using MERAXES, a coupled semi-analytic galaxy formation model and reionisation simulation, applied to an $N$-body halo merger tree with a statistically complete population of all atomically cooled galaxies out to $z\sim20$. Our mock observation assumes a 21-cm detection spanning $z \in [5, 24]$ from a 1000 h mock observation with the forthcoming Square Kilometre Array and is calibrated with respect to ultraviolet luminosity functions (UV LFs) at $z\in[5, 10]$, the optical depth of CMB photons to Thompson scattering from Planck, and various constraints on the IGM neutral fraction at $z > 5$. In this work, we focus on the X-ray luminosity, ionising UV photon escape fraction, star formation and supernova feedback of the first galaxies. We demonstrate that it is possible to recover 5 of the 8 parameters describing these properties with better than $50$ per cent precision using just the 21-cm PS. By combining with UV LFs, we are able to improve our forecast, with 5 of the 8 parameters constrained to better than 10 per cent (and all below 50 per cent).

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S. Balu, B. Greig and J. Wyithe
Wed, 10 May 23
32/65

Comments: 13 pages, 5 figures (+1 appendix), submitted to MNRAS, comments welcome

Binary neutron star populations in the Milky Way [HEAP]

http://arxiv.org/abs/2305.04955


Galactic binary neutron stars (BNSs) are a unique laboratory to probe the evolution of BNSs and their progenitors. Here, we use a new version of the population synthesis code SEVN to evolve the population of Galactic BNSs, by modeling the spin up and down of pulsars self-consistently. We analyze the merger rate $\mathcal{R}{\rm MW}$, orbital period $P{\rm orb}$, eccentricity $e$, spin period $P$, and spin period derivative $\dot{P}$ of the BNS population. Values of the common envelope parameter $\alpha=1 – 3$ and an accurate model of the Milky Way star formation history best reproduce the BNS merger rate in our Galaxy ($\mathcal{R}{\rm MW}\approx{}30$ Myr$^{-1}$). We apply radio-selection effects to our simulated BNSs and compare them to the observed population. Using a Dirichlet process Gaussian mixture method, we evaluate the four-dimensional likelihood in the $(P{\rm orb}, e, P, \dot{P})$ space, by comparing our radio-selected simulated pulsars against Galactic BNSs. Our analysis favours an uniform initial distribution for both the magnetic field ($10^{10-13}$ G) and the spin period ($10-100$ ms). The implementation of radio selection effects is critical to match not only the spin period and period derivative, but also the orbital period and eccentricity of Galactic BNSs. According to our fiducial model, the Square Kilometre Array will detect $\sim 20$ new BNSs in the Milky Way.

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C. Sgalletta, G. Iorio, M. Mapelli, et. al.
Wed, 10 May 23
33/65

Comments: 20 pages, 8 figures, 8 tables, comments welcome

Constraining The Milky Way Bar Length using Hercules and Gaia DR3 [GA]

http://arxiv.org/abs/2305.04981


The distribution of moving groups in the solar neighborhood has been used to constrain dynamical properties of the Milky Way for decades. Unfortunately, the unique bimodality between the main mode (Hyades, Pleiades, Coma Berenices, and Sirius) and Hercules can be explained by two different bar models — via the outer Lindblad resonance of a short, fast bar, or via the corotation resonance of a long, slow bar. In this work, we break this degeneracy by using Gaia DR3 to explore the variation of Hercules across Galactic azimuth. We find that Hercules increases in $V_\phi$ and becomes stronger as we move towards the minor axis of the bar, and decreases in $V_\phi$ and becomes weaker as we move towards the major axis of the bar. This is in direct agreement with theoretical predictions of a long, slow bar model in which Hercules is formed by the corotation resonance with stars orbiting the bar’s L4/L5 Lagrange points.

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S. Lucchini, E. D’Onghia and J. Aguerri
Wed, 10 May 23
37/65

Comments: 5 pages, 4 figures, submitted

Stellar Collisions in Galactic Nuclei: Impact on Destructive Events Near a Supermassive Black Hole [GA]

http://arxiv.org/abs/2305.04997


Centers of galaxies host both a supermassive black hole and a dense stellar cluster. Such an environment should lead to stellar collisions, possibly at very high velocities so that the total energy involved is of the same order as supernovae explosions. We present a simplified numerical analysis of the destructive stellar collision rate in a cluster similar to that of the Milky Way. The analysis includes an effective average two-body relaxation Monte-Carlo scheme and general relativistic effects, as used by Sari and Fragione (2019), to which we added explicit tracking of local probabilities for stellar collisions. We also consider stars which are injected into the stellar cluster after being disrupted from a binary system by the supermassive black hole. Such stars are captured in the vicinity of the black hole and enhance the expected collision rate. In our results we examine the rate and energetic distribution function of high velocity stellar collisions, and compare them self-consistently with the other destructive processes which occur in the galactic center, namely tidal disruptions and extreme mass ratio inspirals.

