Category Archives: Cross-listed

Neutron Skin Thickness Dependence of Astrophysical $S$-factor [CL]

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http://arxiv.org/abs/2303.12156


Background: The density dependence of nuclear symmetry energy is crucial in determining several properties of finite nuclei to the neutron stars with mass $\sim$ 1.4 $M_\odot$. The values of neutron skin thickness, isovector giant dipole resonances energies and various nuclear reaction cross-sections in asymmetric nuclei have been utilized to determine the slope of symmetry energy ($L_0$) at the saturation density. Recent PREX-II and CREX measurements of neutron skin thickness in $^{208}$Pb and $^{48}$Ca nuclei yield very different values of $L_0$ which overlap marginally within 90$\%$ confidence interval.
Purpose: Our objective is to demonstrate the role of symmetry energy on the sub-barrier fusion cross-section and the astrophysical $S$-factor for asymmetric nuclei.
Method: The nucleus nucleus potentials are generated using the double folding model (DFM) for three different nucleon-nucleon interactions. These DFM potentials are used for the calculation of the sub-barrier fusion cross-section and the astrophysical $S$-factor. The nucleon densities required for DFM potentials are generated from different families of non-relativistic and relativistic mean-field models which correspond to a wide range of neutron skin thickness or $L_0$.
Results: We have calculated the sub-barrier fusion cross-section for several asymmetric nuclei involving O, Ca, Ni, and Sn isotopes. The results are presented for the barrier parameters, cross-section, and astrophysical $S$-factor for $^{54}$Ca+$^{54}$Ca and $^{124}$Sn+$^{124}$Sn as a function of neutron skin thickness.
Conclusions: The cross-section for the neutron-rich nuclei show a strong dependence on the behavior of symmetry energy or the neutron skin thickness. The increase in skin thickness lowers the height of the barrier as well as its width which enhances the values of the $S$-factor by more than an order of magnitude.

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T. Ghosh, S. Sangeeta, G. Saxena, et. al.
Thu, 23 Mar 23
6/67

Comments: 8 pages, 7 figures

Scattering and conversion of electromagnetic and gravitational waves by Reissner-Nordström black holes: the Regge pole description [CL]

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http://arxiv.org/abs/2303.12656


We investigate the problem of scattering and conversion of monochromatic planar gravitational and electromagnetic waves impinging upon a Reissner-Nordstr\”om black hole using a Regge pole description, i.e., a complex angular momentum approach. For this purpose, we first compute numerically the Regge pole spectrum for various charge-to-mass ratio configurations. We then derive an asymptotic expressions for the lowest Regge poles, and by considering Bohr-Sommerfeld-type quantization conditions, obtain the spectrum of weakly damped quasinormal frequencies from the Regge trajectories. Next, we construct the scattering and conversion amplitudes as well as the total differential cross sections for different processes using both a complex angular momentum representation and a partial wave expansion method. Finally, we provide an analytical approximation of the scattering and conversion cross sections of different processes from asymptotic expressions for the lowest Regge poles and the associated residues based on the correspondence Regge poles, “surface waves” propagating close to the photon (graviton) sphere. This allows us to extract the physical interpretation encoded in the partial wave expansions in the high-frequency regime (i.e., in the short-wavelength regime), and to describe semiclassically with very good agreement both black hole glory and a large part of the orbiting oscillations, thus unifying these two phenomena from a purely wave point of view.

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M. Hadj
Thu, 23 Mar 23
12/67

Comments: N/A

Dark Matter spikes around Sgr A* in $γ$-rays [CL]

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http://arxiv.org/abs/2303.12107


We use H.E.S.S. $\gamma$-ray observations of Sgr A* to derive novel limits on the Dark Matter (DM) annihilation cross-section. We quantify their dependence on uncertainties i) in the DM halo profile, which we vary from peaked to cored, and ii) in the shape of the DM spike around Sgr A*, dynamically heated by the nuclear star cluster. For peaked halo profiles and depending on the heating of the spike, our limits are the strongest existing ones for DM masses above a few TeV. Our study contributes to assessing the influence of the advancements in our knowledge of the Milky Way on determining the properties of DM particles.

