First constraints of dense molecular gas at z~7.5 from the quasar Pōniuā'ena [GA]

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http://arxiv.org/abs/2304.09129


We report the detection of CO(6-5) and CO(7-6) and their underlying continua from the host galaxy of quasar J100758.264+211529.207 (P\=oniu\=a’ena) at z=7.5419, obtained with the NOrthern Extended Millimeter Array (NOEMA). P\=oniu\=a’ena belongs to the HYPerluminous quasars at the Epoch of ReionizatION (HYPERION) sample of 17 $z>6$ quasars selected to be powered by supermassive black holes (SMBH) which experienced the fastest mass growth in the first Gyr of the Universe. The one reported here is the highest-redshift measurement of the cold and dense molecular gas to date. The host galaxy is unresolved and the line luminosity implies a molecular reservoir of $\rm M(H_2)=(2.2\pm0.2)\times 10^{10}$ $\rm M_\odot$, assuming a CO spectral line energy distribution typical of high-redshift quasars and a conversion factor $\alpha=0.8$ $\rm M_{\odot} (K\,km \, s^{-1} \,pc^{2})^{-1} $. We model the cold dust spectral energy distribution (SED) to derive a dust mass of M${\rm dust} =(2.1\pm 0.7)\times 10^8$ $\rm M\odot$, and thus a gas to dust ratio $\sim100$. Both the gas and dust mass are not dissimilar from the reservoir found for luminous quasars at $z\sim6$. We use the CO detection to derive an estimate of the cosmic mass density of $\rm H_2$, $\Omega_{H_2} \simeq 1.31 \times 10^{-5}$. This value is in line with the general trend suggested by literature estimates at $ z < 7 $ and agrees fairly well with the latest theoretical expectations of non-equilibrium molecular-chemistry cosmological simulations of cold gas at early times.

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C. Feruglio, U. Maio, R. Tripodi, et. al.
Wed, 19 Apr 23
20/58

Comments: Submitted to ApJ Letters

X-ray flashes from the low-mass X-ray binary IGR J17407-2808 [HEAP]

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http://arxiv.org/abs/2304.08816


IGR J17407-2808 is an enigmatic and poorly studied X-ray binary that was recently observed quasi-simultaneously with NuSTAR and XMM-Newton. In this paper we report the results of this observational campaign. During the first 60 ks of observation, the source was caught in a relatively low emission state, characterised by a modest variability and an average flux of ~8.3E-13 erg/cm^2/s (4-60 keV). Afterwards, IGR J17407-2808 entered a significantly more active emission state that persisted for the remaining ~40 ks of the NuSTAR observation. During this state, IGR J17407-2808 displayed several fast X-ray flares, featuring durations of ~1-100 s and profiles with either single or multiple peaks. The source flux in the flaring state reached values as high as 2E-9 erg/cm^2/s (4-60 keV), leading to a measured dynamic range during the NuSTAR and XMM-Newton campaign of >~ 10^3. We also analysed available archival photometric near-infrared data of IGR J17407-2808 to improve the constraints available so far on the the nature of the donor star hosted in this system. Our analysis shows that the donor star can be either a rare K or M-type sub-subgiant or an K type main sequence star, or sub-giant star. Our findings support the classification of IGR J17407-2808 as a low-mass X-ray binary. We discuss the source X-ray behaviour as recorded by NuSTAR and XMM-Newton in view of this revised classification.

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L. Ducci, C. Malacaria, P. Romano, et. al.
Wed, 19 Apr 23
21/58

Comments: Accepted for publication in Astronomy & Astrophysics

Current and Future constraints on Very-Light Axion-Like Particles from X-ray observations of cluster-hosted Active Galaxies [HEAP]

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http://arxiv.org/abs/2304.08513


We discuss our recent constraints on the coupling of Very-Light Axion-Like Particles (of masses $<$$ 10^{-12} \ \mathrm{eV}$) to electromagnetism from $Chandra$ observations of the cluster-hosted Active Galactic Nuclei (AGN) H1821+643 and NGC1275. In both cases, the inferred high-quality AGN spectra excluded all photon-ALP couplings $g_\mathrm{a\gamma} > (6.3 – 8.0) \times 10^{-13} \ {\mathrm{GeV}}^{-1}$ at the $99.7\%$ level, respectively, based on the non-detection of spectral distortions attributed to photon-ALP inter-conversion along the cluster line-of-sight. Finally, we present the prospects of tightening current bounds on such ALPs by up to a factor of 10 with next-generation X-ray observatories such as $Athena$, $AXIS$ and $LEM$ given their improved spectral and spatial resolution and collecting area compared to current missions.

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J. Sisk-Reynes, C. Reynolds and J. Matthews
Wed, 19 Apr 23
22/58

Comments: 4 pages, 1 figure. Accepted for publication to Memorie della SAIt for the Proceedings of the European Astronomical Society 2022 (EAS 2022) Annual Meeting Symposium S3 “The Dark matter multi-messenger challenge”

Cosmology with Galaxy Cluster Properties using Machine Learning [CEA]

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http://arxiv.org/abs/2304.09142


[Abridged] Galaxy clusters are the most massive gravitationally-bound systems in the universe and are widely considered to be an effective cosmological probe. We propose the first Machine Learning method using galaxy cluster properties to derive unbiased constraints on a set of cosmological parameters, including Omega_m, sigma_8, Omega_b, and h_0. We train the machine learning model with mock catalogs including “measured” quantities from Magneticum multi-cosmology hydrodynamical simulations, like gas mass, gas bolometric luminosity, gas temperature, stellar mass, cluster radius, total mass, velocity dispersion, and redshift, and correctly predict all parameters with uncertainties of the order of ~14% for Omega_m, ~8% for sigma_8, ~6% for Omega_b, and ~3% for h_0. This first test is exceptionally promising, as it shows that machine learning can efficiently map the correlations in the multi-dimensional space of the observed quantities to the cosmological parameter space and narrow down the probability that a given sample belongs to a given cosmological parameter combination. In the future, these ML tools can be applied to cluster samples with multi-wavelength observations from surveys like CSST in the optical band, Euclid and Roman in the near-infrared band, and eROSITA in the X-ray band to constrain both the cosmology and the effect of the baryonic feedback.

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L. Qiu, N. Napolitano, S. Borgani, et. al.
Wed, 19 Apr 23
23/58

Comments: 18 pages, submitted to A&A Main Journal. Comments are welcome

Ultra-high-resolution Observations of Persistent Null-point Reconnection in the Solar Corona [SSA]

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http://arxiv.org/abs/2304.08725


Magnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, we present ultra-high-resolution extreme ultraviolet observations of persistent null-point reconnection in the corona at a scale of about 390 km over one hour observations of the Extreme-Ultraviolet Imager on board Solar Orbiter spacecraft. The observations show formation of a null-point configuration above a minor positive polarity embedded within a region of dominant negative polarity near a sunspot. The gentle phase of the persistent null-point reconnection is evidenced by sustained point-like high-temperature plasma (about 10 MK) near the null-point and constant outflow blobs not only along the outer spine but also along the fan surface. The blobs appear at a higher frequency than previously observed with an average velocity of about 80 km/s and life-times of about 40 s. The null-point reconnection also occurs explosively but only for 4 minutes, its coupling with a mini-filament eruption generates a spiral jet. These results suggest that magnetic reconnection, at previously unresolved scales, proceeds continually in a gentle and/or explosive way to persistently transfer mass and energy to the overlying corona.

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X. Cheng, E. Priest, H. Li, et. al.
Wed, 19 Apr 23
24/58

Comments: 27 pages, 7 figures

Exorcising the Ghost Condensate Dark Energy with a Sextic Dispersion Relation [CL]

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http://arxiv.org/abs/2304.07344


The universe’s current acceleration is a pretty recent phenomenon in cosmological time scales. This means that the modes that have left our horizon since the beginning of the contemporary acceleration phase, have not really reached the exact IR limit. Noting this observation, we reconsider the possibility of having a ghost condensate as dark energy with a sixth-order dispersion relation. Looking at the three-point function of such a theory, we obtain the constraints on the coefficient of the sixth-order dispersion relation to avoid strong coupling. Such a ghost condensate if coupled to the standard model fields, induces a constant Lorentz-violating spin-dependent force, which can gravitate or anti-gravitate.

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A. Ashoorioon and A. Yousefi-Sostani
Wed, 19 Apr 23
25/58

Comments: 15+1 pages

Effective description of generalized disformal theories [CL]

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http://arxiv.org/abs/2304.08624


Generalized disformal transformations enable us to construct the generalized disformal Horndeski theories, which form the most general class of ghost-free scalar-tensor theories to this date. We extend the effective field theory (EFT) of cosmological perturbations to incorporate these generalized disformal Horndeski theories. The main difference from the conventional EFT is that our extended EFT involves operators with higher spatial derivatives of the lapse function. Our EFT also accommodates the generalized disformal transformation of U-DHOST theories.

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K. Takahashi, M. Minamitsuji and H. Motohashi
Wed, 19 Apr 23
26/58

Comments: 14 pages

The progenitors of Type Ia supernovae with asymptotic giant branch donors [SSA]

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http://arxiv.org/abs/2304.08839


Type Ia supernovae (SNe Ia) are among the most energetic events in the Universe. They are excellent cosmological distance indicators due to the remarkable homogeneity of their light curves. However, the nature of the progenitors of SNe Ia is still not well understood. In the single-degenerate model, a carbon-oxygen white dwarf (CO WD) could grow its mass by accreting material from an asymptotic giant branch (AGB) star, leading to the formation of SNe Ia when the mass of the WD approaches to the Chandrasekhar-mass limit, known as the AGB donor channel. In this channel, previous studies mainly concentrate on the wind-accretion pathway for the mass-increase of the WDs. In the present work, we employed an integrated mass-transfer prescription for the semidetached WD+AGB systems, and evolved a number of WD+AGB systems for the formation of SNe Ia through the Roche-lobe overflow process or the wind-accretion process. We provided the initial and final parameter spaces of WD+AGB systems for producing SNe Ia. We also obtained the density distribution of circumstellar matter at the moment when the WD mass reaches the Chandrasekhar-mass limit. Moreover, we found that the massive WD+AGB sample AT 2019qyl can be covered by the final parameter space for producing SNe Ia, indicating that AT 2019qyl is a strong progenitor candidate of SNe Ia with AGB donors.

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L. Li, D. Liu and B. Wang
Wed, 19 Apr 23
27/58

Comments: 12 pages, 5 figures, accepted for publication in Res. Astron. Astrophys

Bayesian averaging for ground state masses of atomic nuclei in a Machine Learning approach [CL]

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http://arxiv.org/abs/2304.08546


We present global predictions of the ground state mass of atomic nuclei based on a novel Machine Learning (ML) algorithm. We combine precision nuclear experimental measurements together with theoretical predictions of unmeasured nuclei. This hybrid data set is used to train a probabilistic neural network. In addition to training on this data, a physics-based loss function is employed to help refine the solutions. The resultant Bayesian averaged predictions have excellent performance compared to the testing set and come with well-quantified uncertainties which are critical for contemporary scientific applications. We assess extrapolations of the model’s predictions and estimate the growth of uncertainties in the region far from measurements.

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M. Mumpower, M. Li, T. Sprouse, et. al.
Wed, 19 Apr 23
28/58

Comments: 15 pages, 10 figures, comments welcome

An ultrafast outflow in the black hole candidate MAXI J1810-222? [HEAP]

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http://arxiv.org/abs/2304.08514


The transient X-ray source MAXI J1810-222 was discovered in 2018 and has been active ever since. A long combined radio and X-ray monitoring campaign was performed with ATCA and Swift respectively. It has been proposed that MAXI J1810-222 is a relatively distant black hole X-ray binary, albeit showing a very peculiar outburst behaviour. Here, we report on the spectral study of this source making use of a large sample of NICER observations performed between 2019 February and 2020 September. We detected a strong spectral absorption feature at $\sim$1 keV, which we have characterised with a physical photoionisation model. Via a deep scan of the parameters space, we obtained evidence for a spectral-state dependent outflow, with mildly relativistic speeds. In particular, the soft and intermediate states point to a hot plasma outflowing at 0.05-0.15 $c$. This speeds rule-out thermal winds and, hence, they suggest that such outflows could be radiation pressure or (most likely) magnetically-driven winds. Our results are crucial to test current theoretical models of wind formation in X-ray binaries.

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M. Santo, C. Pinto, A. Marino, et. al.
Wed, 19 Apr 23
29/58

Comments: 6 pages, 10 figures, accepted for publication in MNRAS Letter

Evolution of matter and galaxy clustering in cosmological hydrodynamical simulations [CEA]

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http://arxiv.org/abs/2304.09035


We quantify the evolution of matter and galaxy clustering in cosmological hydrodynamical simulations via correlation and bias functions of matter and galaxies. We use simulations TNG100 and TNG300 with epochs from $z=5$ to $z=0$. We calculate spatial correlation functions of galaxies, $\xi(r)$, for simulated galaxies and dark matter (DM) particles to characterise the evolving cosmic web. We find that bias parameters decrease during the evolution, confirming earlier results. At low and medium luminosities, bias parameters of galaxies, $b_0$, are equal, suggesting that dwarf galaxies reside in the same filamentary web as brighter galaxies. Bias parameters of the lowest luminosity galaxies estimated from CFs are lower relative to CFs of particle density-limited clustered samples of DM. We find that bias parameters $b_0$, estimated from CFs of clustered DM, agree with the expected values from the fraction of particles in the clustered population, $b=1/F_c$. The cosmic web contains filamentary structures of various densities, and fractions of matter in the clustered and the unclustered populations are both less than unity. Thus the CF amplitude of the clustered matter is always higher than for all matter, i.e. bias parameter must be $b>1$. Differences between CFs of galaxies and clustered DM suggest that these functions describe different properties of the cosmic web.

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J. Einasto, G. Hütsi, L. Liivamägi, et. al.
Wed, 19 Apr 23
30/58

Comments: 15 pages, 10 figures, submitted to Monthly Notices of Royal Astronomical Society

Mass measurements and 3D orbital geometry of PSR J1933$-$6211 [HEAP]

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http://arxiv.org/abs/2304.09060


PSR J1933$-$6211 is a 3.5-ms pulsar in a 12.8-d orbit with a white dwarf (WD). Its high proper motion and low dispersion measure result in such significant interstellar scintillation that high signal-to-noise detections require long observing durations or fortuitous timing. We turn to the sensitive MeerKAT telescope and, combined with historic Parkes data, leverage PSR J1933$-$6211’s kinematic and relativistic effects to constrain its 3D orbital geometry and the component masses. We obtain precise proper motion and parallax estimates, and measure their effects as secular changes in the Keplerian orbital parameters: a variation in orbital period of $7(1) \times 10^{-13}$ s s$^{-1}$ and a change in projected semi-major axis of $1.60(5) \times 10^{-14}$ s s$^{-1}$. A self-consistent analysis of all kinematic and relativistic effects yields a distance of $1.6^{+0.2}{-0.3}$ kpc, an orbital inclination, $i = 55(1)$ deg and a longitude of the ascending node, $\Omega = 255^{+8}{-14}$ deg. The probability densities for $\Omega$ and $i$ and their symmetric counterparts, ($180-i$, $360-\Omega$), are seen to depend on the fiducial orbit used to measure the time of periastron passage. We investigate this unexpected dependence and rule out software-related causes using simulations. Nevertheless, we constrain the pulsar and WD masses to $1.4^{+0.3}{-0.2}$ M$\odot$ and $0.43(5)$ M$\odot$ respectively. These strongly disfavour a helium-dominated WD. The orbital similarities between PSRs J1933$-$6211 and J1614$-$2230 suggest they underwent Case A Roche lobe overflow, an extended evolution while the companion star is still on the Main Sequence. However, with a mass of $\sim 1.4$ M$\odot$, PSR J1933$-$6211 has not accreted significant matter. This highlights the low accretion efficiency of the spin-up process and suggests that observed neutron star masses are mostly a result of supernova physics.

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M. Geyer, V. Krishnan, P. Freire, et. al.
Wed, 19 Apr 23
31/58

Comments: 16 pages, 7 figures. Abstract shortened to adhere to ArXiv limit

The Panchromatic Hubble Andromeda Treasury XX: The Disk of M31 is Thick [GA]

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http://arxiv.org/abs/2304.08613


We present a new approach to measuring the thickness of a partially face-on stellar disk, using dust geometry. In a moderately-inclined disk galaxy, the fraction of reddened stars is expected to be 50% everywhere, assuming that dust lies in a thin midplane. In a thickened disk, however, a wide range of radii project onto the line of sight. Assuming stellar density declines with radius, this geometrical projection leads to differences in the numbers of stars on the near and far sides of the thin dust layer. The fraction of reddened stars will thus differ from the 50% prediction, with a deviation that becomes larger for puffier disks. We map the fraction of reddened red giant branch (RGB) stars across M31, which shows prominent dust lanes on only one side of the major axis. The fraction of reddened stars varies systematically from 20% to 80%, which requires that these stars have an exponential scale height h_z that is 0.14+/-0.015 times the exponential scale length (h_r~5.5kpc). M31’s RGB stars must therefore have h_z=770+/-80pc, which is far thicker than the Milky Way’s thin disk, but comparable to its thick disk. The lack of a significant thin disk in M31 is unexpected, but consistent with its interaction history and high disk velocity dispersion. We suggest that asymmetric reddening be used as a generic criteria for identifying “thick disk” dominated systems, and discuss prospects for future 3-dimensional tomographic mapping of the gas and stars in M31.