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S. Balberg and G. Yassur
Wed, 10 May 23
38/65

Comments: 18 pages, 10 figures; submitted to ApJ

The Impact of Cosmic Variance on Inferences of Global Neutral Fraction Derived from Ly$α$ Luminosity Functions During Reionization [CEA]

http://arxiv.org/abs/2305.04949


We investigate the impact of field-to-field variation, deriving from cosmic variance, in measured Lyman-$\alpha$ emitter (LAE) luminosity functions (LFs) and this variation’s impact on inferences of the neutral fraction of the intergalactic medium (IGM) during reionization. We post-process a z=7 IGM simulation to populate the dark matter halos with LAEs. These LAEs have realistic UV magnitudes, Ly$\alpha$ fluxes, and Ly$\alpha$ line profiles. We calculate the attenuation of Ly$\alpha$ emission in universes with varying IGM neutral fraction, $\bar{\rm{x}}{\rm{HI}}$. In a $\bar{\rm{x}}{\rm{HI}}=0.3$ simulation, we perform 100 realizations of a mock 2 square degree survey with a redshift window $\Delta z = 0.5$ and flux limit $\rm{f}{Ly\alpha}>1\times10^{-17}:\rm{ergs}:: \rm{s}^{-1} : \rm{cm}^{-2}$; such a survey is typical in depth and volume of the largest LAE surveys conducted today. For each realization, we compute the LAE LF and use it to recover the input $\bar{\rm{x}}{\rm{HI}}$. Comparing the inferred values of $\bar{\rm{x}}{\rm{HI}}$ across the ensemble of the surveys, we find that cosmic variance, deriving from large-scale structure and variation in the neutral gas along the sightline, imposes a floor in the uncertainty of $\Delta \bar{\rm{x}}{\rm{HI}} \sim 0.2$ when $\bar{\rm{x}}{\rm{HI}}$ $=0.3$. We explore mitigation strategies to decrease this uncertainty, such as increasing the volume, decreasing the flux limit, or probing the volume with many independent fields. Increasing the area and/or depth of the survey does not mitigate the uncertainty, but composing a survey with many independent fields is effective. This finding highlights the best strategy for LAE surveys aiming at constraining $\bar{\rm{x}}{\rm{HI}}$ of the universe during reionization.

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S. Bruton, C. Scarlata, F. Haardt, et. al.
Wed, 10 May 23
39/65

Comments: 17 pages, 13 figures

Identification of interstellar cyanamide towards the hot molecular core G358.93-0.03 MM1 [GA]

http://arxiv.org/abs/2305.05578


The amide-related molecules are essential for the formation of the other complex bio-molecules and an understanding of the prebiotic chemistry in the interstellar medium (ISM). We presented the first detection of the rotational emission lines of the amide-like molecule cyanamide (NH${2}$CN) towards the hot molecular core G358.93$-$0.03 MM1 using the Atacama Large Millimeter/Submillimeter Array (ALMA). Using the rotational diagram model, the derived column density of NH${2}$CN towards the G358.93$-$0.03 MM1 was (5.9$\pm$2.5)$\times$10$^{14}$ cm$^{-2}$ with a rotational temperature of 100.6$\pm$30.4 K. The derived fractional abundance of NH${2}$CN towards the G358.93$-$0.03 MM1 with respect to H${2}$ was (4.72$\pm$2.0)$\times$10$^{-10}$, which is very similar to the existent three-phase warm-up chemical model abundances of NH${2}$CN. We compare the estimated abundance of NH${2}$CN towards G358.93$-$0.03 MM1 with other sources, and we observe the abundance of NH${2}$CN towards G358.93$-$0.03 MM1 is nearly similar to that of the sculptor galaxy NGC 253 and the low-mass protostars IRAS 16293-2422 B and NGC 1333 IRAS4A2. We also discussed the possible formation mechanisms of NH${2}$CN towards the hot molecular cores and hot corinos, and we find that the NH${2}$CN molecule was created in the grain-surfaces of G358.93-0.03 MM1 via the neutral-neutral reaction between NH${2}$ and CN.

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A. Mannna and S. Pal
Wed, 10 May 23
40/65

Comments: Published in Astrophysics and Space Science

Globular clusters in the central region of the Milky Way galaxy I. Bar influence on the orbit parameters according to Gaia EDR3 [GA]

http://arxiv.org/abs/2305.05012


The work is devoted to the analysis of the influence of the galactic bar on the orbital motion of globular clusters in the central region of the Galaxy. For this task, 45 globular clusters were selected, 34 of which belong to the bulge/bar and 11 to the disk. The most accurate astrometric data from the Gaia satellite (Vasiliev and Baumgardt, 2021), as well as new refined average distances (Baumgardt and Vasiliev, 2021), were used to form the 6D-phase space required for orbit integration. The orbits of globular clusters are obtained both in an axisymmetric potential and in a potential including a bar. In this case, the mass, rotation velocity, shape and scale length of the bar were varied. A comparison is made of such orbital parameters as apocentric and pericentric distances, eccentricity and maximum distance from the galactic plane. It is shown that the mass of the bar exerts the greatest influence on the orbital motion, which is expressed mainly in an increase in both the apocentric and pericentric distances in the vast majority of globular clusters. The eccentricities of the orbits in the overwhelming majority also change significantly, and there is a change both upward and downward, especially in the range of values from 0.2 to 0.8. The greatest changes in parameters are observed in globular clusters with high radial velocities and small pericentric distances. The change in orbital parameters depending on the bar rotation velocity is less pronounced. The influence of the geometric parameters of the bar is insignificant in the accepted range of their changes. Several examples show that globular clusters in the bulge are more affected by the bar than those belonging to the disk.