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S. Balaji, D. Sachdeva, F. Sala, et. al.
Thu, 23 Mar 23
13/67

Comments: 19 pages, 6 figures

Flavor solitons in dense neutrino gases [CL]

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http://arxiv.org/abs/2303.12143


We consider a dense neutrino gas in the “fast-flavor limit” (vanishing neutrino masses). For the first time, we identify exact solutions of the nonlinear wave equation in the form of solitons. They can propagate with both sub- or superluminal speed, the latter not violating causality. The soliton with infinite speed is a homogeneous solution and coincides with the usual fast-flavor pendulum except that it swings only once instead of being periodic. The subluminal soliton in the static limit corresponds to a one-swing “spatial pendulum”. A necessary condition for such solutions to exist is a “crossed” neutrino angle distribution. Based on the Nyquist criterion, we derive a new sufficient condition without solving the dispersion relation. The solitons are very fragile: they are as unstable as the homogeneous neutrino gas alone. Moreover, in the presence of matter, only the solution survives that is homogeneous in a frame comoving with the matter current. Generally, the matter effect cannot be eliminated by transformations in flavor space, but instead has a real physical impact.

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D. Fiorillo and G. Raffelt
Thu, 23 Mar 23
53/67

Comments: 12 pages, 8 figures, plus appendices

The Strong Force meets the Dark Sector: a robust estimate of QCD uncertainties for anti-matter dark matter searches [CL]

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http://arxiv.org/abs/2303.11363


In dark-matter annihilation channels to hadronic final states, stable particles — such as positrons, photons, antiprotons, and antineutrinos — are produced via complex sequences of phenomena including QED/QCD radiation, hadronisation, and hadron decays. These processes are normally modelled by Monte Carlo event generators whose limited accuracy imply intrinsic QCD uncertainties on the predictions for indirect-detection experiments like Fermi-LAT, Pamela, IceCube or AMS-02. In this article, we perform a complete analysis of QCD uncertainties in antimatter spectra from dark-matter annihilation, based on parametric variations of the Pythia 8 event generator. After performing several retunings of light-quark fragmentation functions, we define a set of variations that span a conservative estimate of the QCD uncertainties. We estimate the effects on antimatter spectra for various annihilation channels and final-state particle species, and discuss their impact on fitted values for the dark-matter mass and thermally-averaged annihilation cross section. We find dramatic impacts which can go up to $\mathcal{O}(40)$ GeV for uncertainties on the dark-matter mass and up to $\mathcal{O}(10\%)$ for the annihilation cross section. We provide the spectra in tabulated form including QCD uncertainties and code snippets to perform fast dark-matter fits, in this https://github.com/ajueid/qcd-dm.github.io.git repository.

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A. Jueid, J. Kip, R. Austri, et. al.
Wed, 22 Mar 23
3/68

Comments: v1: 52 pages, 21 figures, and 9 tables

Gauge invariance on the light-cone: curvature perturbations and radiative degrees of freedom [CL]

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http://arxiv.org/abs/2303.11743


We derive the expressions on the observed light-cone for some relevant cosmological gauge invariant variables, such as the Mukhanov-Sasaki variable and $E$- and $B$- modes of the tensor perturbations. Since the structure of the light-cone does not reflect in a direct way the FLRW symmetries, we develop a formalism which is coordinate independent and classifies the perturbations according to their helicities. Even though we work with linear perturbations, our formalism can be readily extended to non-linear theory and put the basis to study the evolution of cosmological perturbations, since the early- until the the late-time Universe, directly along the observed light-cone.

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G. Fanizza, G. Marozzi and M. Medeiros
Wed, 22 Mar 23
10/68

Comments: 34 pages, 1 table

Limits on Dark Matter Annihilation from the Shape of Radio Emission in M31 [CL]

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http://arxiv.org/abs/2303.11354


Well-motivated scenarios of thermally-produced dark matter often result in a population of electrons and positrons within galaxies produced through dark matter annihilation — often in association with high-energy gamma rays. As they diffuse through galactic magnetic fields, these $e^\pm$ produce synchrotron radio emission. The intensity and morphology of this signal depends on the properties of the interstellar medium through which the $e^\pm$ propagate. Using observations of the Andromeda Galaxy (M31) to construct a model of the gas, magnetic fields, and starlight, we set constraints on dark matter annihilation to $b\bar{b}$ using the morphology of 3.6 cm radio emission. As the emission signal at the center of M31 is very sensitive to the diffusion coefficient and dark matter profile, we base our limits on the differential flux in the region between $0.9-6.9$ kpc from the center. We exclude annihilation cross sections $\gtrsim 3 \times 10^{-25}$ cm$^3$/s in the mass range $10-500$ GeV, with a maximum sensitivity of $7\times 10^{-26}$ cm$^3$/s at $20-40$ GeV. Though these limits are weaker than those found in previous studies of M31, they are robust to variations of the diffusion coefficient.