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J. Dalcanton, E. Bell, Y. Choi, et. al.
Wed, 19 Apr 23
32/58

Comments: 22 pages. Accepted to the Astrophysical Journal

Physical cool-core condensation radius in massive galaxy clusters [GA]

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http://arxiv.org/abs/2304.08810


We investigate the properties of cool cores in an optimally selected sample of 37 massive and X-ray-bright galaxy clusters, with regular morphologies, observed with Chandra. We measured the density, temperature, and abundance radial profiles of their intracluster medium (ICM). From these independent quantities, we computed the cooling (tcool) free-fall (tff), and turbulence (teddy) timescales as a function of radius. By requiring the profile-crossing condition, tcool=teddy=1, we measured the cool-core condensation radius Rccc, within which the balancing feeding and feedback processes generate the turbulent condensation rain and related chaotic cold accretion (CCA). We also constrained the complementary (quenched) cooling flow radius Rqcf, obtained via the condition tcool=25Xtff, that encompasses the region of thermally unstable cooling. We find that in our cluster sample and in the limited redshift range considered (1.3E14<M500<16.6E14 Msun, 0.03<z<0.29), the distribution of Rccc peaks at 0.01r500 and the entire range remains below 0.07r500, with a very weak increase with redshift and no dependence on the cluster mass. We find that Rqcf is typically 3 times larger than Rccc, with a wider distribution, and growing more slowly along Rccc, according to an average relation Rqcf~Rccc^(0.46), with a large intrinsic scatter. We suggest that this sublinear relation can be understood as an effect of the micro rain of pockets of cooled gas flickering in the turbulent ICM, whose dynamical and thermodynamical properties are referred to as “macro weather”. Substituting the classical cool-core radius R(7.7Gyr), we propose that Rqcf is an indicator of the size of the global cores tied to the long-term macro weather, with the inner Rccc closely tracing the effective condensation rain and chaotic cold accretion (CCA) zone that feeds the central supermassive black hole.

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L. Wang, P. Tozzi, H. Yu, et. al.
Wed, 19 Apr 23
33/58

Comments: A&A, in press, 25 pages, 8 figures

Radiometry for Nighttime Sub-Cloud Imaging of Venus' Surface in the Near-InfraRed Spectrum [EPA]

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http://arxiv.org/abs/2304.08585


Does radiometry (e.g., signal-to-noise ratio) limit the performance of near-IR subcloud imaging of our sister planet’s surface at night? It does not. We compute subcloud radiometry using above-cloud observations, an assumed ground temperature, sub-cloud absorption and emission modeling, and Rayleigh scattering simulations. We thus confirm both archival and recent studies that deployment of a modest subcloud camera does enable high-resolution surface imaging.

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B. Sutin, A. Davis, K. Baines, et. al.
Wed, 19 Apr 23
34/58

Comments: 14 pages, 8 figures

Persistent and occasional: searching for the variable population of the ZTF/4MOST sky using ZTF data release 11 [IMA]

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http://arxiv.org/abs/2304.08519


We present a variability, color and morphology based classifier, designed to identify transients, persistently variable, and non-variable sources, from the Zwicky Transient Facility (ZTF) Data Release 11 (DR11) light curves of extended and point sources. The main motivation to develop this model was to identify active galactic nuclei (AGN) at different redshift ranges to be observed by the 4MOST ChANGES project. Still, it serves as a more general time-domain astronomy study. The model uses nine colors computed from CatWISE and PS1, a morphology score from PS1, and 61 single-band variability features computed from the ZTF DR11 g and r light curves. We trained two versions of the model, one for each ZTF band. We used a hierarchical local classifier per parent node approach, where each node was composed of a balanced random forest model. We adopted a 17-class taxonomy, including non-variable stars and galaxies, three transient classes, five classes of stochastic variables, and seven classes of periodic variables. The macro averaged precision, recall and F1-score are 0.61, 0.75, and 0.62 for the g-band model, and 0.60, 0.74, and 0.61, for the r-band model. When grouping the four AGN classes into one single class, its precision, recall, and F1-score are 1.00, 0.95, and 0.97, respectively, for both the g and r bands. We applied the model to all the sources in the ZTF/4MOST overlapping sky, avoiding ZTF fields covering the Galactic bulge, including 86,576,577 light curves in the g-band and 140,409,824 in the r-band. Only 0.73\% of the g-band light curves and 2.62\% of the r-band light curves were classified as stochastic, periodic, or transient with high probability ($P_{init}\geq0.9$). We found that, in general, more reliable results are obtained when using the g-band model. Using the latter, we identified 384,242 AGN candidates, 287,156 of which have $P_{init}\geq0.9$.

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P. Sánchez-Sáez, J. Arredondo, A. Bayo, et. al.
Wed, 19 Apr 23
35/58

Comments: Accepted for publication in Astronomy & Astrophysics. Abstract shortened for arXiv. Tables containing the classifications and features for the ZTF g and r bands, and the labeled sets will be available at CDS. Individual catalogs per class and band, as well as the labeled set catalogs, can be downloaded at Zenodo DOI:10.5281/zenodo.7826045

Tests of modified gravitational wave propagations with gravitational waves [CL]

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http://arxiv.org/abs/2304.09025


Any violation of the fundamental principles of general relativity (GR), including the violations of the equivalence principle and parity/Lorentz symmetries, could induce possible derivations in the gravitational wave (GW) propagations so they can be tested/constrained directly by the GW data. In this letter, we present a universal parametrization for characterizing possible derivations from GW propagations in GR. This parametrization provides a general framework for exploring possible modified GW propagations arising from a large number of modified theories of gravity. With this parameterization, we construct the modified GW waveforms generated by the coalescence of compact binaries with the effects of the gravitational parity/Lorentz violations, then analyze the open data of compact binary merging events detected by LIGO/Virgo/KAGRA collaboration. We do not find any signatures of gravitational parity/Lorentz violations, thereby allowing us to place several of the most stringent constraints on parity/Lorentz violations in gravity and a first constraint on the Lorentz-violating damping effect in GW. This also represents the most comprehensive tests on the modified GW propagations.

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T. Zhu, W. Zhao, J. Yan, et. al.
Wed, 19 Apr 23
36/58

Comments: 6 pages, 3 tables, and 1 figure

Possible origin of AT2021any: a failed GRB from a structured jet [HEAP]

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http://arxiv.org/abs/2304.09051


Searching for afterglows not associated with any gamma-ray bursts (GRBs) is a longstanding goal of transient surveys. These surveys provide the very chance of discovering the so-called orphan afterglows. Recently, a promising orphan afterglow candidate, AT2021any, was found by the Zwicky Transient Facility. Here we perform multi-wavelength fitting of AT2021any with three different outflow models, namely the top-hat jet model, the isotropic fireball model, and the structured Gaussian jet model. Although the three models can all fit the observed light curve well, it is found that the structured Gaussian jet model presents the best result, and thus is preferred by observations. In the framework of the Gaussian jet model, the best-fit Lorentz factor is about 68, which indicates that AT2021any should be a failed GRB. The half-opening angle of the jet and the viewing angle are found to be 0.104 and 0.02, respectively, which means that the jet is essentially observed on-axis. The trigger time of the GRB is inferred to be about 1000 s before the first detection of the orphan afterglow. An upper limit of 21.4% is derived for the radiative efficiency, which is typical in GRBs.

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F. Xu, Y. Huang and J. Geng
Wed, 19 Apr 23
37/58

Comments: 14 pages, 6 figures, 4 tables. Submitted to A&A, comments welcome

Surface pressure impact on nitrogen-dominated USP super-Earth atmospheres [EPA]

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http://arxiv.org/abs/2304.08690


In this paper, we compare the chemistry and the emission spectra of nitrogen-dominated cool, warm, and hot ultra-short-period (USP) super-Earth atmospheres in and out of chemical equilibrium at various surface pressure scenarios ranging from 0.1 to 10 bar. We link the one-dimensional VULCAN chemical kinetic code, in which thermochemical kinetic and vertical transport and photochemistry are taken into account, to the one-dimensional radiative transfer model, PETITRADTRANS, to predict the emission spectra of these planets. The radiative-convective temperature-pressure profiles were computed with the HELIOS code. Then, using PANDEXO noise simulator, we explore the observability of the differences produced by disequilibrium processes with the JWST. Our grids show how different surface pressures can significantly affect the temperature profiles, the atmospheric abundances, and consequently the emission spectra of these planets. We find that the divergences due to disequilibrium processes would be possible to observe in cooler planets by targeting HCN, C2H4, and CO, and in warmer planets by targeting CH4 with HCN, using the NIRSpec and MIRI LRS JWST instruments. These species are also found to be sensitive indicators of the existence of surfaces on nitrogen-dominated USP super-Earths, providing information regarding the thickness of these atmospheres.

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J. Chouqar, J. Lustig-Yaeger, Z. Benkhaldoun, et. al.
Wed, 19 Apr 23
38/58

Comments: 12 pages

Catching Tidal Dwarf Galaxies at a Later Evolutionary Stage with ALFALFA [GA]

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http://arxiv.org/abs/2304.08552


We present deep optical imaging and photometry of four objects classified as “Almost-Dark” galaxies in the ALFALFA survey because of their gas-rich nature and extremely faint or missing optical emission in existing catalogs. They have HI masses of $10^7$-$10^9$ $M_{\odot}$ and distances of $\sim$9-100 Mpc. Observations with the WIYN 3.5m telescope and One Degree Imager reveal faint stellar components with central surface brightnesses of $\sim$24-25 $\mathrm{mag}\,\mathrm{arcsec}^{-2}$ in the g-band. We also present the results of HI synthesis observations with the Westerbork Synthesis Radio Telescope. These Almost-Dark galaxies have been identified as possible tidal dwarf galaxies (TDGs) based on their proximity to one or more massive galaxies. We demonstrate that AGC 229398 and AGC 333576 likely have the low dark matter content and large effective radii representative of TDGs. They are located much farther from their progenitors than previously studied TDGs, suggesting they are older and more evolved. AGC 219369 is likely dark matter dominated, while AGC 123216 has a dark matter content that is unusually high for a TDG, but low for a normal dwarf galaxy. We consider possible mechanisms for the formation of the TDG candidates such as a traditional major merger scenario and gas ejection from a high velocity fly-by. Blind HI surveys like ALFALFA enable the detection of gas-rich, optically faint TDGs that can be overlooked in other surveys, thereby providing a more complete census of the low-mass galaxy population and an opportunity to study TDGs at a more advanced stage of their life cycle.

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L. Gray, K. Rhode, L. Leisman, et. al.
Wed, 19 Apr 23
39/58

Comments: 38 pages, 26 figures. Accepted by AJ

Astrophysical neutrino point sources as a probe of new physics [CL]

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http://arxiv.org/abs/2304.08533


Recently, the IceCube collaboration observed a neutrino excess in the direction of NGC 1068 with high statistical significance. This constitutes the second detection of an astrophysical neutrino point source after the discovery of a variable emission originating from the blazar TXS~0506+056. Neutrinos emitted by these sources traverse huge, well-determined distances on their way to Earth. This makes them a promising tool to test new physics in the neutrino sector. We consider secret interactions with the cosmic neutrino background and discuss their impact on the flux of neutrino point sources. The observation of emission from NGC 1068 and TXS 0506+056 can then be used to put limits on the strength of the interaction. We find that our ignorance of the absolute neutrino masses has a strong impact and, therefore, we present limits in two benchmark scenarios with the sum of the neutrino masses around their lower and upper limits.

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C. Döring and S. Vogl
Wed, 19 Apr 23
40/58

Comments: 7 pages + appendix, 5 figures

The evolutionary route to form planetary nebulae with central neutron star – white dwarf binaries [HEAP]

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http://arxiv.org/abs/2304.08827


We present a possible evolutionary pathway to form planetary nebulae (PNe) with close neutron star (NS)-white dwarf (WD) binary central stars. By employing a comprehensive binary population synthesis technique we find that the evolution involves two common envelope evolution (CEE) phases and a core collapse supernova explosion between them that forms the NS. Later the lower mass star engulfs the NS as it becomes a red giant, a process that leads to the second CEE phase and to the ejection of the envelope. This leaves a hot horizontal branch star that evolves to become a helium WD and an expanding nebula. Both the WD and the NS power the nebula. The NS in addition might power a pulsar wind nebula inside the expanding PN. From our simulations we find that the Galactic formation rate of NS-WD PNe is $1.8 \times 10^{-5} {\rm yr}^{-1}$ while the Galactic formation rate of all PNe is $0.42 {\rm yr}^{-1}$. There is a possibility that one of the observed Galactic PNe might be a NS-WD PN, and a few NS-WD PNe might exist in the Galaxy. The central binary systems might be sources for future gravitational wave detectors like LISA, and possibly of electromagnetic telescopes.

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I. Ablimit and N. Soker
Wed, 19 Apr 23
41/58

Comments: 8 pages, 4 figures, one appendix with 3 tables; Will be submitted to MNRAS, comments welcome

LIGO-VIRGO constraints on dark matter and leptogenesis triggered by a first order phase transition at high scale [CL]

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http://arxiv.org/abs/2304.08888


We study the possibility of constraining a scenario with high scale first order phase transition (FOPT) responsible for the cogenesis of baryon and dark matter using gravitational wave (GW) (non)-observations. While the FOPT at high scale is responsible for generating baryon asymmetry through leptogenesis and dark matter via the \textit{mass-gain} mechanism, the resulting GW spectrum falls within the ongoing LIGO-VIRGO experimental sensitivity. The dark matter is preferred to be in the non-thermal ballpark with sub-GeV masses and the criteria of successful dark matter relic rules out a large portion of the parameter space consistent with high scale FOPT and successful leptogenesis. Some part of the parameter space allowed from dark matter and leptogenesis criteria also gives rise to a large signal-to-noise ratio at ongoing experiments and hence can be disfavoured in a conservative way from the non-observation of such stochastic GW background. Future data from ongoing and planned experiments will offer a complementary and indirect probe of the remaining parameter space which is typically outside the reach of any direct experimental probe.

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D. Borah, A. Dasgupta and I. Saha
Wed, 19 Apr 23
42/58

Comments: 15 pages, 5 captioned figures

Combined Spectroscopic and Photometric Analysis of Flares in the Dwarf M Star EV Lacertae [SSA]

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http://arxiv.org/abs/2304.08578


We report results of an observing campaign to study the dwarf M flare star EV Lacertae. Between October 2021 and January 2022 we obtained concurrent B band photometry and low resolution spectroscopy of EV Lac on 39 occasions during 10 of which we observed flares with amplitude greater than 0.1 magnitude. Spectra were calibrated in absolute flux using concurrent photometry and flare-only spectra obtained by subtracting mean quiescent spectra. We measured B band flare energies between Log E = 30.8 and 32.6 erg. In the brightest flares we measured temporal development of flare flux in H I and He I emission lines and in the adjacent continuum and found that flux in the continuum subsided more rapidly than in the emission lines. Although our time resolution was limited, in our brightest flare we saw flux in the continuum clearly peaking before flux in the emission lines. We observed a progressive decrease in flare energy from H\b{eta} to H{\delta}. On average we found 37% of B band flare energy appeared in the H\b{eta} to H{\epsilon} emission lines with the remainder contributing to a rise in continuum flux. We measured black-body temperatures for the brightest flares between 10,500 +- 700 K and 19,500 +- 500 K and found a linear relationship between flare temperature and continuum flux at 4170 {\AA}. Balmer lines in flare-only spectra were well fitted by Gaussian profiles with some evidence of additional short-lived blue-shifted emission at the flare peak.

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D. Boyd, R. Buchheim, S. Curry, et. al.
Wed, 19 Apr 23
43/58

Comments: 12 pages, 13 figures, accepted for publication in the Journal of the AAVSO

Identification of Extended Emission Gamma-Ray-Bursts Candidates using Machine Learning [HEAP]

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http://arxiv.org/abs/2304.08666


Gamma-ray bursts (GRBs) have been traditionally classified based on their duration. The increasing number of extended emission (EE) GRBs, lasting typically more than 2 seconds but with properties similar to those of a short GRBs, challenges the traditional classification criteria. In this work, we use the t-Distributed Stochastic Neighbor Embedding (t-SNE), a machine learning technique, to classify GRBs. We present the results for GRBs observed until July 2022 by the {\itshape Swift}/BAT instrument in all its energy bands. We show the effects of varying the learning rate and perplexity parameters as well as the benefit of pre-processing the data by a non-parametric noise reduction technique. % named {\sc FABADA}. Consistently with previous works, we show that the t-SNE method separates GRBs in two subgroups. We also show that EE GRBs reported by various authors under different criteria tend to cluster in a few regions of our t-SNE maps, and identify seven new EE GRB candidates by using the gamma-ray data provided by the automatic pipeline of {\itshape Swift}/BAT and the proximity with previously identified EE GRBs.

Read this paper on arXiv…

K. Garcia-Cifuentes, R. Becerra, F. Colle, et. al.
Wed, 19 Apr 23
44/58

Comments: Submitted to ApJ after minor comments

The Simons Observatory: Beam characterization for the Small Aperture Telescopes [IMA]

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http://arxiv.org/abs/2304.08995


We use time-domain simulations of Jupiter observations to test and develop a beam reconstruction pipeline for the Simons Observatory Small Aperture Telescopes. The method relies on a map maker that estimates and subtracts correlated atmospheric noise and a beam fitting code designed to compensate for the bias caused by the map maker. We test our reconstruction performance for four different frequency bands against various algorithmic parameters, atmospheric conditions and input beams. We additionally show the reconstruction quality as function of the number of available observations and investigate how different calibration strategies affect the beam uncertainty. For all of the cases considered, we find good agreement between the fitted results and the input beam model within a ~1.5% error for a multipole range l = 30 – 700.