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A. Bajkova, A. Smirnov and V. Bobylev
Wed, 10 May 23
42/65

Comments: 29 pages, 10 figures, 6 tables

The HI gas fraction scaling relation of the Green Pea galaxies [GA]

http://arxiv.org/abs/2305.05167


Green Pea galaxies are compact galaxies with high star formation rates. However, limited samples of Green Pea galaxies have HI 21 cm measurements. Whether the HI gas fraction f_{HI} = M_{HI}/M_{} of Green Pea galaxies follows the existing scaling relations between the f_{HI} and NUV-r color or linear combinations of color and other physical quantities needs checking. Using archival data of HI 21cm observations, we investigate the scaling relation of the NUV-r color with the M_{HI}/M_{} of 38 Green Pea galaxies, including 17 detections and 21 non-detections. The HI to stellar mass ratios (f_{HI}) of Green Pea galaxies deviate from the polynomial form, where a higher HI gas fraction is predicted given the current NUV-r color, even with the emission lines removed. The blue sources (NUV-r<1) from the comparison sample (ALFALFA-SDSS) follow a similar trend. The HI gas fraction scaling relations with linear combination forms of -0.34(NUV-r) – 0.64 log(mu_{,z}) + 5.94 and -0.77 log mu_{,i} + 0.26 log SFR/M_{*}+8.53, better predict the HI gas fraction of the Green Pea galaxies. In order to obtain accurate linear combined forms, higher-resolution photometry from space-based telescopes is needed.

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S. Liu, A. Luo, W. Zhang, et. al.
Wed, 10 May 23
43/65

Comments: 15 pages, 7 figures, to be published in RAA

Low-Temperature Kinetics for the N + NO reaction: Experiment Guides the Way [GA]

http://arxiv.org/abs/2305.05305


The reaction N(4S) + NO -> O(3P) + N2 plays a pivotal role in the conversion of atomic to molecular nitrogen in dense interstellar clouds and in the atmosphere. Here we report a joint experimental and computational investigation of the N + NO reaction with the aim of providing improved constraints on its low temperature reactivity. Thermal rates were measured over the 50 to 296 K range in a continuous supersonic flow reactor coupled with pulsed laser photolysis and laser induced fluorescence for the production and detection of N(4S) atoms, respectively. With decreasing temperature, the experimentally measured reaction rate was found to monotonously increase up to a value of (6.6 +- 1.3) x 10-11 cm3 s-1 at 50 K. To confirm this finding, quasi-classical trajectory simulations were carried out on a previously validated, full-dimensional potential energy surface (PES). However, around 50 K the computed rates decreased which required re-evaluation of the reactive PES in the long-range part due to a small spurious barrier with height 40 K in the entrance channel. By exploring different correction schemes the measured thermal rates can be adequately reproduced, displaying a clear negative temperature dependence over the entire temperature range. The possible astrochemical implications of an increased reaction rate at low temperature are also discussed.

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K. Hickson, J. Veliz, D. Koner, et. al.
Wed, 10 May 23
45/65

Comments: 28 pages, 6 figures and 2 tables in the main article. 3 figures and 1 table in the supplementary information. Accepted for publication in PCCP

First observations of warm and cold methanol in Class 0/I proto-brown dwarfs [GA]

http://arxiv.org/abs/2305.04991


We present results from the first molecular line survey to search for the fundamental complex organic molecule, methanol (CH${3}$OH), in 14 Class 0/I proto-brown dwarfs (proto-BDs). IRAM 30-m observations over the frequency range of 92-116 GHz and 213-280 GHz have revealed emission in 14 CH${3}$OH transition lines, at upper state energy level, E${upper}\sim$7-49 K, and critical densities, $n{crit}$ of 10$^{5}$ to 10$^{9}$ cm$^{-3}$. The most commonly detected lines are at E${upper} <$ 20 K, while 11 proto-BDs also show emission in the higher excitation lines at E${upper}\sim$21-49 K and $n_{crit}\sim$10$^{5}$ to 10$^{8}$ cm$^{-3}$. In comparison with the brown dwarf formation models, the high excitation lines likely probe the warm ($\sim$25-50 K) corino region at $\sim$10-50 au in the proto-BDs, while the low-excitation lines trace the cold ($<$ 20 K) gas at $\sim$50-150 au. The column density for the cold component is an order of magnitude higher than the warm component. The CH${3}$OH ortho-to-para ratios range between $\sim$0.3-2.3. The volume-averaged CH${3}$OH column densities show a rise with decreasing bolometric luminosity among the proto-BDs, with the median column density higher by a factor of $\sim$3 compared to low-mass protostars. Emission in high-excitation (E${upper}>$ 25 K) CH${3}$OH lines together with the model predictions suggest that a warm corino is present in $\sim$78\% of the proto-BDs in our sample. The remaining show evidence of only the cold component, possibly due to the absence of a strong, high-velocity jet that can stir up the warm gas around it.

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B. Riaz, W. Thi and M. Machida
Wed, 10 May 23
48/65

Comments: Accepted in MNRAS

Discovery of Radial Spectral Hardening in the Hot Bubble of Planetary Nebula BD+30 3639 with Median Energy Imaging [SSA]

http://arxiv.org/abs/2305.04948


We introduce a new imaging analysis technique to study the spatial distribution of the X-ray emission from the hot bubble of planetary nebula BD+30 3639. Hot bubble emission is typically photon-starved, thus limiting the methods for spatial-spectral analysis, however, this new technique uses the statistics of photon energies across the nebula to identify spatial variations. Using the median energy value of the X-ray photons, we identified a rise in median energy values towards the projected edge of the nebula, which we refer to as radial spectral hardening. We explored the origin of this radial spectral hardening with X-ray spectral analysis of distinct regions of high- and low-median energy values. Given that the hot bubble is embedded within a young, dense, planetary nebula, we argue that the radial spectral hardening is due to an increased column density at the projected nebular edge. Median energy imaging provides a promising new methodology for exploring the spatial variations in faint extended X-ray sources.