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M. Weikert and M. Buckley
Wed, 22 Mar 23
20/68

Comments: 34 pages, 27 figures

Relic gravitons and high-frequency detectors [CL]

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http://arxiv.org/abs/2303.11928


Cosmic gravitons are expected in the MHz-GHz regions that are currently unreachable by the operating wide-band interferometers and where various classes of electromechanical detectors have been proposed through the years. The minimal chirp amplitude detectable by these instruments is often set on the basis of the sensitivities reachable by the detectors currently operating in the audio band. By combining the observations of the pulsar timing arrays, the limits from wide-band detectors and the other phenomenological bounds we show that this requirement is far too generous and even misleading since the actual detection of relic gravitons well above the kHz would demand chirp and spectral amplitudes that are ten or even fifteen orders of magnitude smaller than the ones currently achievable in the audio band, for the same classes of stochastic sources. We then examine more closely the potential high-frequency signals and show that the sensitivity in the chirp and spectral amplitudes must be even smaller than the ones suggested by the direct and indirect constraints on the cosmic gravitons. We finally analyze the high-frequency detectors in the framework of Hanbury-Brown Twiss interferometry and argue that they are actually more essential than the ones operating in the audio band (i.e. between few Hz and few kHz) if we want to investigate the quantumness of the relic gravitons and their associated second-order correlation effects. We suggest, in particular, how the statistical properties of thermal and non-thermal gravitons can be distinguished by studying the corresponding second-order interference effects.

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M. Giovannini
Wed, 22 Mar 23
22/68

Comments: 42 pages, 13 figures

Axion-sourced fireballs from supernovae [CL]

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http://arxiv.org/abs/2303.11395


New feebly interacting particles would emerge from a supernova core with 100-MeV-range energies and produce $\gamma$-rays by subsequent decays. These would contribute to the diffuse cosmic $\gamma$-ray background or would have shown up in the Solar Maximum Mission (SMM) satellite from SN~1987A. However, we show for the example of axion-like particles (ALPs) that, even at distances beyond the progenitor star, the decay photons may not escape, and can instead form a fireball, a plasma shell with $T\lesssim 1$ MeV. Thus, existing arguments do not exclude ALPs with few 10 MeV masses and a two-photon coupling of a few $10^{-10}~{\rm GeV}^{-1}$. However, the energy would have showed up in sub-MeV photons, which were not seen from SN 1987A in the Pioneer Venus Orbiter (PVO), closing again this new window. A careful re-assessment is required for other particles that were constrained in similar ways.

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M. Diamond, D. Fiorillo, G. Marques-Tavares, et. al.
Wed, 22 Mar 23
24/68

Comments: 11 pages, 6 figures

The physics of gravitational waves [CL]

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http://arxiv.org/abs/2303.11713


These lecture notes collect the material that I have been using over the years for various short courses on the physics of gravitational waves, first at the Institut d’Astrophysique de Paris (France), and then at SISSA (Italy) and various summer/winter schools. The level should be appropriate for PhD students in physics or for MSc students that have taken a first course in general relativity. The focus is on deriving results from first principles, rather than on astrophysical applications.

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E. Barausse
Wed, 22 Mar 23
33/68

Comments: 52 pages, 14 figures. To be submitted to POS for the proceedings of the September 2022 summer school of the COST Action CA18108 on “Theoretical and experimental approaches to quantum gravity phenomenology” (Belgrade, Serbia)

Bimetric-Affine Quadratic Gravity [CL]

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http://arxiv.org/abs/2303.11353


Bimetric gravity, is a theory of gravity that posits the existence of two interacting and dynamical metric tensors. The spectrum of bimetric gravity consists of a massless and a massive spin-2 particle. The form of the interactions between the two metrics $g_{\mu\nu}$ and $f_{\mu\nu}$ is constrained by requiring absence of the so called Boulware-Deser ghost. In this work we extend the original bimetric theory to its bimetric-affine counterpart, in which the associated two connections, $\Gamma_{ \mu\,\,\,\nu}^{\,\,\,\rho}(g)$ and $\widetilde{\Gamma}_{ \mu\,\,\,\nu}^{\,\,\,\rho}(f)$, are treated as independent variables. We examine in detail the case of an additional quadratic in the Ricci scalar curvature term $\mathcal{R}^2(g)$ and we find that this theory is free of ghosts for a wide range of the interaction parameters, not excluding the possibility of a Dark Matter interpretation of the massive spin-2 particle.