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N. Dachlythra, A. Duivenvoorden, J. Gudmundsson, et. al.
Wed, 19 Apr 23
45/58

Comments: 22 pages, 21 figures, to be submitted to ApJ

The impact of halo concentration on the Sunyaev Zel'dovich effect signal from massive galaxy clusters [CEA]

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http://arxiv.org/abs/2304.08731


The Sunyaev Zel’dovich (SZ) effect is sensitive to the pressure of ionized gas inside galaxy clusters. The gas pressure responds to changes in the gravitational potential of the cluster, which is dominated by the host dark matter halo. Changes in halo concentration therefore impact the SZ signal, with implications for cosmological and other analyses of SZ-selected clusters. We investigate the concentration-SZ relation in theory and simulations. We find that the impact of concentration on the inner SZ profile ($R \lesssim 0.75 R_{200c}$) can be captured with standard polytropic gas models. However, we find that such models do a poor job of reproducing the outer SZ profiles ($R \gtrsim 0.75 R_{200c}$) and the relation between the integrated SZ signal, $Y$, and concentration. This disagreement results from a sharp truncation of the gas pressure profile near the splashback radius, likely caused by virial shocks. We develop a simple description of the truncation that leads to a good match with simulated SZ profiles out to several $R_{200c}$ for clusters of varying mass and concentration, and that also accurately predicts the concentration-$Y$ relationship. Finally, we determine how inference of the linear bias parameter and splashback radius for SZ-selected clusters can be biased by ignoring the concentration dependence of the SZ signal.

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E. Baxter, S. Pandey, S. Adhikari, et. al.
Wed, 19 Apr 23
46/58

Comments: 15 pages, 11 figures; comments welcome!

Star formation in the dwarf Seyfert galaxy NGC 4395: Evidence for both AGN and SNe feedback? [GA]

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http://arxiv.org/abs/2304.08986


We present a detailed multi-wavelength study of star formation in the dwarf galaxy NGC 4395 which hosts an active galactic nucleus (AGN). From our observations with the Ultra-Violet Imaging Telescope, we have compiled a catalogue of 284 star forming (SF) regions, out of which we could detect 120 SF regions in H$\alpha$ observations. Across the entire galaxy, we found the extinction corrected star formation rate (SFR) in the far ultra-violet (FUV) to range from 2.0 $\times$ 10$^{-5}$ M$\odot$yr$^{-1}$ to 1.5 $\times$ 10$^{-2}$ M$\odot$yr$^{-1}$ with a median of 3.0 $\times$ 10$^{-4}$ M$\odot$yr$^{-1}$ and age to lie in the range of $\sim$ 1 to 98 Myr with a median of 14 Myr. In H$\alpha$ we found the SFR to range from 7.2 $\times$ 10$^{-6}$ M$\odot$yr$^{-1}$ to 2.7 $\times$ 10$^{-2}$ M$\odot$yr$^{-1}$ with a median of 1.7 $\times$ 10$^{-4}$ M$\odot$yr$^{-1}$ and age to lie between 3 to 6 Myr with a median of 5 Myr. The stellar ages derived from H$\alpha$ show a gradual decline with galactocentric distance. We found three SF regions close to the center of NGC~4395 with high SFR both from H$\alpha$ and UV which could be attributed to feedback effects from the AGN. We also found six other SF regions in one of the spiral arms having higher SFR. These are very close to supernovae remnants which could have enhanced the SFR locally. We obtained a specific SFR (SFR per unit mass) for the whole galaxy 4.64 $\times$ 10$^{-10}$ yr$^{-1}$.

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P. Nandi, C. Stalin, D. Saikia, et. al.
Wed, 19 Apr 23
47/58

Comments: 10 pages, 11 figures, Accepted for publication in ApJ

Secular orbital dynamics of the innermost exoplanet of the $\upsilon$-Andromedæ system [EPA]

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http://arxiv.org/abs/2304.09038


We introduce a quasi-periodic restricted Hamiltonian to describe the secular motion of a small-mass planet in a multi-planetary system. In particular, we refer to the motion of $\upsilon$-And $b$ which is the innermost planet among those discovered in the extrasolar system orbiting around the $\upsilon$-Andromedae A star. We preassign the orbits of the Super-Jupiter exoplanets $\upsilon$-And $c$ and $\upsilon$-And $d$ in a stable configuration. The Fourier decompositions of their secular motions are reconstructed by using the Frequency Analysis and are injected in the equations describing the orbital dynamics of $\upsilon$-And $b$ under the gravitational effects exerted by those two external exoplanets (expected to be major ones in such an extrasolar system). We end up with a $2+3/2$ degrees of freedom Hamiltonian model; its validity is confirmed by the comparison with several numerical integrations of the complete $4$-body problem. Furthermore, the model is enriched by taking into account also the relativistic effects on the secular motion of the innermost exoplanet. We focus on the problem of the stability of $\upsilon$-And $b$ as a function of the parameters that mostly impact on its orbit, i.e. the initial values of its inclination and the longitude of its node. We study the evolution of its eccentricity, crucial to exclude orbital configurations with high probability of (quasi)collision with the central star in the long-time evolution of the system. Moreover, we also introduce a normal form approach, that further reduces our Hamiltonian model to a system with $2$ degrees of freedom, which is integrable because it admits a constant of motion related to the total angular momentum. This allows us to quickly preselect the domains of stability for $\upsilon$-And $b$, with respect to the set of the initial orbital configurations that are compatible with the observations.

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R. Mastroianni and U. Locatelli
Wed, 19 Apr 23
48/58

Comments: N/A

MHD study of extreme space weather conditions for exoplanets with Earth-like magnetospheres: On habitability conditions and radio-emission [EPA]

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http://arxiv.org/abs/2304.08771


The present study aims at characterizing the habitability conditions of exoplanets with an Earth-like magnetosphere inside the habitable zone of M stars and F stars like tau Boo, caused by the direct deposition of the stellar wind on the exoplanet surface if the magnetosphere shielding is inefficient. In addition, the radio emission generated by exoplanets with a Earth-like magnetosphere is calculated for different space weather conditions. The study is based on a set of MHD simulations performed by the code PLUTO reproducing the space weather conditions expected for exoplanets orbiting the habitable zone of M stars and F stars type tau Boo. Exoplanets hosted by M stars at 0.2 au are protected from the stellar wind during regular and CME-like space weather conditions if the star rotation period is slower than 3 days, that is to say, faster rotators generate stellar winds and interplanetary magnetic fields large enough to endanger the exoplanet habitability. Exoplanets hosted by a F stars type tau Boo at >= 2.5 au are protected during regular space weather conditions, but a stronger magnetic field compared to the Earth is mandatory if the exoplanet is close to the inner edge of the star habitable zone (2.5 au) to shield the exoplanet surface during CME-like space weather conditions. The range of radio emission values calculated in the simulations are consistent with the scaling proposed by [Zarka 2018] during regular and common CME-like space weather conditions. If the radio telescopes measure a relative low radio emission signal with small variability from an exoplanet, that may indicate favorable exoplanet habitability conditions with respect to the space weather states considered and the intrinsic magnetic field of the exoplanet.

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J. Varela, A. Brun, P. Zarka, et. al.
Wed, 19 Apr 23
49/58

Comments: N/A

A Dark Matter Probe in Accreting Pulsar-Black Hole Binaries [HEAP]

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http://arxiv.org/abs/2304.08824


The accretion of dark matter (DM) into astrophysical black holes slowly increases their mass. The rate of this mass accretion depends on the DM model and the model parameters. If this mass accretion effect can be measured accurately enough, it is possible to rule out some DM models, and, with the sufficient technology and the help of other DM constraints, possibly confirm one model. We propose a DM probe based on accreting pulsar-black hole binaries, which provide a high-precision measurement on binary orbital phase shifts induced by DM accretion into black holes, and can help rule out DM models and study the nature of DM.

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A. Akil and Q. Ding
Wed, 19 Apr 23
50/58

Comments: 11 pages, 4 figures

Anisotropic power-law inflation for a generalized model of two scalar and two vector fields [CL]

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http://arxiv.org/abs/2304.08874


Cosmological implication of a generalized model of two scalar and two vector fields, in which both scalar fields are non-minimally coupled to each vector field, is studied in this paper. In particular, we will seek an anisotropic power-law inflationary solution to this model. Furthermore, the stability of the obtained solution will be examined by using the dynamical system approach. As a result, we will show that this solution turns out to be stable and attractive during the inflationary phase as expected due to the existence of the unusual couplings between two scalar and two vector fields. Remarkably, we will point out that the existence of phantom field will lead to an instability of the corresponding anisotropic power-law inflation.

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T. Do and W. Kao
Wed, 19 Apr 23
51/58

Comments: 20 pages, 6 figures. Comments are welcome. arXiv admin note: text overlap with arXiv:2110.13516

On the seed population of solar energetic particles in the inner heliosphere [CL]

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http://arxiv.org/abs/2304.09098


Particles measured in large gradual solar energetic particle (SEP) events are believed to be predominantly accelerated at shocks driven by coronal mass ejections (CMEs). Ion charge state and composition analyses suggest that the origin of the seed particle population for the mechanisms of particle acceleration at CME-driven shocks is not the bulk solar wind thermal material, but rather a suprathermal population present in the solar wind. This suprathermal population could result from remnant material accelerated in prior solar flares and/or preceding CME-driven shocks. In this work, we examine the distribution of this suprathermal particle population in the inner heliosphere by combining a magnetohydrodynamic (MHD) simulation of the solar wind and a Monte-Carlo simulation of particle acceleration and transport. Assuming that the seed particles are uniformly distributed near the Sun by solar flares of various magnitudes, we study the longitudinal distribution of the seed population at multiple heliocentric distances. We consider a non-uniform background solar wind, consisting of fast and slow streams that lead to compression and rarefaction regions within the solar wind. Our simulations show that the seed population at a particular location (e.g., 1 au) is strongly modulated by the underlying solar wind configuration. Corotating interaction regions (CIRs) and merged interactions regions (MIRs) can strongly alter the energy spectra of the seed particle populations. In addition, cross-field diffusion plays an important role in mitigating strong variations of the seed population in both space and energy.

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N. Wijsen, G. Li, Z. Ding, et. al.
Wed, 19 Apr 23
52/58

Comments: 20 pages, 7 figures

Trajectories of astroparticles in pseudo-Finsler spacetime with the most general modified dispersion [CL]

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http://arxiv.org/abs/2304.08676


Finsler geometry is a natural and fundamental generalization of Riemann geometry, and is a tool to research Lorentz invariance violation. We find the connection between the most general modified dispersion relation and a pseudo-Finsler structure, and then we calculate the arrival time delay of astroparticles with different modified dispersion relations in the framework of Finsler geometry. The result suggests that the time delay is irrelevant with the exact form of the modified dispersion relation. If the modified term becomes 0 when $E=p$, there is no arrival time difference, otherwise the time delays only depend on the Lorentz violation scale and the order at which the Lorentz invariance breaks.

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J. Zhu and B. Ma
Wed, 19 Apr 23
53/58

Comments: 9 pages, no figure, version for journal publication

Emerging planetary nebulae within 3D spiral patterns [SSA]

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http://arxiv.org/abs/2304.08668


We present the first 3D radiation-hydrodynamic simulations of the formation of planetary nebulae (PNe) emerging from 3D spiral patterns. We use the GUACHO code to create 3D spiral structures as a consequence of the distortions on the geometry of the intrinsically isotropic wind of an asymptotic giant branch (AGB) star produced by a companion star in a circular orbit. We found that the orbital period of the binary producing the 3D spiral pattern has consequences on the formation and shaping of the PN itself. Stellar systems with longer period create less entwined 3D spirals, producing PNe with rounder inner cavities, and prevent the expansion of jet towards the polar directions. The spiral fitting procedure used in the literature to predict the binary’s orbital period may be misleading in the case of proto-PNe and PNe as spiral patterns are diluted by their own thermal expansion down to the average AGB density profile within a few hundred years and are further disrupted by the action of jets. By adopting a phase of jet ejections between the AGB and post-AGB stages, we are able to recover the morphologies of proto-PNe and PNe that exhibit ring-like structures in their halos.

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V. Lora, J. Toalá, J. González-Carbajal, et. al.
Wed, 19 Apr 23
54/58

Comments: 12 pages, 12 figures, 1 table; Accepted to MNRAS

Hot and highly magnetized neutron star matter properties with Skyrme interactions [CL]

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http://arxiv.org/abs/2304.08776


We study the properties of hot and dense neutron star matter under the presence of strong magnetic fields using two Skyrme interactions, namely the LNS and the BSk21 ones. Asking for $\beta$–stability and charge neutrality, we construct the equation of state of the system and analyze its composition for a range of densities, temperatures and magnetic field intensities of interest for the study of supernova and proto-neutron star matter, with a particular interest on the degree of spin-polarization of the different components. The results show that system configurations with larger fractions of spin up protons and spin down neutrons and electrons are energetically favored over those with larger fractions of spin down protons and spin up neutrons and electrons. The effective mass of neutrons and protons is found to be in general larger for the more abundant of their spin projection component, respectively, spin down neutrons and spin up protons. The effect of the magnetic field on the Helmhotz total free energy density, pressure and isothermal compressibility of the system is almost negligible for all the values of the magnetic field considered.

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O. Benvenuto, E. Bauer and I. Vidaña
Wed, 19 Apr 23
55/58

Comments: 10 pages, 8 figures, 2 tables

Tidal disruption events and quasi periodic eruptions [HEAP]

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http://arxiv.org/abs/2304.08828


Tidal disruption events (TDEs) occur when a star passes close to a massive black hole, so that the tidal forces of the black hole exceed the binding energy of a star and cause it to be ripped apart. Part of the matter will fall onto the black hole, causing a strong increase in the luminosity. Such events are often seen in the optical or the X-ray (or both) or even at other wavelengths such as in the radio, where the diversity of observed emission is still poorly understood. The XMM-Newton catalogue of approximately a million X-ray detections covering 1283$^2$ degrees of sky contains a number of these events. Here I will show the diverse nature of a number of TDEs discovered in the catalogue and discuss their relationship with quasi periodic eruptions.

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N. Webb, D. Barret, O. Godet, et. al.
Wed, 19 Apr 23
56/58

Comments: 7 pages, 1 figure, accepted version for the proceedings of the ‘Black Hole Accretion Under the X-ray Microscope’ Meeting held at ESAC in June 2022. Publisher : Astronomische Nachrichten

The effect of the LMC on the Milky Way system [GA]

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http://arxiv.org/abs/2304.09136


We review the recent theoretical and observational developments concerning the interaction of the Large Magellanic Cloud (LMC) with the Milky Way and its neighbourhood. An emerging picture is that the LMC is a fairly massive companion (10-20% of the Milky Way mass) and just passed the pericentre of its orbit, likely for the first time. The gravitational perturbation caused by the LMC is manifested at different levels. The most immediate effect is the deflection of orbits of stars, stellar streams or satellite galaxies passing in the vicinity of the LMC. Less well known but equally important is the displacement (reflex motion) of central regions of the Milky Way about the centre of mass of both galaxies. Since the Milky Way is not a rigid body, this displacement varies with the distance from the LMC, and as a result, the Galaxy is deformed and its outer regions (beyond a few tens kpc) acquire a net velocity with respect to its centre. These phenomena need to be taken into account at the level of precision warranted by current and future observational data, and improvements on the modelling side are also necessary for an adequate interpretation of these data.

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E. Vasiliev
Wed, 19 Apr 23
57/58

Comments: review article (30 pages)

The cosmic waltz of Coma Berenices and Latyshev 2 (Group X). Membership, phase-space structure, mass, and energy distributions [SSA]

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http://arxiv.org/abs/2304.08618


Context. Open clusters (OCs) are fundamental benchmarks where theories of star formation and stellar evolution can be tested and validated. Coma Ber and Latyshev 2 (Group X) are the second and third OCs closest to the Sun, making them excellent targets to search for low-mass stars and ultra-cool dwarfs. In addition, this pair will experience a flyby in 10-16 Myr which makes it a benchmark to test OCs pair interactions. Aims. We aim at analysing the membership, luminosity, mass, phase-space (i.e., positions and velocities), and energy distributions for Coma Ber and Latyshev 2 and test the hypothesis of the mixing of their populations at the encounter time. Methods. We develop a new phase-space membership methodology and apply it to Gaia data. With the recovered members we infer the phase-space, luminosity and mass distributions using publicly available Bayesian inference codes. Then, with a publicly available orbit integration code and members’ positions and velocities, we integrate their orbits 20 Myr into the future. Results. In Coma Ber, we identify 302 candidate members distributed in the core and tidal tails. The tails are dynamically cold and asymmetrically populated. The stellar system called Group X is made of two structures: the disrupted OC Latyshev 2 (186 candidate members) and a loose stellar association called Mecayotl 1 (146 candidate members), both of them will fly by Coma Ber in $11.3\pm0.5$ Myr and $14.0\pm0.6$ Myr, respectively, and each other in $8.1\pm1.3$ Myr. Conclusions. We study the dynamical properties of the core and tails of Coma Ber and also confirm the existence of the OC Latyshev 2 and its neighbour stellar association Mecayotl 1. Although these three systems will experience encounters we find no evidence supporting the mixing of their populations.