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R. Jr
Wed, 10 May 23
55/65

Comments: 10 pages, 6 figures, and one potentially embarrassing last minute revision. Submitted to ApJ

Measuring Dust Attenuation Curves of SINGS/KINGFISH Galaxies Using Swift/UVOT Photometry [GA]

http://arxiv.org/abs/2305.05650


We present Swift/Ultraviolet Optical Telescope (UVOT) integrated light photometry of the Spitzer Infrared Nearby Galaxies Survey (SINGS) and the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) samples of nearby galaxies. Combining the Swift/UVOT data with archival photometry, we investigate a variety of dust attenuation curves derived using MCSED, a flexible spectral energy distribution fitting code. We fit the panchromatic data using three different star formation history (SFH) parameterizations: a decaying exponential, a double power law, and a piecewise function with breaks at physically motivated ages. We find that the average attenuation law of the sample changes slightly based on the SFH assumed. Specifically, the exponential SFH leads to the shallowest attenuation curves. Using simulated data, we also find the exponential SFH fails to outperform the more complex SFHs. Finally, we find a systematic offset in the derived bump strength between SED fits with and without UVOT data, where the inclusion of UVOT data leads to smaller bump strengths, highlighting the importance of the UVOT data. This discrepancy is not seen in fits to mock photometry. Understanding dust attenuation in the local universe is key to understanding high redshift objects where rest-frame far-infrared data is unavailable.

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A. Belles, M. Decleir, W. Bowman, et. al.
Wed, 10 May 23
56/65

Comments: 30 pages, 13 figures, accepted for publication in ApJ

More relaxed intracluster gas than galaxies in clusters in quasi-equilibrium [GA]

http://arxiv.org/abs/2305.05250


During cluster mergers, the intracluster gas and member galaxies undergo dynamic evolution, but at different timescales and reach different states. We collect 24 galaxy clusters in quasi-equilibrium state as indicated by the X-ray image, and calculate the cluster orientations and three kinds of dynamical parameters, i.e., the normalized centroid offset, the sphere index and the ellipticity, for these clusters from the distributions of member galaxies and also the intracluster gas. We find consistent alignments for the orientations estimated from the two components. However, the three kinds of dynamical parameters indicated by member galaxies are systematically larger than those derived from the gas component, suggesting that the gas component is more relaxed than member galaxies. Differences of dynamical features between the intracluster gas and member galaxies are independent of cluster mass and concentration. We conclude that the intracluster gas reaches the dynamic equilibrium state earlier than the almost collisionless member galaxies.

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Z. Yuan, J. Han, H. Böhringer, et. al.
Wed, 10 May 23
59/65

Comments: 9 pages, 5 figures, 1 table, accepted for publication in MNRAS

XQR-30: the ultimate XSHOOTER quasar sample at the reionization epoch [GA]

http://arxiv.org/abs/2305.05053


The final phase of the reionization process can be probed by rest-frame UV absorption spectra of quasars at z>6, shedding light on the properties of the diffuse intergalactic medium within the first Gyr of the Universe. The ESO Large Programme “XQR-30: the ultimate XSHOOTER legacy survey of quasars at z~5.8-6.6” dedicated ~250 hours of observations at the VLT to create a homogeneous and high-quality sample of spectra of 30 luminous quasars at z~6, covering the rest wavelength range from the Lyman limit to beyond the MgII emission. Twelve quasar spectra of similar quality from the XSHOOTER archive were added to form the enlarged XQR-30 sample, corresponding to a total of ~350 hours of on-source exposure time. The median effective resolving power of the 42 spectra is R~11400 and 9800 in the VIS and NIR arm, respectively. The signal-to-noise ratio per 10 km/s pixel ranges from ~11 to 114 at $\lambda \simeq 1285$ \AA rest frame, with a median value of ~29. We describe the observations, data reduction and analysis of the spectra, together with some first results based on the E-XQR-30 sample. New photometry in the H and K bands are provided for the XQR-30 quasars, together with composite spectra whose characteristics reflect the large absolute magnitudes of the sample. The composite and the reduced spectra are released to the community through a public repository, and will enable a range of studies addressing outstanding questions regarding the first Gyr of the Universe.

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V. D’Odorico, E. Banados, G. Becker, et. al.
Wed, 10 May 23
60/65

Comments: 21 pages, 10 figures. Revised version resubmitted to MNRAS after minor referee report

An analysis of the isomers HCN and HNC in the evolution of high-mass star-forming regions [GA]

http://arxiv.org/abs/2305.05073


The study of molecules and their chemistry in star-forming regions is fundamental to understand the physical process occurring in such regions. The HCN and HNC J=1-0 emissions were used to derive their integrated line intensities (I), to probe a relation recently appeared in the literature between the kinetic temperatures (T${K}$) and the isomeric (I) ratio, and to obtain the isomers abundances (X) in 55 high-mass star-forming regions. These last ones are classified, according to the evolutive stage, as infrared dark clouds, high-mass protostellar objects, hot molecular cores, and ultracompact HII regions. It is inferred that the T${K}$ obtained from the isomeric integrated intensity ratio (I$^{HCN/HNC}$) are underestimated, and hence we suggest that this relation cannot be employed as an universal thermometer in the interstellar medium. The isomers abundances show a behavior that can be explained from the chemistry occurring as the temperature and the UV radiation increase according to the evolutive stage. We found that the abundance ratio (X$^{HCN/HNC}$) hardly could be used as a chemical clock, and we suggest that it can be approximated by I$^{HCN/HNC}$. This work is part of an on-going study of multiple molecules that stand in the sample of analyzed regions which intends to contribute in the chemical knowledge of high-mass star formation.