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I. Gialamas and K. Tamvakis
Wed, 22 Mar 23
41/68

Comments: 10 pages, 2 figures

Interacting cosmic strings and Dark matter-For the case of missing stars [CL]

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http://arxiv.org/abs/2303.11955


This work discusses a few theories including the interaction of dark matter, cosmic strings, and locally coupled dark energy. The paper also examines mathematical models used to describe the pressure and density within a star, including the polytropic relationship and the Lane-Emden equation. Simulation results from the IllustrisTNG datasets are also presented, providing insights into the interacting dark matter solutions. With the derived solutions this paper, it explores the possible causes for the sudden disappearance of the star PHL293B-LBV

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N. Shriethar and N. Rajendran
Wed, 22 Mar 23
47/68

Comments: 23 pages, 2 figures

Hunting for Neutral Leptons with Ultra-High-Energy Cosmic Rays [CL]

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http://arxiv.org/abs/2303.11352


Next-generation large-volume detectors, such as GRAND, POEMMA, Trinity, TAROGE-M, and PUEO, have been designed to search for ultra-high-energy cosmic rays (UHECRs) with unprecedented sensitivity. We propose to use these detectors to search for new physics beyond the Standard Model (BSM). By considering the simple case of a right-handed neutrino that mixes exclusively with the active $\tau$ neutrino, we demonstrate that the existence of new physics can increase the probability for UHECRs to propagate through the Earth and produce extensive air showers that will be measurable soon. We compare the fluxes of such showers that would arise from various diffuse and transient sources of high-energy neutrinos, both in the Standard Model and in the presence of a right-handed neutrino. We show that detecting events with emergence angles $\gtrsim 10$ deg is promising to probe the existence of BSM physics, and we study the sensitivity of GRAND and POEMMA to do so. In particular, we show that the hypothesis of a right-handed neutrino with a mass of $\mathcal O(1-16)$ GeV may be probed in the future for mixing angles as small as $|U_{\tau N}|^2 \gtrsim 10^{-7}$, thus competing with existing and projected experimental limits.

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R. Heighton, L. Heurtier and M. Spannowsky
Wed, 22 Mar 23
56/68

Comments: 14 pages, 11 figures

Absorption of Vector Dark Matter Beyond Kinetic Mixing [CL]

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http://arxiv.org/abs/2303.11344


Massive vector particles are minimal dark matter candidates that motivate a wide range of laboratory searches, primarily exploiting a postulated kinetic mixing with the photon. However, depending on the high energy field content, the dominant vector dark matter (VDM) coupling to visible particles may arise at higher operator dimension, motivating efforts to predict direct detection rates for more general interactions. Here we present the first calculation of VDM absorption through its coupling to electron electric (EDM) or magnetic (MDM) dipole moments, which can be realized in minimal extensions to the Standard Model and yield the observed abundance through a variety of mechanisms across the eV\,-\,MeV mass range. We compute the absorption rate of the MDM and EDM models for a general target, and then derive direct detection constraints from targets currently in use: Si and Ge crystals and Xe and Ar atoms. We find that current experiments are already sensitive to VDM parameter space corresponding to a cosmological freeze-in scenario, and future experiments will be able to completely exclude MDM and EDM freeze-in models with reheat temperatures below the electroweak scale. Additionally, we find that while constraints on the MDM interaction can be related to constraints on axion-like particles, the same is not true for the EDM model, so the latter absorption rate must be computed from first principles. To achieve this, we update the publicly available program EXCEED-DM to perform these new calculations.