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J. Olivares, N. Lodieu, V. Béjar, et. al.
Wed, 19 Apr 23
58/58

Comments: 25 pages, 19 figures, accepted for publication in Astronomy & Astrophysics

Supermassive primordial black holes: a view from clustering of quasars at $z \sim 6$ [CEA]

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http://arxiv.org/abs/2304.08153


We investigate a scenario where primordial black holes (PBHs) can be the progenitors of supermassive black holes (SMBHs) observed at $z\sim6$. To this end, we carried out clustering analysis using a sample of 81 quasars at $5.88 <z<6.49$, which is constructed in Subaru High-$z$ Exploration of Low-Luminosity Quasars (SHELLQs) project, and 11 quasars in the same redshift range selected from the literature. The resulting angular auto-correlation function (ACF) can be fitted to a power-law form of $\omega_\theta = 0.045^{+0.114}_{-0.106}~\theta^{-0.8}$ over a scale of $0.2!-!10$ degrees. We compare the ACF of the quasars to that predicted for the PBH model at $z\sim 6$ and found that such a scenario is excluded for a broad range of parameter space, from which we can conclude that a scenario with PBHs as SMBHs is not viable. We also discuss a model in which SMBHs at $z \sim 6$ originate from the direct collapse of PBH clumps and argue that the observed ACF excludes such a scenario in the context of our PBH model.

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T. Shinohara, W. He, Y. Matsuoka, et. al.
Tue, 18 Apr 23
1/80

Comments: 23 pages, 7 figures

Geoeffectiveness of Interplanetary Shocks Controlled by Impact Angles: Past Research, Recent Advancements, and Future Work [CL]

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http://arxiv.org/abs/2304.08254


Interplanetary (IP) shocks are disturbances commonly observed in the solar wind. IP shock impacts can cause a myriad of space weather effects in the Earth’s magnetopause, inner magnetosphere, ionosphere, thermosphere, and ground magnetic field. The shock impact angle, measured as the angle the shock normal vector performs with the Sun-Earth line, has been shown to be a very important parameter that controls shock geoeffectivess. An extensive review provided by Oliveira and Samsonov (2018) summarized all the work known at the time with respect to shock impact angles and geomagnetic activity; however, this topic has had some progress since Oliveira and Samsonov (2018) and the main goal of this mini review is to summarize all achievements to date in the topic to the knowledge of the author. Finally, this mini review also brings a few suggestions and ideas for future research in the area of IP shock impact angle geoeffectiveness.

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D. Oliveira
Tue, 18 Apr 23
2/80

Comments: 13 pages, 1 figuew

Toward a 3D kinetic tomography of Taurus clouds: II. A new automated technique and its validation [GA]

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http://arxiv.org/abs/2304.07785


Three-dimensional (3D) kinetic maps of the Milky Way interstellar medium are an essential tool in studies of its structure and of star formation. We aim to assign radial velocities to Galactic interstellar clouds now spatially localized based on starlight extinction and star distances from Gaia and stellar surveys. We developed an automated search for coherent projections on the sky of clouds isolated in 3D extinction density maps on the one hand, and regions responsible for CO radio emissions at specific Doppler shifts on the other hand. The discrete dust structures were obtained by application of the Fellwalker algorithm to a recent 3D extinction density map. For each extinction cloud, a technique using a narrow sliding spectral window moved along the contour-bounded CO spectrum and geometrical criteria was used to select the most likely velocity interval. We applied the new contour-based technique to the 3D extinction density distribution within the volume encompassing the Taurus, Auriga, Perseus and California molecular complexes. From the 45 clouds issued from the decomposition, 42 were assigned a velocity. The remaining structures correspond to very weak CO emission or extinction. We used the non-automated assignments of radial velocities to clouds of the same region presented in paper I and based on KI absorption spectra as a validation test. The new fully automated determinations were found in good agreement with these previous measurements. Our results show that an automated search based on cloud contour morphology can be efficient and that this novel technique may be extended to wider regions of the Milky Way and at larger distance. We discuss its limitations and potential improvements after combination with other techniques.

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Q. Duchêne, C. Hottier, R. Lallement, et. al.
Tue, 18 Apr 23
3/80

Comments: 20 pages, 15 figures, accepted in A&A

Radio AGN Selection and Characterization in Three Deep-Drilling Fields of the Vera C. Rubin Observatory Legacy Survey of Space and Time [GA]

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http://arxiv.org/abs/2304.07864


The Australia Telescope Large Area Survey (ATLAS) and the VLA survey in the XMM-LSS/VIDEO deep field provide deep ($\approx 15$ ${\mu}$Jybeam$^{-1}$) and high-resolution ($\approx$ 4.5–8 arcsec) radio coverage of the three XMM-SERVS fields (W-CDF-S, ELAIS-S1, and XMM-LSS). These data cover a total sky area of 11.3 deg$^2$ and contain $\approx 11000$ radio components. Furthermore, about 3~deg$^2$ of the XMM-LSS field also has deeper MIGHTEE data that achieve a median RMS of 5.6 ${\mu}$Jy beam$^{-1}$ and detect more than 20000 radio sources. We analyze all these radio data and find source counterparts at other wavebands utilizing deep optical and IR surveys. The nature of these radio sources is studied using radio-band properties (spectral slope and morphology), and the IR-radio correlation. %and spectral energy distribution. Radio AGNs are selected and compared with those selected using other methods (e.g. X-ray). We found 1765 new AGNs that were not selected using X-ray and/or MIR methods. We constrain the FIR-to-UV SEDs of radio AGNs using {\sc cigale} and investigate the dependence of radio AGN fraction upon galaxy stellar mass and star-formation rate.

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S. Zhu, W. Brandt, F. Zou, et. al.
Tue, 18 Apr 23
4/80

Comments: 25 pages, 21+3 figures, 8+1 tables, MNRAS accepted. The catalogues are available from this https URL

The Breakthrough Listen Search for Intelligent Life: Nearby Stars' Close Encounters with the Brightest Earth Transmissions [SSA]

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http://arxiv.org/abs/2304.07400


After having left the heliosphere, Voyager 1 and Voyager 2 continue to travel through interstellar space. The Pioneer 10, Pioneer 11, and New Horizons spacecraft are also on paths to pass the heliopause. These spacecraft have communicated with the Deep Station Network (DSN) radio antennas in order to download scientific data and telemetry data. Outward transmissions from DSN travel to the spacecraft and beyond into interstellar space. These transmissions have encountered and will encounter other stars, introducing the possibility that intelligent life in other solar systems will encounter our terrestrial transmissions. We use the beamwidth of the transmissions between DSN and interstellar spacecraft to perform a search around the past and future positions of each spacecraft obtained from the JPL Horizons System. By performing this search over the Gaia Catalogue of Nearby Stars (GCNS), a catalogue of precisely mapped stars within 100 pc, we determine which stars the transmissions of these spacecraft will encounter. We highlight stars that are in the background of DSN transmissions and calculate the dates of these encounters to determine the time and place for potential intelligent extraterrestrial life to encounter terrestrial transmissions.

Read this paper on arXiv…

R. Derrick and H. Isaacson
Tue, 18 Apr 23
5/80

Comments: N/A

Saying Hallo to M94's Stellar Halo: Investigating the Accretion History of the Largest Pseudobulge Host in the Local Universe [GA]

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http://arxiv.org/abs/2304.08436


It is not yet settled how the combination of secular processes and merging gives rise to the bulges and pseudobulges of galaxies. The nearby ($D\sim$ 4.2 Mpc) disk galaxy M94 (NGC 4736) has the largest pseudobulge in the local universe, and offers a unique opportunity for investigating the role of merging in the formation of its pseudobulge. We present a first ever look at M94’s stellar halo, which we expect to contain a fossil record of M94’s past mergers. Using Subaru’s Hyper Suprime-Cam, we resolve and identify red giant branch (RGB) stars in M94’s halo, finding two distinct populations. After correcting for completeness through artificial star tests, we can measure the radial profile of each RGB population. The metal-rich RGB stars show an unbroken exponential profile to a radius of 30 kpc that is a clear continuation of M94’s outer disk. M94’s metal poor stellar halo is detectable over a wider area and clearly separates from its metal-rich disk. By integrating the halo density profile, we infer a total accreted stellar mass of $\sim 2.8 \times 10^8 M_\odot$, with a median metallicity of [M/H] $=-$1.4. This indicates that M94’s most-massive past merger was with a galaxy similar to, or less massive than, the Small Magellanic Cloud. Few nearby galaxies have had such a low-mass dominant merger; therefore we suggest that M94’s pseudobulge was not significantly impacted by merging.

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K. Gozman, E. Bell, A. Smercina, et. al.
Tue, 18 Apr 23
6/80

Comments: 19 pages, 12 figures, 1 table; Published in ApJ on April 14, 2023

Detached and Continuous Circumstellar Matter in Type Ibc Supernovae from Mass Eruption [HEAP]

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http://arxiv.org/abs/2304.08378


Some hydrogen-poor supernovae (SNe) are found to undergo interaction with dense circumstellar matter (CSM) that may originate from mass eruption(s) just prior to core-collapse. We model the interaction between the remaining star and the bound part of the erupted CSM that eventually fall back to the star. We find that while fallback initially results in a continuous CSM down to the star, feedback processes from the star can push the CSM to large radii of $\gtrsim 10^{15}$ cm from several years after the eruption. In the latter case, a tenuous bubble surrounded by a dense and detached CSM extending to $\gtrsim 10^{16}$ cm is expected. Our model offers a natural unifying explanation for the diverse CSM structures seen in hydrogen-poor SNe, such as Type Ibn/Icn SNe that show CSM signatures soon after explosion, and the recently discovered Type Ic SNe 2021ocs and 2022xxf (“the Bactrian”) with CSM signatures seen only at late times.

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D. Tsuna and Y. Takei
Tue, 18 Apr 23
7/80

Comments: 6 pages, 4 Figures. To be submitted to PASJ letters in the weekend

Spectral classification of young stars using conditional invertible neural networks I. Introducing and validating the method [SSA]

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http://arxiv.org/abs/2304.08398


Aims. We introduce a new deep learning tool that estimates stellar parameters (such as effective temperature, surface gravity, and extinction) of young low-mass stars by coupling the Phoenix stellar atmosphere model with a conditional invertible neural network (cINN). Our networks allow us to infer the posterior distribution of each stellar parameter from the optical spectrum.
Methods. We discuss cINNs trained on three different Phoenix grids: Settl, NextGen, and Dusty. We evaluate the performance of these cINNs on unlearned Phoenix synthetic spectra and on the spectra of 36 Class III template stars with well-characterised stellar parameters.
Results. We confirm that the cINNs estimate the considered stellar parameters almost perfectly when tested on unlearned Phoenix synthetic spectra. Applying our networks to Class III stars, we find good agreement with deviations of at most 5–10 per cent. The cINNs perform slightly better for earlier-type stars than for later-type stars like late M-type stars, but we conclude that estimations of effective temperature and surface gravity are reliable for all spectral types within the network’s training range.
Conclusions. Our networks are time-efficient tools applicable to large amounts of observations. Among the three networks, we recommend using the cINN trained on the Settl library (Settl-Net), as it provides the best performance across the largest range of temperature and gravity.

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D. Kang, V. Ksoll, D. Itrich, et. al.
Tue, 18 Apr 23
8/80

Comments: 29 pages, 19 figures, Accepted for publication by Astronomy & Astrophysics on 10. April

The Universe is worth $64^3$ pixels: Convolution Neural Network and Vision Transformers for Cosmology [CEA]

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http://arxiv.org/abs/2304.08192


We present a novel approach for estimating cosmological parameters, $\Omega_m$, $\sigma_8$, $w_0$, and one derived parameter, $S_8$, from 3D lightcone data of dark matter halos in redshift space covering a sky area of $40^\circ \times 40^\circ$ and redshift range of $0.3 < z < 0.8$, binned to $64^3$ voxels. Using two deep learning algorithms, Convolutional Neural Network (CNN) and Vision Transformer (ViT), we compare their performance with the standard two-point correlation (2pcf) function. Our results indicate that CNN yields the best performance, while ViT also demonstrates significant potential in predicting cosmological parameters. By combining the outcomes of Vision Transformer, Convolution Neural Network, and 2pcf, we achieved a substantial reduction in error compared to the 2pcf alone. To better understand the inner workings of the machine learning algorithms, we employed the Grad-CAM method to investigate the sources of essential information in activation maps of the CNN and ViT. Our findings suggest that the algorithms focus on different parts of the density field and redshift depending on which parameter they are predicting. This proof-of-concept work paves the way for incorporating deep learning methods to estimate cosmological parameters from large-scale structures, potentially leading to tighter constraints and improved understanding of the Universe.

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S. Hwang, C. Sabiu, I. Park, et. al.
Tue, 18 Apr 23
9/80

Comments: 20 pages, 9 figures

Measuring the Cosmic X-ray Background in 3-20keV with Straylight from NuSTAR [HEAP]

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http://arxiv.org/abs/2304.07962


By characterizing the contribution of stray light to large datasets from the NuSTAR X-ray observatory collected over 2012–2017, we report a measurement of the cosmic X-ray background in the 3–20 keV energy range. These data represent $\sim20\%$ sky coverage while avoiding Galactic Ridge X-ray emission and are less weighted by deep, survey fields than previous measurements with NuSTAR. Images in narrow energy bands are stacked in detector space and spatially fit with a model representing the stray light and uniform pattern expected from the cosmic X-ray background and the instrumental background, respectively. We establish baseline flux values from Earth-occulted data and validate the fitting method on stray light observations of the Crab, which further serve to calibrate the resulting spectra. We present independent spectra of the cosmic X-ray background with the FPMA and FPMB detector arrays, which are in excellent agreement with the canonical characterization by HEAO 1 and are $10\%$ lower than most subsequent measurements; $F_{\rm{3-20~keV}}^{FPMA} = 2.63 \times 10^{-11}~\rm{erg~s^{-1}~cm^{-2}~deg^{-2}}$ and $F_{\rm{3-20~keV}}^{FPMB} = 2.58 \times 10^{-11}~\rm{erg~s^{-1}~cm^{-2}~deg^{-2}}$. We discuss these results in light of previous measurements of the cosmic X-ray background and consider the impact of systematic uncertainties on our spectra.

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S. Rossland, D. Wik, B. Grefenstette, et. al.
Tue, 18 Apr 23
10/80

Comments: 23 pages, 15 figures, 4 tables

Investigating Time Evolution of Thermal Emission from the Putative Neutron Star in SN 1987A for 50+ Years [HEAP]

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http://arxiv.org/abs/2304.08418


Observations collected with the Atacama Large Millimeter/submillimeter Array (ALMA) and analysis of broadband X-ray spectra have recently suggested the presence of a central compact object (CCO) in SN 1987A. However, no direct evidence of the CCO has been found yet. Here we analyze Chandra X-ray observations of SN 1987A collected in 2007 and 2018, and synthesize the 2027 Chandra and 2037 Lynx spectra of the faint inner region of SN 1987A. We estimate the temporal evolution of the upper limits of the intrinsic luminosity of the putative CCO in three epochs (2018, 2027 and 2037). We find that these upper limits are higher for higher neutron star (NS) kick velocities due to the increased absorption from the surrounding cold ejecta. We compare NS cooling models with both the intrinsic luminosity limits obtained from the X-ray spectra, and the ALMA constraints with the assumption that the observed blob of SN 1987A is primarily heated by thermal emission. We find that the synthetic Lynx spectra are crucial to constrain physical properties of the CCO, which will be confirmed by future observations in the 2040s. We draw our conclusions based on two scenarios, namely the non-detection and detection of NS by Lynx. If the NS is not detected, its kick velocity should be ~700 km/s. Furthermore, the non-detection of the NS would suggest rapid cooling processes around the age of 40 years, implying strong crust superfluidity. Conversely, in the case of NS detection, the mass of the NS envelope must be high.

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A. Dohi, E. Greco, S. Nagataki, et. al.
Tue, 18 Apr 23
11/80

Comments: 37 pages, 17 figures, 6 tables, accepted for publication in ApJ

Spectroscopic follow-up of black hole and neutron star candidates in ellipsoidal variables from Gaia DR3 [SSA]

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http://arxiv.org/abs/2304.07324


We present multi-epoch spectroscopic follow-up of a sample of ellipsoidal variables selected from Gaia DR3 as candidates for hosting quiescent black holes (BHs) and neutron stars (NSs). Our targets were identified as BH/NS candidates because their optical light curves — when interpreted with models that attribute variability to tidal distortion of a star by a companion that contributes negligible light — suggest that the companions are compact objects. From the likely BH/NS candidates identified in recent work accompanying Gaia DR3, we select 14 of the most promising targets for follow-up. We obtained spectra for each object at 2-10 epochs, strategically observing near conjunction to best-constrain the radial velocity semi-amplitude. From the measured semi-amplitudes of the radial velocity curves, we derive minimum companion masses of $M_{2,\min} \leq 0.5 ~ M_{\odot}$ in all cases. Assuming random inclinations, the typical inferred companion mass is $M_2 \sim 0.15 ~ M_{\odot}$. This makes it unlikely that any of these systems contain a BH or NS, and we consider alternative explanations for the observed variability. We can best reproduce the observed light curves and radial velocities with models for unequal-mass contact binaries with starspots. Some of the objects in our sample may also be detached main-sequence binaries, or even single stars with pulsations or starspot variability masquerading as ellipsoidal variation. We provide recommendations for future spectroscopic efforts to further characterize this sample and more generally to search for compact object companions in close binaries.