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N. Martinez and S. Paron
Wed, 10 May 23
62/65

Comments: to appear in Bolet\’in de la Asociaci\’on Argentina de Astronom\’ia

Revisiting the Dragonfly Galaxy I. High-resolution ALMA and VLA Observations of the Radio Hotspots in a Hyper-luminous Infrared Galaxy at $z=1.92$ [GA]

http://arxiv.org/abs/2305.03979


Radio-loud active galactic nuclei (RLAGNs) are rare among AGN populations. Lacking high-resolution and high-frequency observations, their structure and evolution stages are not well understood at high redshifts. In this work, we report ALMA 237 GHz continuum observation at $0.023”$ resolution and VLA 44 GHz continuum observation at $0.08”$ resolution of the radio continuum emission from a high-redshift radio and hyper-luminous infrared galaxy at $z=1.92$. The new observations confirm the South-East (SE) and North-West (NW) hotspots identified by previous low-resolution VLA observations at 4.7 and 8.2 GHz and identify a radio core undetected in all previous observations. The SE hotspot has a higher flux density than the NW one does by a factor of 6, suggesting that there can be a Doppler boosting effect in the SE one. In this scenario, we estimate the advance speed of the jet head, ranging from $\sim$0.1c — 0.3c, which yields a mildly relativistic case. The projected linear distance between the two hotspots is $\sim13$ kpc, yielding a linear size ($\leq20$ kpc) of a Compact-Steep-Spectrum (CSS) source. Combined with new \black{high-frequency ($\nu_\text{obs}\geq44$ GHz) and archived low-frequency observations ($\nu_\text{obs}\leq8.2$ GHz)}, we find that injection spectra of both NW and SE hotspots can be fitted with a continuous injection (CI) model. Based on the CI model, the synchrotron ages of NW and SE hotspots have an order of $10^5$ yr, consistent with the order of magnitude $10^3 – 10^5$ yr observed in CSS sources associated with radio AGNs at an early evolution stage. The CI model also favors the scenario in which the double hotspots have experienced a quiescent phase, suggesting that this RLAGN may have transient or intermittent activities.

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Y. Zhong, A. Inoue, Y. Sugahara, et. al.
Tue, 9 May 23
2/88

Comments: Accepted for publication in MNRAS

Diverse Chemo-Dynamical Properties of Nitrogen-Rich Stars Identified From Low-Resolution Spectra [GA]

http://arxiv.org/abs/2305.04025


The second generation of stars in the GCs of the MW exhibit unusually high N, Na, or Al, compared to typical Galactic halo stars at similar metallicities. The halo field stars enhanced with such elements are believed to have originated in disrupted GCs or escaped from existing GCs. We identify such stars in the metallicity range -3.0 < [Fe/H] < 0.0 from a sample of ~ 36,800 giant stars observed in the SDSS and LAMOST survey, and present their dynamical properties. The N-rich population and N-normal population among our giant sample do not exhibit similarities in either in their metallicity distribution function or dynamical properties. We find that, even though the MDF of the NRP looks similar to that of the MW’s GCs in the range of [Fe/H] < -1.0, our analysis of the dynamical properties does not indicate similarities between them in the same metallicity range, implying that the escaped members from existing GCs may account for a small fraction of our N-rich stars, or the orbits of the present GCs have been altered by the dynamical friction of the MW. We also find a significant increase in the fraction of N-rich stars in the halo field in the very metal-poor (VMP; [Fe/H] < -2.0) regime, comprising up to ~ 20% of the fraction of the N-rich stars below [Fe/H] = -2.5, hinting that partially or fully destroyed VMP GCs may have in some degree contributed to the Galactic halo. A more detailed dynamical analysis of the NRP reveals that our sample of N-rich stars do not share a single common origin. Although a substantial fraction of the N-rich stars seem to originate from the GCs formed in situ, more than 60% of them are not associated with those of typical Galactic populations, but probably have extragalactic origins associated with GSE, Sequoia, and Sagittarius dwarf galaxies, as well as with presently unrecognized progenitors.

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C. Kim, Y. Lee, T. Beers, et. al.
Tue, 9 May 23
5/88

Comments: 16 pages, 6 figures, 1 table

Faint Galaxy Number Counts in the Durhamand SDSS Catalogues [GA]

http://arxiv.org/abs/2305.04308


Galaxy number counts in the $K$-, $H$-, $I$-, $R$-, $B$- and $U$-bands from the Durham Extragalactic Astronomy and Cosmology catalogue could be well-fitted over their whole range using luminosity function (LF) parameters derived from the SDSS at the bright region and required only modest luminosity evolution with the steepening of the LF slope ($\alpha$), except for a sudden steep increase in the $B$-band and a less steep increase in the $U$-band at faint magnitudes that required a starburst evolutionary model to account for the excess faint number counts. A cosmological model treating Hubble expansion as an Einstein curvature required less correction at faint magnitudes than a standard $\Lambda$CDM model, without requiring dark matter or dark energy. Data from DR17 of the SDSS in the $g$, $i$, $r$, $u$ and $z$ bands over two areas of the sky centred on the North Galactic Cap (NGC) and above the South Galactic Cap (SGC), with areas of 5954 and 859 sq. deg., respectively, and a combined count of 622,121 galaxies, were used to construct bright galaxy number counts and galaxy redshift/density plots within the limits of redshift $\leq0.4$ and mag $\leq20$. Their comparative densities confirmed an extensive void in the Southern sky with a deficit of 26\% out to a redshift $z$$\leq$0.15. Although not included in the number count data set because of its incompleteness at fainter magnitudes, extending the SDSS redshift-number count survey to fainter and more distant galaxies with redshift $\leq1.20$ showed a secondary peak in the number counts with many QSOs, bright X-ray and radio sources, and evolving irregular galaxies with rapid star formation rates. This sub-population at redshifts of 0.45–0.65 may account for the excess counts observed in the $B$-band.