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G. Krnjaic and T. Trickle
Wed, 22 Mar 23
60/68

Comments: 23 pages, 3 figures

Does gravitational confinement sustain flat galactic rotation curves without dark matter? [CL]

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http://arxiv.org/abs/2303.11094


The short answer is $\textit{probably no}$. Specifically, this paper considers a recent body of work which suggests that general relativity requires neither the support of dark matter halos, nor unconventional baryonic profiles, nor any infrared modification, to be consistent after all with the anomalously rapid orbits observed in many galactic discs. In particular, the gravitoelectric flux is alleged to collapse nonlinearly into regions of enhanced force, in an analogue of the colour-confining chromoelectric flux tube model which has yet to be captured by conventional post-Newtonian methods. However, we show that the scalar gravity model underpinning this proposal is wholly inconsistent with the nonlinear Einstein equations, which themselves appear to prohibit the linear confinement-type potentials which could indicate a disordered gravitational phase. Our findings challenge the fidelity of the previous Euclidean lattice analyses. We confirm by direct calculation using a number of perturbation schemes and gauges that the next-to-leading order gravitoelectric correction to the rotation curve of a reasonable baryonic profile would be imperceptible. The `gravitoelectric flux collapse’ programme was also supported by using intragalactic lensing near a specific galactic baryon profile as a field strength heuristic. We recalculate this lensing effect, and conclude that it has been overstated by three orders of magnitude. As a by-product, our analysis suggests fresh approaches to (i) the fluid ball conjecture and (ii) gravitational energy localisation, both to be pursued in future work. In summary, whilst it may be interesting to consider the possibility of confinement-type effects in gravity, we may at least conclude here that confinement-type effects $\textit{cannot play any significant part}$ in explaining flat or rising galactic rotation curves without dark matter halos.

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W. Barker, M. Hobson and A. Lasenby
Tue, 21 Mar 23
9/68

Comments: 33 pages, 19 figures

Revisiting Puffy Dark Matter with Novel Insights: Partial Wave Analysis [CL]

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http://arxiv.org/abs/2303.11058


We present a comprehensive study on the self-interaction cross-section of puffy dark matter (DM) particles, which have a significant intrinsic size compared to their Compton wavelength. For such puffy DM self-interaction cross-section in the resonant and classical regimes, our study demonstrates the significance of the Yukawa potential and the necessity of partial wave analysis: (i) Due to the finite-size effect of puffy DM particles, the new Yukawa potential of puffy DM is found to enlarge the Born-effective regime for the self-interaction cross-section, compared with the point-like DM; (ii) Our partial wave analysis shows that depending on the value of the ratio between $R_{\chi}$ (radius of a puffy DM particle) and $1/m_{\phi}$ (force range), the three regimes (Born-effective, resonant and classical) for puffy DM self-interaction cross-section can be very different from the point-like DM; (iii) We find that to solve the small-scale anomalies via self-interacting puffy DM, the Born-effective and the resonant regimes exist for dwarf galaxies, while for the cluster and Milky Way galaxy the non-Born regime is necessary.

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W. Wang, W. Xu, J. Yang, et. al.
Tue, 21 Mar 23
35/68

Comments: 17page, 8figure

Compact stellar structures in Weyl geometric gravity [CL]

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http://arxiv.org/abs/2303.10339


We consider the structure and physical properties of specific classes of neutron, quark, and Bose-Einstein Condensate stars in the conformally invariant Weyl geometric gravity theory. The basic theory is derived from the simplest conformally invariant action, constructed, in Weyl geometry, from the square of the Weyl scalar, the strength of the Weyl vector, and a matter term, respectively. The action is linearized in the Weyl scalar by introducing an auxiliary scalar field. To keep the theory conformally invariant the trace condition is imposed on the matter energy-momentum tensor. The field equations are derived by varying the action with respect to the metric tensor, Weyl vector field and scalar field. By adopting a static spherically symmetric interior geometry, we obtain the field equations, describing the structure and properties of stellar objects in Weyl geometric gravity. The solutions of the field equations are obtained numerically, for different equations of state of the neutron and quark matter. More specifically, constant density stellar models, and models described by the stiff fluid, radiation fluid, quark bag model, and Bose-Einstein Condensate equations of state are explicitly constructed numerically in both general relativity and Weyl geometric gravity, thus allowing an in depth comparison between the predictions of these two gravitational theories. As a general result it turns out that for all the considered equations of state, Weyl geometric gravity stars are more massive than their general relativistic counterparts. As a possible astrophysical application of the obtained results we suggest that the recently observed neutron stars, with masses in the range of 2$M_{\odot}$ and 3$M_{\odot}$, respectively, could be in fact conformally invariant Weyl geometric neutron or quark stars.