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P. Nagarajan, K. El-Badry, A. Rodriguez, et. al.
Tue, 18 Apr 23
12/80

Comments: 18 pages, 12 figures

Stability of galaxies across morphological sequence [GA]

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http://arxiv.org/abs/2304.07734


We investigate the stability of nearby disc galaxies and galaxies at redshift ($z$) equal to 4.5. We explore the connection between the stability parameter $(Q_{RW})$, star formation rate ($SFR$), gas fraction $(f^{Gas})$, and the time scale for growth of gravitational instabilities $(\tau)$. We find that, despite differences in morphology $91$ $\%$ of the nearby galaxies have a minimum value of stability parameter ($Q^{Min}{RW}$) greater than $1$ indicating stability against the growth of axisymmetric instabilities. The spirals in our sample have higher median star formation rate, lower median $Q{RW}$, a lower $f^{Gas}$ and small time scale for growth of gravitational instabilities than irregular galaxies. We find that the gravitational instabilities in spirals convert a large fraction of gas into stars quickly, depleting the gas reservoirs. On the other hand, star formation occurs more gradually over longer timescales in irregulars with a higher gas fraction. We then compare the stability of the nearby galaxies with galaxies at $z\,=\,4.5$. We find that net stability levels in the nearby galaxies and the galaxies at $z\,=\,4.5$ are primarily driven by the stellar disc suggesting the presence of an inherent mechanism that self-regulates the stability. Finally, upon removing the contribution of the dark matter to the total potential, the median $Q_{RW}$ for the nearby galaxies and galaxies at $z \,= \,4.5$ remains unchanged indicating that the baryons can self-regulate the stability levels, at least in a statistical sense.

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K. Aditya
Tue, 18 Apr 23
13/80

Comments: Accepted for publication in MNRAS

Noise in the LIGO Livingston Gravitational Wave Observatory due to Trains [IMA]

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http://arxiv.org/abs/2304.07477


Environmental seismic disturbances limit the sensitivity of LIGO gravitational wave detectors. Trains near the LIGO Livingston detector produce low frequency (0.5-10 Hz) ground noise that couples into the gravitational wave sensitive frequency band (10-100 Hz) through light reflected in mirrors and other surfaces. We investigate the effect of trains during the Advanced LIGO third observing run, and propose a method to search for narrow band seismic frequencies responsible for contributing to increases in scattered light. Through the use of the linear regression tool Lasso (least absolute shrinkage and selection operator) and glitch correlations, we identify the most common seismic frequencies that correlate with increases in detector noise as 0.6-0.8 Hz, 1.7-1.9 Hz, 1.8-2.0 Hz, and 2.3-2.5 Hz in the LIGO Livingston corner station.

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J. Glanzer, S. Soni, J. Spoon, et. al.
Tue, 18 Apr 23
14/80

Comments: 18 pages (including bibliography), 17 figures, 2 tables, and 1 appendix. Submitted to Classical and Quantum Gravity

Residual eccentricity of an Earth-like planet orbiting a red giant Sun [EPA]

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http://arxiv.org/abs/2304.07808


The late phases of the orbital evolution of an Earth-like planet around a Sun-like star are revisited considering the effect of the density fluctuations associated with convective motions inside the star. Such fluctuations produce a random perturbation of the stellar outer gravitational field that excites a small residual eccentricity in the orbit of the planet counteracting the effects of tides that tend to circularize the orbit. We compute the power spectrum of the outer gravitational field fluctuations of the star in the quadrupole approximation and study their effects on the orbit of the planet using a perturbative approach. The residual eccentricity is found to be a stochastic variable showing a Gaussian distribution. Adopting a model of the stellar evolution of our Sun computed with MESA, we find that the Earth will be engulfed close to the tip of the red giant branch evolution phase. We find a maximum mean value of the residual eccentricity of about 0.026 immediately before the engulfment. Considering an Earth-mass planet with an initial orbital semimajor axis sufficiently large to escape engulfment, we find that the mean value of the residual eccentricity is greater than 0.01 for an initial separation up to about 1.4 au. The engulfment of the Earth by the red giant Sun is found to be a stochastic process, in contrast to the deterministic character assumed in previous studies. If an Earth-like planet escapes engulfment, its orbit around its remnant white dwarf star will be moderately eccentric. Such a residual eccentricity on the order of a few hundredths can play a relevant role in sustaining the pollution of the white dwarf atmosphere by asteroids and comets as observed in several objects.

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A. Lanza, Y. Lebreton and C. Sallard
Tue, 18 Apr 23
15/80

Comments: 18 pages, 6 figures, 3 appendixes, accepted by Astronomy & Astrophysics

Spectral calculations of 3D RMHD simulations of super-Eddington accretion onto a stellar-mass black hole [HEAP]

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http://arxiv.org/abs/2304.07977


We use the Athena++ Monte Carlo (MC) radiation transfer module to post-process simulation snapshots from non-relativistic Athena++ radiation magnetohydrodynamic (RMHD) simulations. These simulations were run using a gray (frequency integrated) approach but were also restarted and ran with a multi-group approach that accounts for Compton scattering with a Kompaneets operator. These simulations produced moderately super-Eddington accretion rates onto a 6.62 $M_\odot$ black hole. Since we only achieve inflow equilibrium out to 20-25 gravitational radii, we focus on the hard X-ray emission. We provide a comparison between the MC and RMHD simulations showing that the treatment of Compton scattering in the gray RMHD simulations underestimates the gas temperature in the regions above and below the accretion disk. In contrast, the restarted multi-group snapshots provides a treatment for the radiation field that is more consistent with the MC calculations, and result in post-processed spectra with harder X-ray emission compared to their gray snapshot counterparts. We characterize these MC post-processed spectra using commonly employed phenomenological models used for spectral fitting. We also attempt to fit our MC spectra directly to observations of the ultraluminous X-ray source (ULX) NGC 1313 X-1, finding best fit values that are competitive to phenomenological model fits, indicating that first principle models of super-Eddington accretion may adequately explain the observed hard X-ray spectra in some ULX sources.

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B. Mills, S. Davis, Y. Jiang, et. al.
Tue, 18 Apr 23
16/80

Comments: Submitted to ApJ; 20 pages, 15 figures,

Precise Age for the Binary Star System 12 Com in the Coma Berenices Cluster [SSA]

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http://arxiv.org/abs/2304.07397


We present measurements of the interferometrically-resolved binary star system 12 Com and the single giant star 31 Com in the cluster Coma Berenices. 12 Com is a double-lined spectroscopic binary system consisting of a G7 giant and an A3 dwarf at the cluster turnoff. Using an extensive radial velocity dataset and interferometric measurements from PTI and the CHARA array, we measured masses $M_1 =2.64 \pm 0.07 M_\odot$ and $M_2 =2.10 \pm 0.03 M_\odot$. Interferometry also allows us to resolve the giant, and measure its size as $R_1 = 9.12 \pm 0.12 \pm 0.01 R_\odot$. With the measured masses and radii, we find an age of $533 \pm 41 \pm 42$ Myr. For comparison, we measure the radius of 31 Com to be $8.36 \pm 0.15 R_\odot$. Based on the photometry and radius measurements, 12 Com A is likely the most evolved bright star in the cluster, large enough to be in the red giant phase, but too small to have core helium burning. Simultaneous knowledge of 12 Com A’s mass and photometry puts strong constraints on convective core overshooting during the main sequence phase, which in turn reduces systematic uncertainties in the age. Increased precision in measuring this system also improves our knowledge of the progenitor of the cluster white dwarf WD1216+260.

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R. Lam, E. Sandquist, G. Schaefer, et. al.
Tue, 18 Apr 23
17/80

Comments: N/A

Prospects for annihilating dark matter from M31 and M33 observations with the Cherenkov Telescope Array [HEAP]

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http://arxiv.org/abs/2304.08202


M31 and M33 are the closest spiral galaxies and the largest members (together with the Milky Way) of the Local group, which makes them interesting targets for indirect dark matter searches. In this paper we present studies of the expected sensitivity of the Cherenkov Telescope Array (CTA) to an annihilation signal from weakly interacting massive particles from M31 and M33. We show that a 100 h long observation campaign will allow CTA to probe annihilation cross-sections up to $\langle\sigma\upsilon\rangle\approx 5\cdot10^{-25}~\mathrm{cm^{3}s^{-1}}$ for the $\tau^{+}\tau^{-}$ annihilation channel (for M31, at a DM mass of 0.3 TeV), improving the current limits derived by HAWC by up to an order of magnitude. We present an estimate of the expected CTA sensitivity, by also taking into account the contributions of the astrophysical background and other possible sources of systematic uncertainty. We also show that CTA might be able to detect the extended emission from the bulge of M31, detected at lower energies by the Fermi/LAT.

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M. Michailidis, L. Marafatto, D. Malyshev, et. al.
Tue, 18 Apr 23
18/80

Comments: N/A

Model of a `Warm Corona' as the Origin of the Soft X-ray Excess of Active Galactic Nuclei [HEAP]

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http://arxiv.org/abs/2304.07463


The soft X-ray excess in the spectra of active galactic nuclei is characterized by similar electron temperatures of 0.1 — 0.3 keV and similar photon indices around 2.2 — 3. It remains a puzzle why both values are not sensitive to the black hole mass nor accretion rate. Supposing that the scattering-dominated surface layer of an accretion disk can act as a warm corona, we construct a vertically one-zone model to understand what determines its temperature. By solving the equations of (1) the condition for the effective optical depth, (2) the energy balance, and (3) dominance of the Compton cooling over the bound-free cooling, we could reproduce the basic observational features of the soft excess, provided that anomalous heating takes place in the warm corona. The similar temperatures can be understood, since both of the anomalous heating and Compton cooling rates are proportional to the dissipation rate of the accretion energy, while similar photon indices are a natural consequence of the fact that observed photons are finally emitted from the layer of Compton $y\sim 1$. The warm corona solutions only exist at smaller radii, indicating the structure of a warm corona inside and a hot corona outside. The soft excess is not observed in black hole binaries, since disk temperatures are too high for the Compton scattering to work as cooling. The derived temperatures are somewhat underestimation, however. This may indicate a necessity of multi-zone corona structure. The stability of the warm corona and its consequences are briefly discussed.

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N. Kawanaka and S. Mineshige
Tue, 18 Apr 23
19/80

Comments: 21 pages, 4 figures, Comments welcome

Prospects for ultra-high-energy particle acceleration at relativistic shocks [HEAP]

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http://arxiv.org/abs/2304.08132


We study the acceleration of charged particles by ultra-relativistic shocks using test-particle Monte-Carlo simulations. Two field configurations are considered: (i) shocks with uniform upstream magnetic field in the plane of the shock, and (ii) shocks in which the upstream magnetic field has a cylindrical geometry. Particles are assumed to diffuse in angle due to frequent non-resonant scattering on small-scale fields. The steady-state distribution of particles’ Lorentz factors is shown to approximately satisfy $dN/d\gamma \propto \gamma^{-2.2}$ provided the particle motion is scattering dominated on at least one side of the shock. For scattering dominated transport, the acceleration rate scales as $t_{\rm acc}\propto t^{1/2}$, though recovers Bohm scaling $t_{\rm acc}\propto t$ if particles become magnetised on one side of the shock. For uniform field configurations, a limiting energy is reached when particles are magnetised on both sides of the shock. For the cylindrical field configuration, this limit does not apply, and particles of one sign of charge will experience a curvature drift that redirects particles upstream. For the non-resonant scattering model considered, these particles preferentially escape only when they reach the confinement limit determined by the finite system size, and the distribution approaches the escapeless limit $dN/d\gamma \propto \gamma^{-1}$. The cylindrical field configuration resembles that expected for jets launched by the Blandford $\&$ Znajek mechanism, the luminous jets of AGN and GRBs thus provide favourable sites for the production of ultra-high energy cosmic rays.

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Z. Huang, B. Reville, J. Kirk, et. al.
Tue, 18 Apr 23
20/80

Comments: N/A

The role of impact parameter in typical close galaxy flybys [GA]

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http://arxiv.org/abs/2304.07751


Close galaxy flybys, interactions during which two galaxies inter-penetrate, are frequent and can significantly affect the evolution of individual galaxies. Equal-mass flybys are extremely rare and almost exclusively distant, while frequent flybys have mass ratios 0.1 or lower, with a secondary galaxy penetrating deep into the primary. This can result in comparable strengths of interaction S between the two classes of flybys and lead to essentially the same effects. To demonstrate this, emphasize and explore the role of the impact parameter $b$, we performed a series of N-body simulations of flybys with varying relative $b$ ranging from 0.114 to 0.272 of the virial radius of the primary. Two-armed spirals form during flybys, with radii of origin correlated with $b$ and strengths well approximated with an inverted S-curve. The impact parameter does not affect the shape of induced spirals, and the lifetimes of a distinguished spiral structure appear to be constant, 2 Gyr. Bars, with strengths anti-correlated with $b$, form after the encounter is over in simulations with interaction strengths $S\geq0.076$, but they are short-lived except for the stronger ones with $S\geq0.129$. We showcase an occurrence of double bar that survives for a long time in one of the simulations. Effects on the pre-existing bar instability are diverse. There is no uniform correlation between these effects and $b$, as they are secondary effects, happening later in a post-flyby stage. Bulges are resilient to flybys, while dark matter halos can significantly spin up in the amount anti-correlated with $b$. There is an offset angle between the angular momentum vector of the dark matter halo and that of a disc, and it correlates linearly with b. Flybys remain an important pathway for structural evolution within galaxies in the local Universe.

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A. Mitrašinović and M. Micic
Tue, 18 Apr 23
21/80

Comments: 21 pages, 13 figures, accepted for publication in PASA

A hydrodynamic study of the escape of metal species and excited hydrogen from the atmosphere of the hot Jupiter WASP-121b [EPA]

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http://arxiv.org/abs/2304.07352


In the near-UV and optical transmission spectrum of the hot Jupiter WASP-121b, recent observations have detected strong absorption features of Mg, Fe, Ca, and H$\alpha$, extending outside of the planet’s Roche lobe. Studying these atomic signatures can directly trace the escaping atmosphere and constrain the energy balance of the upper atmosphere. To understand these features, we introduce a detailed forward model by expanding the capability of a one-dimensional model of the upper atmosphere and hydrodynamic escape to include important processes of atomic metal species. The hydrodynamic model is coupled to a Ly$\alpha$ Monte Carlo radiative transfer calculation to simulate the excited hydrogen population and associated heating/ionization effects. Using this model, we interpret the detected atomic features in the transmission spectrum of WASP-121b and explore the impact of metals and excited hydrogen on its upper atmosphere. We demonstrate the use of multiple absorption lines to impose stronger constraints on the properties of the upper atmosphere than the analysis of a single transmission feature can provide. In addition, the model shows that line broadening due to atmospheric outflow driven by the Roche lobe overflow is necessary to explain the observed line widths and highlights the importance of the high mass-loss rate caused by the Roche lobe overflow that requires careful consideration of the structure of the lower and middle atmosphere. We also show that metal species and excited state hydrogen can play an important role in the thermal and ionization balance of ultra-hot Jupiter thermospheres.

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C. Huang, T. Koskinen, P. Lavvas, et. al.
Tue, 18 Apr 23
22/80

Comments: 35 pages, 31 figures, Accepted for publication in ApJ

Parallelization of the Symplectic Massive Body Algorithm (SyMBA) $N$-body Code [EPA]

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http://arxiv.org/abs/2304.07325


Direct $N$-body simulations of a large number of particles, especially in the study of planetesimal dynamics and planet formation, have been computationally challenging even with modern machines. This work presents the combination of fully parallelized $N^2/2$ interactions and the incorporation of the GENGA code’s close encounter pair grouping strategy to enable MIMD parallelization of the Symplectic Massive Body Algorithm (SyMBA) with OpenMP on multi-core CPUs in shared-memory environment. SyMBAp (SyMBA parallelized) preserves the symplectic nature of SyMBA and shows good scalability, with a speedup of 30.8 times with 56 cores in a simulation with 5,000 fully interactive particles.

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T. Lau and M. Lee
Tue, 18 Apr 23
23/80

Comments: Accepted for publication in Research Notes of the AAS

Observability of Low-Luminosity AGN in the Early Universe with JWST [GA]

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http://arxiv.org/abs/2304.07369


Active galactic nuclei (AGN) in the early Universe are thought to be prominent sources of energy and ionizing photons that affected the growth of their host galaxy and their environment. However, it is still unclear how the supermassive black holes (SMBHs) that fuel these AGN grew to the observed high masses already at high redshifts. Observations of high-redshift SMBH progenitors or lower-mass AGN will thus help characterize the evolution of SMBHs and their impact on the surroundings. With the launch of the JWST, fainter objects at high redshifts can now be detected, including lower-mass AGN. We assess the observability of such low luminosity AGN, using the cosmological simulation code GIZMO to provide a realistic environment for black hole growth in the early Universe. Soon after the first stars are born in the simulation run, we insert stellar-remnant black hole seeds of various initial masses, between $300$ and $10^4 {\rm \ M}_{\odot}$, at the center of a dark matter halo and follow their growth until $z\sim6$. Such stellar black hole seeds placed in a typical high-$z$ environment do not significantly accrete and grow to reach masses that can be observed with the JWST under conditions of standard Bondi-Hoyle accretion, as energy input from stellar feedback and chaotic dynamics prevent efficient gas accretion onto the black holes. To be observed with the JWST, rarer but still physically feasible growth regimes, involving Eddington or super-Eddington accretion, would be required. Alternatively, AGN observability may be boosted under even rarer conditions of extreme gravitational lensing.