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J. Marr
Tue, 9 May 23
7/88

Comments: 19 pages, 10 figures

No Surviving SN Ia Companion In SNR 0509-67.5: Stellar Population Characterization and Comparison To Models [SSA]

http://arxiv.org/abs/2305.03750


The community agrees that Type Ia supernovae arise from Carbon/Oxygen white dwarfs undergoing thermonuclear runaway. However, the full progenitor system and the process that prompts the white dwarf to explode remain unknown. Most current models suggest that the white dwarf explodes because of interaction with a binary companion which may survive the process and remain within the resulting remnant of the exploded star. Furthermore, both the pre-supernova interaction process and the explosion of the primary are expected to imprint a significant departure from ordinary stellar radii and temperatures onto the secondary, making the star identifiable against the unrelated stellar population. Identification of a surviving companion inside an SN Ia remnant might confirm a specific corresponding SN Ia progenitor channel based on the identity of the companion. We conducted a surviving companion search of the Type Ia remnant SNR 0509-67.5 based in the Large Magellanic Cloud. The well-constrained distance to and foreground extinction of the Large Magellanic Cloud allow for Bayesian inference of stellar parameters with low correlation and uncertainties. We present a deep catalog of fully characterized stars interior to SNR 0509-67.5 with radii, effective temperatures, and metallicities inferred using combined Hubble Space Telescope photometric observations across multiple visits. We then compile a list of surviving companion models appropriate for the age of the remnant (roughly 400 years after the explosion). We compare these predictions with the inferred stellar parameters and conclude that none of the stars are consistent with the predicted signatures of a surviving companion.

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J. Shields, P. Arunachalam, W. Kerzendorf, et. al.
Tue, 9 May 23
8/88

Comments: 16 pages, 8 figures, 4 tables

Vivisecting galaxies with BANG: an automated morpho-kinematical decomposition of the SDSS-DR17 MaNGA survey [GA]

http://arxiv.org/abs/2305.03762


From a purely photometric perspective galaxies are generally decomposed into a bulge+disc system, with bulges being dispersion-dominated and discs rotationally-supported. However, recent observations have demonstrated that such framework oversimplifies complexity, especially if one considers galaxy kinematic.To address this issue we introduced with the GPU-based code \textsc{bang} a novel approach that employs analytical potential-density pairs as galactic components, allowing for a computationally fast, still reliable fit of the morphological and kinematical properties of galaxies. Here we apply \textsc{bang} to the SDSS-MaNGA survey, estimating key parameters such as mass, radial extensions, dynamics, for both bulges and discs of +10,000 objects. We test our methodology against a smaller subsample of galaxies independently analysed with an orbit-based algorithm, finding agreement in the recovered total stellar mass. We also manage to reproduce well-established scaling relations, demonstrating how a proper dynamical modelling can result in tighter correlations and provide corrections to standard approaches. Finally, we propose a more general way of decomposing galaxies into “hot” and “cold” components, showing a correlation with orbit-based approaches and visually determined morphological type. Unexpected tails in the “hot-to-total” mass-ratio distribution are present for galaxies of all morphologies, possibly due to visual morphology misclassifications.

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F. Rigamonti, M. Dotti, S. Covino, et. al.
Tue, 9 May 23
9/88

Comments: 13 pages, 10 figures

Exploring the environment, magnetic fields, and feedback effects of massive high-redshift galaxies with [CII] [GA]

http://arxiv.org/abs/2305.03812


Massive galaxies are expected to grow through different transformative evolutionary phases where high-redshift starburst galaxies and quasars are examples of such phases. The physical mechanisms driving these phases include companion galaxy interactions, active galactic nuclei feedback, and magnetic fields. Our aim is to characterize the physical properties and the environment of the submillimeter galaxy AzTEC-3 at z = 5.3 and the lensed quasar BRI 0952-0115 at z = 4.4, to set a limit on the polarization properties, as well as placing both in the broader context of galaxy evolution. We used full polarization, sub-arcsecond-resolution, ALMA band-7 observations of both BRI 0952-0115 and AzTEC-3 and detect [CII] line emission towards both galaxies, along with companions in each field. We present an updated gravitational lensing model for BRI 0952-0115. We present infrared luminosities, star-formation rates, and [CII] line to infrared luminosity ratios for each source. The [CII] emission line profile for both BRI 0952-0115 and AzTEC-3 exhibit a broad, complex morphology, indicating the possible presence of outflows. We present evidence of a ‘gas bridge’ between AzTEC-3 and a companion source. Using a simple dynamical mass estimate for the sources, we suggest that both systems are undergoing minor or major mergers. No polarization is detected for the [CII], placing an upper limit below that of theoretical predictions. Our results show that high-velocity wings are detected, indicating possible signs of massive outflows; however, the presence of companion galaxies can affect the final interpretation. Furthermore, the results provide additional evidence in support of the hypothesis that massive galaxies form in overdense regions, growing through interactions. Finally, strong, ordered magnetic fields are unlikely to exist at the kiloparsec scale in the two studied sources.