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Z. Haghani and T. Harko
Tue, 21 Mar 23
36/68

Comments: 20 pages, 15 figures, accepted for publication in PRD

A machine learning and feature engineering approach for the prediction of the uncontrolled re-entry of space objects [CL]

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http://arxiv.org/abs/2303.10183


The continuously growing number of objects orbiting around the Earth is expected to be accompanied by an increasing frequency of objects re-entering the Earth’s atmosphere. Many of these re-entries will be uncontrolled, making their prediction challenging and subject to several uncertainties. Traditionally, re-entry predictions are based on the propagation of the object’s dynamics using state-of-the-art modelling techniques for the forces acting on the object. However, modelling errors, particularly related to the prediction of atmospheric drag may result in poor prediction accuracies. In this context, we explore the possibility to perform a paradigm shift, from a physics-based approach to a data-driven approach. To this aim, we present the development of a deep learning model for the re-entry prediction of uncontrolled objects in Low Earth Orbit (LEO). The model is based on a modified version of the Sequence-to-Sequence architecture and is trained on the average altitude profile as derived from a set of Two-Line Element (TLE) data of over 400 bodies. The novelty of the work consists in introducing in the deep learning model, alongside the average altitude, three new input features: a drag-like coefficient (B*), the average solar index, and the area-to-mass ratio of the object. The developed model is tested on a set of objects studied in the Inter-Agency Space Debris Coordination Committee (IADC) campaigns. The results show that the best performances are obtained on bodies characterised by the same drag-like coefficient and eccentricity distribution as the training set.

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F. Salmaso, M. Trisolini and C. Colombo
Tue, 21 Mar 23
43/68

Comments: N/A

Microlensing and multi-images problem of static spherical symmetric wormhole [CL]

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http://arxiv.org/abs/2303.11134


In this paper, we develop a framework to re-examine the weak lensing (including the microlensing) effects of the static spherical symmetric wormhole in terms of the radial equation of state $\eta=\frac{p_r}{\rho}$ (REoS). As for its application, we calculate its magnification, and event rate under this REoS, in which we show that the maximal value of magnification of the Ellis-Bronnikov wormhole is only related to the relative position and intrinsic angle, whose the maximal value is around five. For the event rate, our results indicate that one cannot distinguish the Eillis-Bronnikov wormhole and charged wormhole, but its order is much higher than the vacuum case, in which all these metrics belong to the static spherical symmetric wormhole metric. By calculating the lensing equation of the static spherical symmetric wormhole, we find an explicit formula between the maximal number of images of the wormhole and $\eta$. It shows that this relation is consistent with the classical wormhole, but the case for wormhole with quantum corrections is still mysterious. Our new method may shed new light on distinguishing the wormhole and blackhole via the event rate.

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K. Gao and L. Liu
Tue, 21 Mar 23
49/68

Comments: 19 pages, 7 figures, comments are welcome

Searching for continuous Gravitational Waves in the second data release of the International Pulsar Timing Array [CL]

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http://arxiv.org/abs/2303.10767


The International Pulsar Timing Array 2nd data release is the combination of datasets from worldwide collaborations. In this study, we search for continuous waves: gravitational wave signals produced by individual supermassive black hole binaries in the local universe. We consider binaries on circular orbits and neglect the evolution of orbital frequency over the observational span. We find no evidence for such signals and set sky averaged 95% upper limits on their amplitude h 95 . The most sensitive frequency is 10nHz with h 95 = 9.1 10-15 . We achieved the best upper limit to date at low and high frequencies of the PTA band thanks to improved effective cadence of observations. In our analysis, we have taken into account the recently discovered common red noise process, which has an impact at low frequencies. We also find that the peculiar noise features present in some pulsars data must be taken into account to reduce the false alarm. We show that using custom noise models is essential in searching for continuous gravitational wave signals and setting the upper limit.

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M. Falxa, S. Babak, P. Baker, et. al.
Tue, 21 Mar 23
52/68

Comments: N/A

Scaling anisotropy with stationary background field in the near-Sun solar wind turbulence [CL]

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http://arxiv.org/abs/2303.10810