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J. Jeon, B. Liu, V. Bromm, et. al.
Tue, 18 Apr 23
24/80

Comments: 11 pages, 10 figures, submitted to MNRAS

Freeze-in baryogenesis and early matter domination [CL]

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http://arxiv.org/abs/2304.07345


The freeze-in mechanism has been shown to allow the simultaneous generation of cosmic dark matter and a viable matter-antimatter asymmetry in the universe. When the underlying interactions are described by higher-dimensional, non-renormalizable operators, the relevant freeze-in processes take place close to the highest considered cosmic temperatures. In this paper we study how the presence of a fluid that temporarily dominates the energy content of the early universe affects the predictions of this “Ultraviolet Freeze-In Baryogenesis” scenario. We find that this additional cosmic component has a significant impact on the predictions of concrete microscopic models, allowing for reheating temperatures which are much lower than those required in the simplest cosmological scenario. Moreover, we show that inflationary observables can constrain the parameter space of such models, once the latter are examined in conjunction with concrete models of inflation.

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I. Dalianis, A. Goudelis, D. Karamitros, et. al.
Tue, 18 Apr 23
25/80

Comments: 25 pages, 6 figures

On the 5-Minute Oscillations of Photospheric and Chromospheric Swirls [SSA]

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http://arxiv.org/abs/2304.07970


Swirls are ubiquitous in the solar atmosphere. They are believed to be related to the excitation of different modes of magnetohydrodynamic waves and pulses, as well as spicules. However, statistical studies of their collective behaviour are rare. In this paper, we aim to study the collective, as well as the behaviour of individual photospheric and chromospheric swirls detected by the automated swirl detection algorithm (ASDA) from observations obtained by the Swedish 1-m Solar Telescope and the Hinode satellite. Detailed analysis of six different parameters of photospheric and chromospheric swirls is performed employing the wavelet analysis. Two clusters of periods with significant wavelet power, one from $3-8$ minutes and the other from $10-14$ minutes, have been found. The former coincides with the dominant period of the global $p$-mode spectrum. Wavelet and Fast Fourier Transform (FFT) analysis of example swirls also reveals similar periods. These results suggest that global $p$-modes might be important for triggering photospheric and thus chromospheric swirls. A novel scenario of global $p$-modes providing energy and mass fluxes to the upper solar atmosphere via generating swirls, Alfv\’en pulses and spicules is then proposed.

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J. Liu, D. Jess, R. Erdélyi, et. al.
Tue, 18 Apr 23
26/80

Comments: 8 figures and 3 tables, to be published in A&A

Updates to ALMA Site Properties: using the ESO-Allegro Phase RMS database — ALMA Memo 624 [IMA]

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http://arxiv.org/abs/2304.08318


We present a long-term overview of the atmospheric phase stability at the Atacama Large Millimeter/submillimeter Array (ALMA) site, using >5 years of data, that acts as the successor to the studies summarized two decades ago by Evans et al 2003. Importantly, we explore the atmospheric variations, the `phase RMS’, and associated metadata of over 17000 accrued ALMA observations taken since Cycle 3 (2015) by using the Bandpass calibrator source scans. We indicate the temporal phase RMS trends for average baseline lengths of 500, 1000, 5000, and 10000m, in contrast to the old stability studies that used a single 300m baseline phase monitor system. At the ALMA site, on the Chajnantor plateau, we report the diurnal variations and monthly changes in the phase RMS on ALMA relevant baselines lengths, measured directly from data, and we reaffirm such trends in atmospheric transmission (via Precipitable Water Vapour – PWV). We confirm that day observations have respectively higher phase RMS and PWV in contrast to night, while the monthly variations show Chilean winter (June – August) providing the best, high-frequency and long-baseline observing conditions – low (stable) phase RMS and low PWV. Yet, not all good phase stability condition occur when the PWV is low. Measurements of the phase RMS as a function of short timescales, 30 to 240s, that tie with typical target source scan times, and as a function of baseline length indicate that phase variations are smaller for short timescales and baselines and larger for longer timescales and baselines. We illustrate that fast-switching phase-referencing techniques, that allow short target scan times, could work well in reducing the phase RMS to suitable levels specifically for high-frequencies (Band 8, 9 and 10), long-baselines, and the two combined.

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L. Maud, A. Pérez-Sánchez, Y. Asaki, et. al.
Tue, 18 Apr 23
27/80

Comments: 34 pages, 19 Figures, 10 Tables ALMA Memo 624: this https URL

Exotic Image Formation in Strong Gravitational Lensing by Clusters of Galaxies — IV. Elliptical NFW Lenses and Hyperbolic Umbilics [CEA]

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http://arxiv.org/abs/2304.08326


A source lying near hyperbolic umbilic (HU) leads to a ring-like image formation, constituting four images with high magnification factors and lying in a small region of the lens plane. Since (based on our earlier work) the observed number of HU image formations in cluster lenses is expected to increase in future, it is timely to investigate them in more detail. Like fold and cusp, HU also satisfies the magnification relation, i.e., the signed magnification sum of the four images equals zero. This work presents a detailed study of HU magnification relation ($R_{\rm hu}$) considering the elliptical Navarro-Frenk-White (eNFW) lens profile suitable for cluster scale dark matter halos. Our results show that for an isolated eNFW lens, $R_{\rm hu}$ is more sensitive to ellipticity than its mass or concentration parameter. An ellipticity greater than 0.3 results in $R_{\rm hu}$ lying close to zero with a small scatter around it. A substructure near the HU image formation causes the average $R_{\rm hu}$ value to deviate from zero and increases the scatter, with the amount of deviation depending on the image type near which the substructure lies. However, a population of substructures in the lens plane (equivalent to the galaxy lenses inside the cluster) does not significantly shift the average $R_{\rm hu}$ value from zero but increases the scatter around it. We find that $R_{\rm hu} \simeq 0$ for HU image formation in the Abell 1703 cluster. Repeating this test in other clusters where HU formations are discovered can be a useful indicator of substructure in cluster halos.

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A. Meena and J. Bagla
Tue, 18 Apr 23
28/80

Comments: 18 pages, 17 figures. Comments are welcome!

Quarkyonic Model for Neutron Star Matter: A Relativistic Mean-Field Approach [CL]

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http://arxiv.org/abs/2304.08223


The concept of quarkyonic matter presents a promising alternative to the conventional models used to describe high-density matter and provides a more nuanced and detailed understanding of the properties of matter under extreme conditions that exist in astrophysical bodies. The aim of this study is to showcase the effectiveness of utilizing the quarkyonic model, in combination with the relativistic mean-field formalism, to parameterize the equation of state at high densities. Through this approach, we intend to investigate and gain insights into various fundamental properties of a static neutron star, such as its compositional ingredients, speed of sound, mass-radius profile, and tidal deformability. The obtained results revealed that the quarkyonic matter equation of state (EOS) is capable of producing a heavy neutron star with the mass range of $\sim$ $2.8 M_\odot$. The results of our inquiry have demonstrated that the EOS for quarkyonic matter not only yields a neutron star with a significantly high mass but also showcases a remarkable degree of coherence with the conformal limit of the speed of sound originating from deconfined QCD matter. Furthermore, we have observed that the tidal deformability of the neutron star, corresponding to the EOSs of quarkyonic matter, is in excellent agreement with the observational constraints derived from the GW170817 and GW190425 events. This finding implies that the quarkyonic model is capable of forecasting the behavior of neutron stars associated with binary merger systems. This aspect has been meticulously scrutinized in terms of merger time, gravitational wave signatures, and collapse times using numerical relativity simulations.

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A. Kumar, D. Dey, S. Haque, et. al.
Tue, 18 Apr 23
29/80

Comments: N/A

Variable stars in the residual light curves of OGLE-IV eclipsing binaries towards the Galactic Bulge [SSA]

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http://arxiv.org/abs/2304.08394


Context. The Optical Gravitational Lensing Experiment (OGLE) observed around 450,000 eclipsing binaries (EBs) towards the Galactic Bulge. Decade-long photometric observations such as these provide an exceptional opportunity to thoroughly examine the targets. However, observing dense stellar fields such as the Bulge may result in blends and contamination by close objects.
Aims. We searched for periodic variations in the residual light curves of EBs in OGLE-IV and created a new catalogue for the EBs that contain `background’ signals after the investigation of the source of the signal.
Methods. From the about half a million EB systems, we selected those that contain more than 4000 data points. We fitted the EB signal with a simple model and subtracted it. To identify periodical signals in the residuals, we used a GPU-based phase dispersion minimisation python algorithm called cuvarbase and validated the found periods with Lomb-Scargle periodograms. We tested the reliability of our method with artificial light curves.
Results. We identified 354 systems where short-period background variation was significant. In these cases, we determined whether it is a new variable or just the result of contamination by an already catalogued nearby one. We classified 292 newly found variables into EB, $\delta$ Scuti, or RR Lyrae categories, or their sub-classes, and collected them in a catalogue. We also discovered four new doubly eclipsing systems and one eclipsing multiple system with a $\delta$ Scuti variable, and modelled the outer orbits of the components.

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R. Ádám, T. Hajdu, A. Bódi, et. al.
Tue, 18 Apr 23
30/80

Comments: 22 pages, 17 figures, 7 tables, accepted for publication in Astronomy & Astrophysics

Three-dimensional magnetic field imaging of protoplanetary disks using Zeeman broadening and linear polarization observations [EPA]

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http://arxiv.org/abs/2304.07346


Magnetic fields are predicted to have a crucial impact on the structure, evolution and chemistry of protoplanetary disks. However, a direct detection of the magnetic field towards these objects has yet to be achieved. In order to characterize protoplanetary disk magnetic fields, we investigate the impact of the Zeeman effect on the (polarized) radiative transfer of emission from paramagnetic molecules excited in protoplanetary disks. While the effects of the Zeeman effect are commonly studied in the circular polarization of spectral lines, we perform a comprehensive modeling also of the Zeeman-induced broadening of spectral lines and their linear polarization. We develop simplified radiative transfer models adapted to protoplanetary disks, which we compare to full three-dimensional polarized radiative transfer simulations. We find that the radiative transfer of circular polarization is heavily affected by the expected polarity-change of the magnetic field between opposite sides of the disk. In contrast, Zeeman broadening and linear polarization are relatively unaffected by this sign change due to their quadratic dependence on the magnetic field. We can match our simplified radiative transfer models to full polarization modeling with high fidelity, which in turn allows us to prescribe straight-forward methods to extract magnetic field information from Zeeman broadening and linear polarization observations. We find that Zeeman broadening and linear polarization observations are highly advantageous methods to characterize protoplanetary disk magnetic fields as they are both sensitive probes of the magnetic field and are marginally affected by any sign change of the disk magnetic field. Applying our results to existing circular polarization observations of protoplanetary disk spectral lines suggests that the current upper limits on the toroidal magnetic field strengths have to be raised.

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B. Lankhaar and R. Teague
Tue, 18 Apr 23
31/80

Comments: 22 pages, 10 figures, accepted to A&A

Earth shaped by primordial H$_2$ atmospheres [EPA]

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http://arxiv.org/abs/2304.07845


Earth’s water, intrinsic oxidation state, and metal core density are fundamental chemical features of our planet. Studies of exoplanets provide a useful context for elucidating the source of these chemical traits. Planet formation and evolution models demonstrate that rocky exoplanets commonly formed with hydrogen-rich envelopes that were lost over time. These findings suggest that Earth may also have formed from bodies with H$_2$-rich primary atmospheres. Here we use a self-consistent thermodynamic model to show that Earth’s water, core density, and overall oxidation state can all be sourced to equilibrium between H$_2$-rich primary atmospheres and underlying magma oceans in its progenitor planetary embryos. Water is produced from dry starting materials resembling enstatite chondrites as oxygen from magma oceans reacts with hydrogen. Hydrogen derived from the atmosphere enters the magma ocean and eventually the metal core at equilibrium, causing metal density deficits matching that of Earth. Oxidation of the silicate rocks from solar-like to Earth-like oxygen fugacities also ensues as Si, along with H and O, alloys with Fe in the cores. Reaction with hydrogen atmospheres and metal-silicate equilibrium thus provides a simple explanation for fundamental features of Earth’s geochemistry that is consistent with rocky planet formation across the galaxy.

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E. Young, A. Shahar and H. Schlichting
Tue, 18 Apr 23
32/80

Comments: 3 main figures, 5 auxiliary figures

Empirical measurement of the dynamical ages of three globular clusters and some considerations on the use of the dynamical clock [GA]

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http://arxiv.org/abs/2304.08140


We have used the “dynamical clock” to measure the level of dynamical evolution reached by three Galactic globular clusters (namely, NGC 3201, NGC 6316 and NGC 6440). This is an empirical method that quantifies the level of central segregation of blue stragglers stars (BSSs) within the cluster half-mass radius by means of the $A^+{rh}$ parameter, defined as the area enclosed between the cumulative radial distribution of BSSs and that of a lighter population. The total sample with homogeneous determinations of $A^+{rh}$ now counts a gran-total of 59 clusters: 52 old GCs in the Milky Way (including the three investigated here), 5 old clusters in the Large Magellanic Cloud, and 2 young systems in the Small Magellanic Cloud. The three objects studied here nicely nest into the correlation between $A^+_{rh}$ and the central relaxation time defined by the previous sample, thus proving and consolidating the use of the dynamical clock as an excellent tracer of the stage of star cluster dynamical evolution in different galactic environments. Finally, we discuss the advantages of using the dynamical clock as an indicator of star cluster dynamical ages, compared to the present-day central relaxation time.

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F. Ferraro, B. Lanzoni, E. Vesperini, et. al.
Tue, 18 Apr 23
33/80

Comments: 16 pages and 8 figures, in press in the ApJ

Gas selection for Xe-based LCP-GEM detectors onboard the CubeSat X-ray observatory NinjaSat [IMA]

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http://arxiv.org/abs/2304.08321


We present a gas selection for Xe-based gas electron multiplier (GEM) detectors, Gas Multiplier Counters (GMCs) onboard the CubeSat X-ray observatory NinjaSat. To achieve an energy bandpass of 2-50 keV, we decided to use a Xe-based gas mixture at a pressure of 1.2 atm that is sensitive to high-energy X-rays. In addition, an effective gain of over 300 is required for a single GEM so that the 2 keV X-ray signal can be sufficiently larger than the electrical noise. At first, we measured the effective gains of GEM in nine Xe-based gas mixtures (combinations of Xe, Ar, CO2, CH4, and dimethyl ether; DME) at 1.0 atm. The highest gains were obtained with Xe/Ar/DME mixtures, while relatively lower gains were obtained with Xe/Ar/CO2, Xe/Ar/CH4, and Xe+quencher mixtures. Based on these results, we selected the Xe/Ar/DME (75%/24%/1%) mixture at 1.2 atm as the sealed gas for GMC. Then we investigated the dependence of an effective gain on the electric fields in the drift and induction gaps ranging from 100-650 V cm$^{-1}$ and 500-5000 V cm$^{-1}$, respectively, in the selected gas mixture. The effective gain weakly depended on the drift field while it was almost linearly proportional to the induction field: 2.4 times higher at 5000 V cm$^{-1}$ than at 1000 V cm$^{-1}$. With the optimal induction and drift fields, the flight model GMC achieves an effective gain of 460 with an applied GEM voltage of 590 V.

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T. Takeda, T. Tamagawa, T. Enoto, et. al.
Tue, 18 Apr 23
34/80

Comments: 7th international conference on Micro Pattern Gaseous Detectors 2022 – MPGD2022, 3 pages, 2 figures

Using Dark Energy Explorers and Machine Learning to Enhance the Hobby-Eberly Telescope Dark Energy Experiment [IMA]

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http://arxiv.org/abs/2304.07348


We present analysis using a citizen science campaign to improve the cosmological measures from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). The goal of HETDEX is to measure the Hubble expansion rate, $H(z)$, and angular diameter distance, $D_A(z)$, at $z =$ 2.4, each to percent-level accuracy. This accuracy is determined primarily from the total number of detected Lyman-$\alpha$ emitters (LAEs), the false positive rate due to noise, and the contamination due to [O II] emitting galaxies. This paper presents the citizen science project, Dark Energy Explorers, with the goal of increasing the number of LAEs, decreasing the number of false positives due to noise and the [O II] galaxies. Initial analysis shows that citizen science is an efficient and effective tool for classification most accurately done by the human eye, especially in combination with unsupervised machine learning. Three aspects from the citizen science campaign that have the most impact are 1) identifying individual problems with detections, 2) providing a clean sample with 100% visual identification above a signal-to-noise cut, and 3) providing labels for machine learning efforts. Since the end of 2022, Dark Energy Explorers has collected over three and a half million classifications by 11,000 volunteers in over 85 different countries around the world. By incorporating the results of the Dark Energy Explorers we expect to improve the accuracy on the $D_A(z)$ and $H(z)$ parameters at $z =$ 2.4 by 10 – 30%. While the primary goal is to improve on HETDEX, Dark Energy Explorers has already proven to be a uniquely powerful tool for science advancement and increasing accessibility to science worldwide.