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K. Kade, K. Knudsen, W. Vlemmings, et. al.
Tue, 9 May 23
10/88

Comments: N/A

Evolution of radioactive elements in the LMC: predictions for future gamma-ray surveys [GA]

http://arxiv.org/abs/2305.04753


Short-lived radionuclides, such as 26Al and 60Fe, are tracers of star formation. Therefore, their abundances can unravel the recent star formation history of the host galaxy. In view of future gamma-ray surveys, we predict the masses and fluxes of these two elements in the Large Magellanic Cloud (LMC) using new chemical evolution models. Our best model reproduces the abundance patterns of alpha/Fe ratios, the gas mass, the average metallicity, the present time supernova and nova rates observed in LMC. We show three main results: i) the best model for the LMC suggests a star formation rate very mild at the beginning with a recent burst, and a Salpeter-like initial mass function. ii) The predicted mass of 26Al is 0.33 M_Sun, 2/3 produced by massive stars and 1/3 by novae. iii) The predicted mass of 60Fe is 0.44 M_Sun, entirely produced by massive stars. This result suggests a larger fraction of 60Fe, at variance with the Milky Way. The explanation for this lies in the adopted initial mass function, that for the LMC contains more massive stars than for the Milky Way. These predictions can be useful for the COSI-SMEX mission planned for launch in 2027. The expected gamma-ray line fluxes for the 1.809 MeV line of 26Al and the 1.173 and 1.332 MeV lines of 60Fe are in the range of (0.2-2.7)x10^-6 ph cm^-2 s^-1 and (0.7-2.8)x10^-7 ph cm^-2 s^-1, respectively. This new instrument could have the sensitivity to detect the upper end of the predicted 1.8 MeV flux within its nominal two-year mission.

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A. Vasini, F. Matteucci, E. Spitoni, et. al.
Tue, 9 May 23
13/88

Comments: 11 pages, 2 figures, 4 tables, accepted for publication by MNRAS

Neutral outflows in high-z QSOs [GA]

http://arxiv.org/abs/2305.04098


OH+ absorption is a powerful tracer of inflowing and outflowing gas in the predominantly atomic diffuse and turbulent halo surrounding galaxies. In this letter, we present observations of OH+(1_1-1_0), CO(9-8) and the underlying dust continuum in 5 strongly lensed z~2-4 QSOs, using ALMA to detect outflowing neutral gas. Blue-shifted OH+ absorption is detected in 3/5 QSOs and tentatively detected in a 4th. Absorption at systemic velocities is also detected in one. OH+ emission is observed in 3/5 QSOs at systemic velocities and CO(9-8) is detected in all 5 QSOs at high S/N, providing information on the dense molecular gas within the host galaxy. We compare our sample to high-z far-infrared (FIR) luminous star-forming and active galaxies from the literature. We find no difference in OH+ absorption line properties between active and star-forming galaxies with both samples following the same optical depth-dust temperature relation, suggesting that these observables are driven by the same mechanism in both samples. Similarly, star-forming and active galaxies both follow the same OH+ emission-FIR relation. Obscured QSOs display broader (>800 km/s) emission than the unobscured QSOs and all but one of the high-z star-forming galaxies, likely caused by the warm molecular gas reservoir obscuring the accreting nucleus. Broader CO(9-8) emission (>500 km/s) is found in obscured versus unobscured QSOs, but overall cover a similar range in line widths as the star-forming galaxies and follow the CO(9-8)-FIR luminosity relation found in low-z galaxies. We find that outflows traced by OH+ are only detected in extreme star-forming galaxies (broad CO emission) and in both types of QSOs, which, in turn, display no red-shifted absorption. This suggests that diffuse neutral outflows in galaxy halos may be associated with the most energetic evolutionary phases leading up to and following the obscured QSO phase.

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K. Butler, P. Werf, A. Omont, et. al.
Tue, 9 May 23
15/88

Comments: 8 pages, 3 figures, 4 tables, accepted to A&A letters

Investigating Loop Quantum Gravity Through Strong Gravitational Lensing Effects by Rotating Black Hole and EHT Observations [CL]

http://arxiv.org/abs/2305.04336


We investigate gravitational lensing in the strong deflection regime by loop quantum gravity (LQG)-motivated rotating black hole (LMRBH) metrics with an additional parameter $l$ besides mass $M$ and rotation $a$. The LMRBH spacetimes are regular everywhere, asymptotically encompassing the Kerr black hole as a particular case and, depending on the parameters, describe black holes with one horizon only (BH-I), black holes with an event horizon and a Cauchy horizon (BH-II), black holes with three horizons (BH-III), or black holes with no horizons (NH) spacetime. It turns out that as the LQG parameter $l$ increases, the unstable photon orbit radius $x_{ps}$, the critical impact parameter $u_{ps}$, the deflection angle $\alpha_D(\theta)$ and angular position $\theta_{\infty}$ also increases. Meanwhile, the angular separation $s$ decreases, and relative magnitude $r_{mag}$ increases with increasing $l$ for prograde motion but they show opposite behaviour for the retrograde motion. For Sgr A*, the angular position $\theta_{\infty}$ is $\in$ (16.404, 39.8044) $\mu$as, while for M87* $\in$ (12.3246, 29.9057) $\mu$as. The angular separation $s$ is ranging $\in$ (0.008306-0.37573) $\mu$as for Sgr A* and $\in$ (0.00624-0.282295) $\mu$as for M87*. The relative magnitude $r_{mag}$ $\in$ (0.04724, 1.53831). We estimate the time delay between the first and second relativistic images using twenty supermassive galactic centre black holes as lenses. Our analysis concludes that, within the $1 \sigma$ region, a significant portion of the BH-I and BH-II and for a small portion of BH-III parameter space agrees with the EHT results of M87* and Sgr A* whereas NH is completely ruled out. We discover that the EHT results of Sgr A* place more stringent limits on the parameter space of LMRBH black holes than those established by the EHT results of M87*.