The scaling of magnetic fluctuations provides crucial information for the understanding of solar wind turbulence. However, the observed magnetic fluctuations contain not only turbulence but also magnetic structures, leading to the violation of the time stationarity. This violation would conceal the true scaling and influence the determination of the sampling angle with respect to the local background magnetic field. Here, to investigate the scaling anisotropy, we utilize an easy but effective criterion $\phi<10^\circ$ to ensure the time stationarity of the magnetic field, where $\phi$ is the angle between the two averaged magnetic fields after cutting the interval into two halves. We study the scaling anisotropy using higher-order statistics of structure functions under the condition of stationarity for the near-Sun solar wind turbulence for the first time based on measurements obtained from Parker Solar Probe (PSP) at 0.17 au. We find that the scaling indices $\xi$ of magnetic field show a linear dependence on the order $p$ close to $\xi(p)=p/4$. The multifractal scaling of magnetic-trace structure functions becomes monoscaling close to $\xi(p)=p/3$ with the local magnetic field perpendicular to the sampling direction and close to $\xi(p)=p/4$ with the local magnetic field parallel to the sampling direction when measured with the stationary background magnetic field. The scaling of velocity-trace structure functions has similar but less significant changes. The near-Sun solar wind turbulence displays different scaling anisotropies with the near-Earth solar wind turbulence, suggesting the evolution of the nonlinear interaction process during the solar wind expansion.

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H. Wu, J. He, S. Huang, et. al.
Tue, 21 Mar 23
56/68

Comments: 15 pages, 5 figures, accepted by ApJ

Cross Sections of the $^{83}$Rb(p,$γ)^{84}$Sr and $^{84}$Kr(p,$γ)^{85}$Rb Reactions at Energies Characteristic of the Astrophysical $γ$ Process [CL]

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http://arxiv.org/abs/2303.10282


We have measured the cross section of the $^{83}$Rb(p,$\gamma)^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of $^{83}$Rb at incident energies of 2.4 and $2.7 A$ MeV. Prior to the radioactive beam measurement, the $^{84}$Kr(p,$\gamma)^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of $^{84}$Kr at an incident energy of $2.7 A$ MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the $\gamma$ process in supernovae. The central values of the measured partial cross sections of both reactions were found to be $0.17-0.42$ times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the $p$ nucleus $^{84}$Sr, caused by the reduced rate of the $^{84}$Sr($\gamma$,p)$^{83}$Rb reaction derived from the present measurement.

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M. Williams, B. Davids, G. Lotay, et. al.
Tue, 21 Mar 23
61/68

Comments: 11 pages, 11 figures. arXiv admin note: text overlap with arXiv:2109.06775

Radial Oscillations in Neutron Stars with Delta Baryons [CL]

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http://arxiv.org/abs/2303.11006


We investigate the effect of $\Delta$ baryons on the radial oscillations of neutron and hyperon stars, employing the density-dependent relativistic mean-field model. The spin-$3/2$ baryons are described by the Rarita-Schwinger Lagrangian density. The baryon-meson coupling constants for the spin-3/2 decuplet and the spin-1/2 baryonic octet are calculated using a unified approach relying on the fact that the Yukawa couplings present in the Lagrangian density of the mean-field models must be invariant under the SU(3) and SU(6) group transformations. We calculate the 20 lowest eigenfrequencies and corresponding oscillation functions of $\Delta$-admixtured nuclear (N$\Delta$) and hyperonic matter (NH$\Delta$) by solving the Sturm-Liouville boundary value problem and also verifying its validity. We see that the lowest mode frequencies for N+$\Delta$ and N+H EoSs are higher as compared to the pure nucleonic matter because of the delta and hyperonic admixtures. Furthermore, the separation between consecutive modes increases with the addition of hyperons and $\Delta$s.

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I. Rather, K. Marquez, G. Panotopoulos, et. al.
Tue, 21 Mar 23
62/68

Comments: 11 pages, 8 figures, 3 tables, will be submitted to the journal in few days to allow for the comments

Time behaviour of Hubble parameter by torsion [CL]

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http://arxiv.org/abs/2303.10356


Consequences of the consistent exact solution of Einstein-Cartan equation on the time dependence of Hubble parameter is discussed. The torsion leads to a space and time dependent expansion parameter which results into nontrivial windows of Hubble parameter between diverging behaviour. Only one window shows a period of decreasing followed by increasing time dependence. Provided a known cosmological constant and the present values of Hubble and deceleration parameter this changing time can be given in the past as well as the ending time of the windows or universe. From the metric with torsion outside matter it is seen that torsion can feign dark matter.