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L. House, K. Gebhardt, K. Finkelstein, et. al.
Tue, 18 Apr 23
35/80

Comments: 14 pages, 6 figures, accepted for publication in The Astrophysical Journal

Exploring the multi-band gravitational wave background with a semi-analytic galaxy formation model [CL]

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http://arxiv.org/abs/2304.08333


The compact binary systems, spanning from the stellar to supermassive black hole, encode a wealth of information concerning stellar evolution, galaxy formation and evolution, and cosmology. An enormous number of these systems, both resolved and unresolved, emit substantial gravitational waves during their final evolutionary stages, thereby creating a stochastic gravitational wave background (SGWB). We calculate the merger rates of stellar compact binaries and massive black hole binaries using a semi-analytic galaxy formation model — Galaxy Assembly with Binary Evolution (GABE) in a unified and self-consistent approach, followed by an estimation of the multi-band SGWB contributed by the binary systems. We find that the amplitudes of the principal peaks of the SGWB energy density are within one order of magnitude $\Omega_{GW} \sim 10^{-9}- 10^{-8}$. This SGWB can be easily detected by the Square Kilometre Array (SKA), as well as planned interferometric detectors, such as the Einstein Telescope (ET) and the Laser Interferometer Space Antenna (LISA). The energy density of this background varies as $\Omega_{GW} \propto f^{2/3}$ in the SKA band. The shape of the SGWB spectrum in the frequency range $\sim[10^{-4}$,$1]$Hz could allow the space-based detector LISA to distinguish the black hole seed models. The amplitude of the SGWB from merging stellar binary black holes (BBHs) at $\sim 100$ Hz is approximately 10 and 100 times greater than those from merging binary neutron stars (BNSs) and neutron-star-black-hole (NSBH) mergers, respectively.

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Z. Li, Z. Jiang, X. Fan, et. al.
Tue, 18 Apr 23
36/80

Comments: 9 pages, 4 figures

First Detection of the BAO Signal from Early DESI Data [CEA]

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http://arxiv.org/abs/2304.08427


We present the first detection of the baryon acoustic oscillations (BAO) signal obtained using unblinded data collected during the initial two months of operations of the Stage-IV ground-based Dark Energy Spectroscopic Instrument (DESI). From a selected sample of 261,291 Luminous Red Galaxies spanning the redshift interval 0.4 < z < 1.1 and covering 1651 square degrees with a 57.9% completeness level, we report a ~5 sigma level BAO detection and the measurement of the BAO location at a precision of 1.7%. Using a Bright Galaxy Sample of 109,523 galaxies in the redshift range 0.1 < z < 0.5, over 3677 square degrees with a 50.0% completeness, we also detect the BAO feature at ~3 sigma significance with a 2.6% precision. These first BAO measurements represent an important milestone, acting as a quality control on the optimal performance of the complex robotically-actuated, fiber-fed DESI spectrograph, as well as an early validation of the DESI spectroscopic pipeline and data management system. Based on these first promising results, we forecast that DESI is on target to achieve a high-significance BAO detection at sub-percent precision with the completed 5-year survey data, meeting the top-level science requirements on BAO measurements. This exquisite level of precision will set new standards in cosmology and confirm DESI as the most competitive BAO experiment for the remainder of this decade.

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J. Moon, D. Valcin, M. Rashkovetskyi, et. al.
Tue, 18 Apr 23
37/80

Comments: 17 pages, 10 figures, 4 tables. Submitted to MNRAS

Multiple Stellar Populations in Globular Clusters with JWST [SSA]

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http://arxiv.org/abs/2304.07770


I present the first evidence of multiple populations in the globular cluster (GCs) 47Tucanae based on images collected with the near-infrared camera (NIRCam) on board the James Webb Space Telescope (JWST). While NIRCam photometry is poorly sensitive to multiple populations among stars brighter than the main-sequence (MS) knee, the M-dwarfs more-massive than 0.1 solar masses define a wide F115W-F322W2 color range due to multiple populations. The star-to-star color differences are mostly due to the different amounts of water vapor (hence oxygen) that affect the spectra of M-dwarfs. The chromosome map unveils an extended first population (1P) composed of M-dwarfs with different metallicities and three main groups of second-population (2P) stars that are depleted in oxygen with respect to the 1P. I present the discovery of an MS of very-low-mass stars (masses smaller than 0.1 solar masses) and tentatively associated it with a sequence composed of O-rich stars alone.

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A. Milone
Tue, 18 Apr 23
38/80

Comments: Four pages and two figures. Proceedings of the IAUS 377: Early Disk-Galaxy Formation from JWST to the Milky Way. Kuala-Lumpur,February 6-10, 2023

Observing atmospheric escape in sub-Jovian worlds with JWST [EPA]

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http://arxiv.org/abs/2304.07792


Hydrodynamic atmospheric escape is considered an important process that shapes the evolution of sub-Jovian exoplanets, particularly those with short orbital periods. The metastable He line in the near-infrared at $1.083$ $\mu$m is a reliable tracer of atmospheric escape in hot exoplanets, with the advantage of being observable from the ground. However, observing escaping He in sub-Jovian planets has remained challenging due to the systematic effects and telluric contamination present in ground-based data. With the successful launch and operations of JWST, we now have access to extremely stable high-precision near-infrared spectrographs in space. Here we predict the observability of metastable He with JWST in two representative and previously well-studied warm Neptunes, GJ 436 b ($T_{\rm eq} = 687~{\rm K}$, $R_{\rm p} = 0.37~{\rm R_J}$) and GJ 1214 b ($T_{\rm eq} = 588~{\rm K}$, $R_{\rm p} = 0.25~{\rm R_J}$). Our simulated JWST observations for GJ 436 b demonstrate that a single transit with NIRSpec/G140H is sensitive to mass loss rates that are two orders of magnitude lower than what is detectable from the ground. Our exercise for GJ 1214 b show that the best configuration to observe the relatively weak outflows of warm Neptunes with JWST is with NIRSpec/G140H, and that NIRSpec/G140M and NIRISS/SOSS are less optimal. Since none of these instrument configurations can spectrally resolve the planetary absorption, we conclude that the 1D isothermal Parker-wind approximation may not be sufficient for interpreting such observations. More sophisticated models are critical for breaking the degeneracy between outflow temperature and mass-loss rate for JWST measurements of metastable He.

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L. Santos, M. Alam, N. Espinoza, et. al.
Tue, 18 Apr 23
39/80

Comments: 14 pages, 7 figures, under review at AAS Journals; this version follows the first round of revision. Feedback from the community is welcome

Revisiting the Lithium abundance problem in Big-Bang nucleosynthesis [CL]

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http://arxiv.org/abs/2304.08032


One of the three testaments in favor of the big bang theory is the prediction of the primordial elemental abundances in the big-bang nucleosynthesis (BBN). The Standard BBN is a parameter-free theory due to the precise knowledge of the baryon-to-photon ratio of the Universe obtained from studies of the anisotropies of cosmic microwave background radiation. Although the computed abundances of light elements during primordial nucleosynthesis and those determined from observations are in good agreement throughout a range of nine orders of magnitude, there is still a disparity of $^7$Li abundance overestimated by a factor of $\sim 2.5$ when calculated theoretically. The number of light neutrino flavors, the neutron lifetime and the baryon-to-photon ratio in addition to the astrophysical nuclear reaction rates determine the primordial abundances. We previously looked into the impact of updating baryon-to-photon ratio and neutron lifetime and changing quite a few reaction rates on the yields of light element abundances in BBN. In this work, calculations are performed using new reaction rates for $^3$H(p,$\gamma$)$^4$He, $^6$Li(p,$\gamma$)$^7$Be, $^7$Be(p,$\gamma$)$^8$B, $^{13}$N(p,$\gamma$)$^{14}$O, $^7$Li(n,$\gamma$)$^8$Li and $^{11}$B(n,$\gamma$)$^{12}$B along with the latest measured value of neutron lifetime. We observe from theoretical calculations that these changes result in marginal improvement over a sizable twelve percent reduction in the abundance of $^7$Li achieved earlier.

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V. Singh, D. Bhowmick and D. Basu
Tue, 18 Apr 23
40/80

Comments: 6 pages including 1 table. arXiv admin note: text overlap with arXiv:1708.05567

Proposed Resolution to the Solar Open Magnetic Flux Problem [SSA]

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http://arxiv.org/abs/2304.07649


The solar magnetic fields emerging from the photosphere into the chromosphere and corona are comprised of a combination of “closed” and “open” fields. The closed magnetic field lines are defined as those having both ends rooted in the solar surface, while the open field lines are those having one end extending out into interplanetary space and the other rooted at the Sun’s surface. Since the early 2000’s, the amount of total unsigned open magnetic flux estimated by coronal models have been in significant disagreement with in situ spacecraft observations, especially during solar maximum. Estimates of total open unsigned magnetic flux using coronal hole observations (e.g., using extreme ultraviolet (EUV) or Helium (He) I) are in general agreement with the coronal model results and thus show similar disagreements with in situ observations. While several possible sources producing these discrepancies have been postulated over the years, there is still no clear resolution to the problem. This paper provides a brief overview of the problem and summarizes some proposed explanations for the discrepancies. In addition, two different ways of estimating the total unsigned open magnetic flux are presented, utilizing the Wang-Sheeley-Arge (WSA) model, and one of the methods produce surprisingly good agreement with in situ observations. The findings presented here suggest that active regions residing near the boundaries of mid-latitude coronal holes are the probable source of the missing open flux. This explanation also brings in line many of the seemly contradictory facts that have made resolving this problem so difficult.

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C. Arge, A. Leisner, S. Wallace, et. al.
Tue, 18 Apr 23
41/80

Comments: 14 pages, 5 figures

Chemical Compositions of Red Giant Stars in the Old Open Cluster NGC 7789 [SSA]

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http://arxiv.org/abs/2304.07359


We have gathered optical-region spectra, derived model atmosphere parameters, and computed elemental abundances for 15 red giant stars in the open cluster NGC 7789. We focus on the light element group CNOLi that provides clues to evolutionary changes associated with internal fusion events and chemical mixing. We confirm and extend an early report that NGC 7789 stars 193 and 301 have anomalously large Li abundances, and that these values are apparently unconnected to any other elements’ abundances in these stars. A companion study of He I lambda 10830 lines in both field stars and cluster members shows that star 301 has a strong He feature while star 193 does not. Possible explanations for the large Li abundances of these stars include helium flash-induced mixing events and binary interactions at some past or present times. In either case an internal eruption of energy could cause fresh synthesis of lithium via the Cameron-Fowler Beryllium transport mechanism. Rapid transport of lithium to the outer layers may have created significant chromospheric transient disturbances, producing enough helium ionization to allow for the strong lambda 10830 absorption in star 301.

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N. Nagarajan, C. Sneden, M. Afsar, et. al.
Tue, 18 Apr 23
42/80

Comments: AJ, in press

A high spatial and spectral resolution study of Jupiter's mid-infrared auroral emissions and their response to a solar wind compression [EPA]

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http://arxiv.org/abs/2304.08390


We present mid-infrared spectroscopy of Jupiter’s mid-to-high latitudes using Gemini-North/TEXES (Texas Echelon Cross Echelle Spectrograph) on March 17-19, 2017. These observations capture Jupiter’s hydrocarbon auroral emissions before, during and after the arrival of a solar wind compression on March 18th, which highlights the coupling between the polar stratosphere and external space environment. In comparing observations on March 17th and 19th, we observe a brightening of the CH$_4$, C$_2$H$_2$ and C$_2$H$_4$ emissions in regions spatially coincident with the northern, duskside main auroral emission (henceforth, MAE). In inverting the spectra to derive atmospheric information, we determine that the duskside brightening results from an upper stratospheric (p < 0.1 mbar/z > 200 km) heating (e.g. $\Delta T$ = 9.1 $\pm$ 2.1 K at 9 $\mu$bar at 67.5$^\circ$N, 162.5$^\circ$W) with negligible heating at deeper pressures. Our interpretation is that the arrival of the solar wind enhancement drove magnetospheric dynamics through compression and/or viscous interactions on the flank. These dynamics accelerated currents and/or generated higher Poynting fluxes, which ultimately warmed the atmosphere through Joule heating and ion-neutral collisions. Poleward of the southern MAE, temperature retrievals demonstrate that auroral-related heating penetrates as deep as the 10-mbar level, in contrast to poleward of the northern MAE, where heating is only observed as deep as $\sim$3 mbar. We suggest this results from the south having higher Pedersen conductivities, and therefore stronger currents and acceleration of the neutrals, as well as the poleward heating overlapping with the apex of Jupiter’s circulation thereby inhibiting efficient horizontal mixing/advection.

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J. Sinclair, T. Greathouse, R. Giles, et. al.
Tue, 18 Apr 23
43/80

Comments: N/A

Effective field theories for dark matter pairs in the early universe: cross sections and widths [CL]

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http://arxiv.org/abs/2304.00113


In order to predict the cosmological abundance of dark matter, an estimation of particle rates in an expanding thermal environment is needed. For thermal dark matter, the non-relativistic regime sets the stage for the freeze-out of the dark matter energy density. We compute transition widths and annihilation, bound-state formation, and dissociation cross sections of dark matter fermion pairs in the unifying framework of non-relativistic effective field theories at finite temperature, with the thermal bath modeling the thermodynamical behaviour of the early universe. We reproduce and extend some known results for the paradigmatic case of a dark fermion species coupled to dark gauge bosons. The effective field theory framework allows to highlight their range of validity and consistency, and to identify some possible improvements.

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S. Biondini, N. Brambilla, G. Qerimi, et. al.
Tue, 18 Apr 23
44/80

Comments: 62 pages, 20 figures

LISAmax: Improving the Gravitational-Wave Sensitivity by Two Orders of Magnitude [CL]

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http://arxiv.org/abs/2304.08287


Within its Voyage 2050 planning cycle, the European Space Agency (ESA) is considering long-term large class science mission themes. Gravitational-wave astronomy is among the topics under study. This paper presents “LISAmax”, a gravitational-wave interferometer concept consisting of three spacecraft located close to the Sun-Earth libration points L3, L4 and L5, forming a triangular constellation with an arm length of 259 million kilometers (to be compared to LISA’s 2.5 million kilometer arms). This is the largest triangular formation that can be reached from Earth without a major leap in mission complexity and cost. The sensitivity curve of such a detector is at least two orders of magnitude lower in amplitude than that of LISA. Depending on the choice of other instrument parameters, this makes the detector sensitive to gravitational waves in the micro-Hertz range and opens a new window for gravitational-wave astronomy, not covered by any other planned detector concept. We analyze in detail the constellation stability for a 10-year mission in the full numerical model and compute the orbit transfers using a European launcher and chemical propulsion. The payload design parameters are assessed, and the expected sensitivity curve is compared with a number of potential gravitational-wave sources. No show stoppers are identified at this point of the analysis.

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W. Martens, M. Khan and J. Bayle
Tue, 18 Apr 23
45/80

Comments: 18 pages, 11 figures

The Stellar Spectra Factory (SSF) Based On SLAM [SSA]

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http://arxiv.org/abs/2304.08089


In this work, we present Stellar Spectra Factory (SSF), a tool to generate empirical-based stellar spectra from arbitrary stellar atmospheric parameters. The relative flux-calibrated empirical spectra can be predicted by SSF given arbitrary effective temperature, surface gravity, and metallicity. SSF constructs the interpolation approach based on the SLAM, using ATLAS-A library as the training dataset. SSF is composed of 4 data-driven sub-models to predict empirical stellar spectra. SSF-N can generate spectra from A to K type and some M giant stars, covering 3700 < Teff < 8700 K, 0 < logg < 6 dex, and -1.5 < [M/H] < 0.5 dex. SSF-gM is mainly used to predict M giant spectra with 3520 < Teff < 4000K and -1.5 < [M/H] < 0.4 dex. SSF-dM is for generating M dwarf spectra with 3295 < Teff < 4040K, -1.0 < [M/H] < 0.1 dex. And SSF-B can predict B-type spectra with 9000 < Teff < 24000K and -5.2< MG < 1.5 mag. The accuracy of the predicted spectra is validated by comparing the flux of predicted spectra to those with same stellar parameters selected from the known spectral libraries, MILES and MaStar. The averaged difference of flux over optical wavelength between the predicted spectra and the corresponding ones in MILES and MaStar is less than 5%. More verification is conducted between the magnitudes calculated from the integration of the predicted spectra and the observations in PS1 and APASS bands with the same stellar parameters. No significant systematic difference is found between the predicted spectra and the photomatric observations. The uncertainty is 0.08mag in r band for SSF-gM when comparing with the stars with the same stellar parameters selected from PS1. And the uncertainty becomes 0.31mag in i band for SSF-dM when comparing with the stars with the same stellar parameters selected from APASS.

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W. Ji, C. Liu and B. Zhang
Tue, 18 Apr 23
46/80

Comments: 16 pages, 13 figures

Tabulated Equations of State From Models Informed by Chiral Effective Field Theory [CL]

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http://arxiv.org/abs/2304.07836


We construct four equation of state (EoS) tables, tabulated over a range of temperatures, densities, and charge fractions, relevant for neutron star applications such as simulations of neutron star mergers. The EoS are computed from a relativistic mean-field theory constrained by the pure neutron matter EoS from chiral effective field theory, inferred properties of isospin-symmetric nuclear matter, and astrophysical observations of neutron star structure. To model nuclear matter at low densities, we attach an EoS that models inhomogeneous nuclear matter at arbitrary temperatures and charge fractions. The four EoS tables we develop are available from the CompOSE EoS repository https://compose.obspm.fr/eos/297 and https://gitlab.com/ahaber/qmc-rmf-tables.

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M. Alford, L. Brodie, A. Haber, et. al.
Tue, 18 Apr 23
47/80

Comments: 8 pages, 2 figures

Probing Dark Energy and Modifications of Gravity with Ground-Based Millimeter-Wavelength Line Intensity Mapping [CEA]

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http://arxiv.org/abs/2304.08471


Line intensity mapping (LIM) can provide a powerful means to constrain the theory of gravity and the nature of dark energy at low and high redshifts by mapping the large-scale structure (LSS) over many redshift epochs. In this paper, we investigate the potential of the next generation ground-based millimeter-wavelength LIM surveys in constraining several models beyond $\Lambda$CDM, involving either a dynamic dark energy component or modifications of the theory of gravity. Limiting ourselves to two-point clustering statistics, we consider the measurements of auto-spectra of several CO rotational lines (from J=2-1 to J=6-5) and the [CII] fine structure line in the redshift range of $0.25<z<12$. We consider different models beyond $\Lambda$CDM, each one with different signatures and peculiarities. Among them, we focus on Jordan-Brans-Dicke and axion-driven early dark energy models as examples of well-studied scalar-tensor theories acting at late and early times respectively. Additionally, we consider three phenomenological models based on an effective description of gravity at cosmological scales. We show that LIM surveys deployable within a decade (with $\sim 10^8$ spectrometer hours) have the potential to improve upon the current bounds on all considered models significantly. The level of improvements range from a factor of a few to an order of magnitude.