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J. Kumar, S. Islam and S. Ghosh
Tue, 9 May 23
16/88

Comments: 15 pages, 10 figures, 3 tables

Non-thermal emissions from a head-tail radio galaxy in 3D magnetohydrodynamic simulations [HEAP]

http://arxiv.org/abs/2305.04795


We present magnetohydrodynamic simulations of a jet-wind interaction in a galaxy cluster and the radio to gamma-ray and the neutrino emissions from this “head-tail galaxy”. Our simulation follows the evolution of cosmic-ray (CR) particle spectra with energy losses and the stochastic turbulence acceleration. We find that the reacceleration is essential to explain the observed radio properties of head-tail galaxies, in which the radio flux and spectral index do not drastically change. Our models suggest that hard X-ray emissions can be detected around the head-tail galaxy in the Perseus cluster by the hard X-ray satellites, such as FORCE, and it will potentially constrain the acceleration efficiency. We also explore the origin of the collimated synchrotron threads, which are found in some head-tail galaxies by recent high-quality radio observations. Thin and elongated flux tubes, connecting the two tails, are formed by strong backflows at an early phase. We find that these threads advect with the wind for over 300 Myr without disrupting. The radio flux from the flux tubes is much lower than the typical observed flux. An efficient CR diffusion process along the flux tubes, however, may solve this discrepancy.

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T. Ohmura, K. Asano, K. Nishiwaki, et. al.
Tue, 9 May 23
17/88

Comments: 16 pages, 10 figures, accepted for publication in ApJ

SDSS-IV MaNGA: The Incidence of Major Mergers in type I and II AGN Host Galaxies in the DR15 sample [GA]

http://arxiv.org/abs/2305.03834


We present a study on the incidence of major mergers and their impact on the triggering of nuclear activity in 47 type I and 236 type II optically-selected AGN from the MaNGA DR15 sample. From an estimate of non-parametric image predictors ($Gini$, M$_{20}$, concentration (C), asymmetry (A), clumpiness (S), S\’ersic index (n), and shape asymmetry($A_S$)) using the SDSS images, in combination with a Linear Discriminant Analysis Method, we identified major mergers and merger stages. We reinforced our results by looking for bright tidal features in our post-processed SDSS and DESI legacy images. We find a statistically significant higher incidence of major mergers of 29\% $\pm$ 3\% in our type I+II AGN sample compared to 22\% $\pm$ 0.8\% for a non-AGN sample matched in redshift, stellar mass, color and morphological type, finding also a prevalence of post-coalescence (51\% $\pm$ 5\%) over pre-coalescence (23\% $\pm$ 6\%) merger stages. The levels of AGN activity among our massive major mergers are similar to those reported in other works using \oiii\ tracers. However, similar levels are produced by our AGN-galaxies hosting stellar bars, suggesting that major mergers are important promoters of nuclear activity but are not the main nor the only mechanism behind the AGN triggering. The tidal strength parameter $Q$ was considered at various scales looking for environmental differences that could affect our results on the merger incidence, finding non-significant differences. Finally, the H-H$\beta$ diagram could be used as an empirical predictor for the flux coming from an AGN source, useful to correct photometric quantities in large AGN samples emerging from surveys.

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H. Hernández-Toledo, E. Cortes-Suárez, J. Vázquez-Mata, et. al.
Tue, 9 May 23
19/88

Comments: 23 pages, 13 figures, 10 tables

Does the i-process operate at nearly solar metallicity? [SSA]

http://arxiv.org/abs/2305.04189


A sample of 895 s-process-rich candidates has been found among the 454180 giant stars surveyed by LAMOST at low spectral resolution (R~1800). In a previous study, taking advantage of the higher resolution (R~86 000) offered by the the HERMES-Mercator spectrograph, we performed the re-analysis of 15 among the brightest stars of this sample. Among these 15 program stars, having close-to-solar metallicities, 11 showed mild to strong heavy element overabundances. The nucleosynthesis process(es) at the origin of these overabundances were however not questioned in our former study. We derive the abundances in s- and r-process elements of the 15 targets in order to investigate whether some stars also show an i-process signature, as sometimes found in their lower metallicity counterparts (namely, the Carbon-Enhanced Metal-Poor (CEMP)-rs stars). Abundances are derived from the high-resolution HERMES spectra for Pr, Nd, Sm, and Eu, using the TURBOSPECTRUM radiative transfer LTE code with MARCS model atmospheres. Using the new classification scheme proposed in our recent study we find that two stars show overabundances in both s- and r-process elements well above the level expected from the Galactic chemical evolution, an analogous situation to the one of CEMP-rs stars at lower metallicities. We compare the abundances of the most enriched stars with the nucleosynthetic predictions from the STAREVOL stellar evolutionary code and find abundances compatible with an i-process occurring in AGB stars. Despite a larger number of heavy elements to characterize the enrichment pattern, the limit between CEMP-s and CEMP-rs stars remains fuzzy. It is however interesting to note that an increasing number of extrinsic stars are found to have abundances better reproduced by an i-process pattern even at close-to-solar metallicities.

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D. Karinkuzhi, S. Eck, S. Goriely, et. al.
Tue, 9 May 23
20/88

Comments: Accepted for publication in A&A, 9 pages, 9 figures including the two in appendix