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A. Dizgah, E. Bellini and G. Keating
Tue, 18 Apr 23
48/80

Comments: 20+3 pages. 15 figures. 3 tables

Measurement of the Cross-Correlation Angular Power Spectrum Between the Stochastic Gravitational Wave Background and Galaxy Over-Density [CL]

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http://arxiv.org/abs/2304.07621


We study the cross-correlation between the stochastic gravitational-wave background (SGWB) generated by binary black hole (BBH) mergers across the universe and the distribution of galaxies across the sky. We use the anisotropic SGWB measurement obtained using data from the third observing run (O3) of Advanced LIGO detectors and galaxy over-density obtained from the Sloan Digital Sky Survey (SDSS) spectroscopic catalog. We compute, for the first time, the angular power spectrum of their cross-correlation. Instead of integrating the SGWB across frequencies, we analyze the cross-correlation in 10 Hz wide SGWB frequency bands to study the frequency dependence of the cross-correlation angular power spectrum. Finally, we compare the observed cross-correlation to the spectra predicted by astrophysical models. We apply a Bayesian formalism to explore the parameter space of the theoretical models, and we set constraints on a set of (effective) astrophysical parameters describing the galactic process of gravitational wave (GW) emission. Parameterizing with a Gaussian function the astrophysical kernel describing the local process of GW emission at galactic scales, we find the 95\% upper limit on kernel amplitude to be $2.7 \times 10^{-32}$ erg cm$^{-3}$s$^{-1/3}$ when ignoring the shot noise in the GW emission process, and $2.16 \times 10^{-32}$ erg cm$^{-3}$s$^{-1/3}$ when the shot noise is included in the analysis. As the sensitivity of the LIGO-Virgo-KAGRA network improves, we expect to be able to set more stringent bounds on this kernel function and constrain its parameters.

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K. Z.Yang, J. Suresh, G. Cusin, et. al.
Tue, 18 Apr 23
49/80

Comments: 19 pages, 12 figures

Primordial Black Holes and Loops in Single-Field Inflation [CEA]

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http://arxiv.org/abs/2304.07801


Using the $\delta N$ formalism we calculate the one-loop correction to the large-scale power spectrum of the curvature perturbation in the standard scenario where primordial black holes are formed in the early universe thanks to a phase of ultra-slow-roll in single-field inflation. We explicitly show that one-loop corrections are negligible when the transition from the ultra-slow-roll to the slow-roll phase is smooth. We conclude that the PBH formation scenario through a ultra-slow-roll phase is viable.

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H. Firouzjahi and A. Riotto
Tue, 18 Apr 23
50/80

Comments: 11 pages

New variable sources revealed by DECam toward the LMC: the first 15 deg2 [SSA]

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http://arxiv.org/abs/2304.08133


The Dark Energy Camera (DECam) is a sensitive, wide field instrument mounted at the prime focus of the 4 m V. Blanco Telescope in Chile. Beside its main objectives, i.e. understanding the growth and evolution of structures in the Universe, the camera offers the opportunity to observe a 3 deg2 field of view in one single pointing and, with an adequate cadence, to identify the variable sources contained. In this paper, we present the result of a DECam observational campaign toward the LMC and give a catalogue of the observed variable sources. We considered all the available DECam observations of the LMC, acquired during 32 nights over a period of two years (from February 2018 to January 2020), and set up a specific pipeline for detecting and characterizing variable sources in the observed fields. Here, we report on the first 15 deg2 in and around the LMC as observed by DECam, testing the capabilities of our pipeline. Since many of the observed fields cover a rather crowded region of the sky, we adopted the ISIS subtraction package which, even in these conditions, can detect variables at a very low signal to noise ratio. All the potentially identified variable sources were then analyzed and each light curve tested for periodicity by using the Lomb-Scargle and Schwarzenberg-Czerny algorithms. Furthermore, we classified the identified sources by using the UPSILoN neural network. This analysis allowed us to find 70 981 variable stars, 1266 of which were previously unknown. We estimated the period of the variables and compared it with the available values in the catalogues. Moreover, for the 1266 newly detected objects, an attempted classification based on light curve analysis is presented.

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A. Franco, A. Nucita, F. Paolis, et. al.
Tue, 18 Apr 23
51/80

Comments: 11 pages, 7 figures

Big Bang initial conditions and self-interacting hidden dark matter [CL]

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http://arxiv.org/abs/2304.08454


A variety of supergravity and string models involve hidden sectors where the hidden sectors may couple feebly with the visible sectors via a variety of portals. While the coupling of the hidden sector to the visible sector is feeble its coupling to the inflaton is largely unknown. It could couple feebly or with the same strength as the visible sector which would result in either a cold or a hot hidden sector at the end of reheating. These two possibilities could lead to significantly different outcomes for observables. We investigate the thermal evolution of the two sectors in a cosmologically consistent hidden sector dark matter model where the hidden sector and the visible sector are thermally coupled and their thermal evolution occurs without the assumption of separate entropy conservation for each sector. Within this framework we analyze several phenomena to illustrate their dependence on the initial conditions. These include the allowed parameter space of models, dark matter relic density, proton-dark matter cross section, effective massless neutrino species at BBN time, self-interacting dark matter cross-section, where self-interaction occurs via exchange of dark photon, and Sommerfeld enhancement. Finally fits to the velocity dependence of dark matter cross sections from galaxy scales to the scale of galaxy clusters is given. The analysis indicates significant effects of the initial conditions on the observables listed above. The analysis is carried out within the framework where dark matter is constituted of dark fermions and the mediation between the visible and the hidden sector occurs via the exchange of dark photons. The techniques discussed here may have applications for a wider class of hidden sector models using different mediations between the visible and the hidden sectors to explore the impact of Big Bang initial conditions on observable physics.

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J. Li and P. Nath
Tue, 18 Apr 23
52/80

Comments: 29 pages,10 figures

The apparent absence of forward scattering in the HD 53143 debris disk [EPA]

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http://arxiv.org/abs/2304.07370


HD 53143 is a mature Sun-like star and host to a broad disk of dusty debris, including a cold outer ring of planetesimals near 90 AU. Unlike most other inclined debris disks imaged at visible wavelengths, the cold disk around HD 53143 appears as disconnected “arcs” of material, with no forward scattering side detected to date. We present new, deeper Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) coronagraphic observations of the HD 53143 debris disk and show that the forward scattering side of the disk remains undetected. By fitting our KLIP-reduced observations via forward modeling with an optically thin disk model, we show that fitting the visible wavelength images with an azimuthally symmetric disk with unconstrained orientation results in an unphysical edge-on orientation that is at odds with recent ALMA observations, while constraining the orientation to that observed by ALMA results in nearly isotropically scattering dust. We show that the HD53143 host star exhibits significant stellar variations due to spot rotation and revisit age estimates for this system.

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C. Stark, B. Ren, M. MacGregor, et. al.
Tue, 18 Apr 23
53/80

Comments: 13 pages, 8 figures, 2 tables Accepted for publication in ApJ

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network [CL]

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http://arxiv.org/abs/2304.08393


Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO–Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects.

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L. Collaboration, V. Collaboration, K. Collaboration, et. al.
Tue, 18 Apr 23
54/80

Comments: 28 pages, 11 figures

Strong and Rapid X-ray Variability of the Super-Eddington Accreting Quasar SDSS J081456.10+532533.5 [HEAP]

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http://arxiv.org/abs/2304.07323


We report strong and rapid X-ray variability found from the super-Eddington accreting quasar SDSS J081456.10+532533.5 at $z=0.1197$. It has a black-hole mass of $2.7\times10^{7}{M_{\odot}}$ and a dimensionless accretion rate of $\approx4$ measured from reverberation-mapping observations. It showed weak X-ray emission in the 2021 February Chandra observation, with the 2 keV flux density being $9.6^{+11.6}{-4.6}$ times lower compared to an archival Swift observation. The 2 keV flux density is also $11.7^{+9.6}{-6.3}$ times weaker compared to the expectation from its optical/UV emission. In a follow-up XMM-Newton observation 32 days later, the 2 keV flux density increased by a factor of $5.3^{+6.4}_{-2.4}$, and the spectra are best described by a power law modified with partial-covering absorption; the absorption-corrected intrinsic continuum is at a nominal flux level. Nearly simultaneous optical spectra reveal no variability, and there is only mild long-term optical/infrared variability from archival data (with a maximum variability amplitude of $\approx50\%$). We interpret the X-ray variability with an obscuration scenario, where the intrinsic X-ray continuum does not vary but the absorber has variable column density and covering factor along the line of sight. The absorber is likely the small-scale clumpy accretion wind that has been proposed to be responsible for similar X-ray variability in other super-Eddington accreting quasars.

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J. Huang, B. Luo, W. Brandt, et. al.
Tue, 18 Apr 23
55/80

Comments: 16 pages, 8 figures, accepted for publication in ApJ

Probing the solar interior with lensed gravitational waves from known pulsars [SSA]

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http://arxiv.org/abs/2304.08220


When gravitational waves (GWs) from a spinning neutron star arrive from behind the Sun, they are subjected to gravitational lensing that imprints a frequency-dependent modulation on the waveform. This modulation traces the projected solar density and gravitational potential along the path as the Sun passes in front of the neutron star. We calculate how accurately the solar density profile can be extracted from the lensed GWs using a Fisher analysis. For this purpose, we selected three promising candidates (the highly spinning pulsars J1022+1001, J1730-2304, and J1745-23) from the pulsar catalog of the Australia Telescope National Facility. The lensing signature can be measured with $3 \sigma$ confidence when the signal-to-noise ratio (SNR) of the GW detection reaches $100 \, (f/300 {\rm Hz})^{-1}$ over a one-year observation period (where $f$ is the GW frequency). The solar density profile can be plotted as a function of radius when the SNR improves to $\gtrsim 10^4$.

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R. Takahashi, S. Morisaki and T. Suyama
Tue, 18 Apr 23
56/80

Comments: 12 pages, 12 figures; submitted to ApJ; a numerical code of the amplification factor for solar lensing is available at this http URL

Evidence for Misalignment Between Debris Disks and Their Host Stars [EPA]

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http://arxiv.org/abs/2304.07446


We place lower limits on the obliquities between debris disks and their host stars for 31 systems by comparing their disk and stellar inclinations. While previous studies did not find evidence for misalignment, we identify 6 systems with minimum obliquities falling between ~30{\deg}-60{\deg}, indicating that debris disks can be significantly misaligned with their stars. These high-obliquity systems span a wide range of stellar parameters with spectral types K through A. Previous works have argued that stars with masses below 1.2 $M_\odot$ (spectral types of ~F6) have magnetic fields strong enough to realign their rotation axes with the surrounding disk via magnetic warping; given that we observe high obliquities for relatively low-mass stars, magnetic warping alone is likely not responsible for the observed misalignment. Yet, chaotic accretion is expected to result in misalignments of ~20{\deg} at most and cannot explain the larger obliquities found in this work. While it remains unclear how primordial misalignment might occur and what role it plays in determining the spin-orbit alignment of planets, future work expanding this sample is critical towards understanding the mechanisms that shape these high-obliquity systems.

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S. Hurt and M. MacGregor
Tue, 18 Apr 23
57/80

Comments: Accepted to The Astrophysical Journal (ApJ)

Dark matter search with CMB: a study of foregrounds [CEA]

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http://arxiv.org/abs/2304.07793


The energy injected from dark matter annihilation and decay processes potentially raises the ionisation of the intergalactic medium and leaves visible footprints on the anisotropy maps of the cosmic microwave background (CMB). Galactic foregrounds emission in the microwave bands contaminate the CMB measurement and may affect the search for dark matter’s signature. In this paper, we construct a full CMB data and foreground simulation based on the design of the next-generation ground-based CMB experiments. The foreground residual after the components separation on maps is fully considered in our data analysis, accounting for various contamination from the emission of synchrotron, thermal dust, free-free and spinning dust. We analyse the corresponding sensitivity on dark matter parameters from the temperature and polarization maps, and we find that the CMB foregrounds leave a non-zero yet controllable impact on the sensitivity. Comparing with statistics-only analysis, the CMB foreground residual leads to a factor of 7%-23% weakening on energy-injection constraints, depending on the specific dark matter process and experimental configuration. Strong limits on dark matter annihilation rate and decay lifetime can be expected after foreground subtraction.

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Z. Zhang, Y. Wang, J. Cang, et. al.
Tue, 18 Apr 23
58/80

Comments: 6 figures, 2 tables. The foreground, mask maps and simulated datasets used in this work are available at this https URL

Internal kinematics of {\it GAIA} DR3 wide binaries: anomalous behaviour in the low acceleration regime [GA]

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http://arxiv.org/abs/2304.07322


The {\it Gaia} eDR3 catalogue has recently been used to construct samples of nearby wide binaries to study the internal kinematics of these objects using relative velocities of the two component stars, $\Delta V$, total binary masses, $m_{B}$, and separations, $s$. For $s \gtrsim 0.035$ pc, these binaries probe the low acceleration $a<a_{0}$ regime over which the gravitational anomalies usually attributed to dark matter are observed in the flat rotation curves of spiral galaxies, where $a_{0}\approx 1.2\times 10^{10}$ is the acceleration scale of MOND. Such experiments test the degree of generality of these anomalies, by exploring the same acceleration regime using independent astronomical systems of vastly smaller mass and size. A signal above Newtonian expectations has been observed when $a<a_{0}$, alternatively interpreted as evidence of a modification in the relevant fundamental physics, or as being due to kinematic contaminants affecting the experiment; the presence of undetected stellar components, unbound encounters and spurious projection effects. Here I take advantage of the enhanced DR3 {\it Gaia} catalogue to perform a more rigorous and detailed study of the internal kinematics of wide binaries than what has previously been possible. Having internally determined accurate {\it Gaia} stellar masses and estimates of binary probabilities for each star using spectroscopic information, together with a larger sample of radial velocities, allows for a significant improvement in the analysis of wide binaries and careful exclusion of possible kinematic contaminants. Resulting $\Delta V$ vs. $s$ and $\Delta V$ vs. $m_{B}$ scalings accurately tracing Newtonian expectations for the high acceleration regime, but consistent with the distance and mass velocity scalings observed in spiral galaxies in the low acceleration one, are obtained.

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X. Hernandez
Tue, 18 Apr 23
59/80

Comments: 10 pages, 6 figures, 2 tables

Detection of magnetic galactic binaries in quasi-circular orbit with LISA [HEAP]

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http://arxiv.org/abs/2304.07294


Laser Interferometer Space Antenna (LISA) will observe gravitational waves from galactic binaries (GBs) of white dwarfs or neutron stars. Some of these objects are among the most magnetic astrophysical objects in the Universe. Magnetism, by secularly disrupting the orbit, can eventually affect the gravitational waves emission and could then be potentially detected and characterized after several years of observations by LISA. Currently, the data processing pipeline of the LISA Data Challenge (LDC) for GBs does not consider either magnetism or eccentricity. Recently, it was shown [Bourgoin et al. PRD 105, 124042 (2022)] that magnetism induces a shift on the gravitational wave frequencies. Additionally, it was argued that, if the binary’s orbit is eccentric, the presence of magnetism could be detected by LISA. In this work, we explore the consequences of a future data analysis conducted on quasi-circular and magnetic GB systems using the current LDC tools. We first show that a single eccentric GB can be interpreted as several GBs and this can eventually bias population studies deduced from LISA’s future catalog. Then, we confirm that for quasi-circular orbits, the secular magnetic energy of the system can be inferred if the signal-to-noise ratio of the second harmonic is high enough to be detected by traditional quasi-monochromatic source searching algorithms. LISA observations could therefore bring new insights on the nature and origin of magnetic fields in white dwarfs or neutron stars.

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E. Savalle, A. Bourgoin, C. Poncin-Lafitte, et. al.
Tue, 18 Apr 23
60/80

Comments: 18 pages, 6 figures

Accurate Inverse-Compton Models Strongly Enhance Leptophilic Dark Matter Signals [CL]

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http://arxiv.org/abs/2304.07317


The annihilation of TeV-scale leptophilic dark matter into electron-positron pairs (hereafter $e^+e^-$) will produce a sharp cutoff in the local cosmic-ray $e^+e^-$ spectrum at an energy matching the dark matter mass. At these high energies, $e^+e^-$ cool quickly due to synchrotron interactions with magnetic fields and inverse-Compton scattering with the interstellar radiation field. These energy losses are typically modelled as a continuous process. However, inverse-Compton scattering is a stochastic energy-loss process where interactions are rare but catastrophic. We show that when inverse-Compton scattering is modelled as a stochastic process, the expected $e^+e^-$ flux from dark matter annihilation is about a factor of $\sim$2 larger near the dark matter mass than in the continuous model. This greatly enhances the detectability of heavy dark matter.

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I. John and T. Linden
Tue, 18 Apr 23
61/80

Comments: 7 pages, 9 figures. Appendix adds 4 pages, 3 figures. To be submitted