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K. Morawetz
Tue, 21 Mar 23
65/68

Comments: N/A

Ultraviolet Sensitivity in Higgs-Starobinsky Inflation [CL]

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http://arxiv.org/abs/2303.09866


The general scalar-tensor theory that includes all the dimension-four terms has parameter regions that can produce successful inflation consistent with cosmological observations. This theory is in fact the same as the Higgs-Starobinsky inflation, when the scalar is identified with the Standard Model Higgs boson. We consider possible dimension-six operators constructed from non-derivative terms of the scalar field and the Ricci scalar as perturbations. We investigate how much suppression is required for these operators to avoid disrupting the successful inflationary predictions. To ensure viable cosmological predictions, the suppression scale for the sixth power of the scalar should be as high as the Planck scale. For the other terms, much smaller scales are sufficient.

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S. Lee, T. Modak, K. Oda, et. al.
Mon, 20 Mar 23
29/51

Comments: 23 pages, 12 figures

Holographic dark energy satisfying the energy conditions in Lovelock gravity [CL]

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http://arxiv.org/abs/2303.09563


In this paper, we show that the holographic dark energy density hides in the solutions of Lovelock gravity for black holes. Using the obtained mass and temperature we find density equations. We propose a physical interpretation of the rescaled Lovelock couplings as a topological mass that describes the Lovelock branch. In addition to this, we present new solutions that satisfy the energy conditions according to the Lovelock coupling and the horizon curvatures. This work can be extended to the equation of the state {\omega}{{\Lambda}} of dark energy in third-order Lovelock gravity. We show that the value “-1” represents a stable equilibrium of {\omega}{{\Lambda}}.

Read this paper on arXiv…

M. Bousder, E. Salmani, A. Fatimy, et. al.
Mon, 20 Mar 23
34/51

Comments: 16 pages, 2 figures

Secondary School Students observe Venus with NASA Infrared Telescope Facility (IRTF) [CL]

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http://arxiv.org/abs/2303.10010


Astronomy and astrophysics are regarded as highly motivating topics for students in primary and secondary schools, and they have been a recurrent and effective resource to inspire passion about science. In fact, during the last years we have witnessed a boost of facilities providing small robotic telescopes for teachers and students to remotely undertake their own observing projects. A step forward is presented here, where we describe the experience of secondary school students attending professional observations of Venus at NASA’s Infrared Telescope Facility (IRTF) and, in a second observing run, conducting the observations by themselves. In addition to quickly mastering the basic operation of the control software for the SpeX instrument, the students successfully performed different types of data acquisition, including drift scan imaging.

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J. Peralta, J. Prieto, P. Orozco-Sáenz, et. al.
Mon, 20 Mar 23
40/51

Comments: 4 pages, 1 figure

Earth tomography with supernova neutrinos at future neutrino detectors [CL]

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http://arxiv.org/abs/2303.09369


Earth neutrino tomography is a realistic possibility with current and future neutrino detectors, complementary to geophysics methods. The two main approaches are based on either partial absorption of the neutrino flux as it propagates through the Earth (at energies about a few TeV) or on coherent Earth matter effects affecting the neutrino oscillations pattern (at energies below a few tens of GeV). In this work, we consider the latter approach focusing on supernova neutrinos with tens of MeV. Whereas at GeV energies, Earth matter effects are driven by the atmospheric mass-squared difference, at energies below $\sim 100$~MeV, it is the solar mass-squared difference what controls them. Unlike solar neutrinos, which suffer from significant weakening of the contribution to the oscillatory effect from remote structures due to the neutrino energy reconstruction capabilities of detectors, supernova neutrinos can have higher energies and thus, can better probe the Earth’s interior. We shall revisit this possibility, using the most recent neutrino oscillation parameters and up-to-date supernova neutrino spectra. The capabilities of future neutrino detectors, such as DUNE, Hyper-Kamiokande and JUNO are presented, including the impact of the energy resolution and other factors. Assuming a supernova burst at 10~kpc, we show that the average Earth’s core density could be determined within $\lesssim 10\%$ at $1\sigma$ confidence level, being Hyper-Kamiokande, with its largest mass, the most promising detector to achieve this goal.

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R. Hajjar, O. Mena and S. Palomares-Ruiz
Mon, 20 Mar 23
50/51

Comments: 25 pages, 9 figures

Probing Cosmological Particle Production and Pairwise Hotspots with Deep Neural Networks [CL]

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http://arxiv.org/abs/2303.08869


Particles with masses much larger than the inflationary Hubble scale, $H_I$, can be pair-produced non-adiabatically during inflation. Due to their large masses, the produced particles modify the curvature perturbation around their locations. These localized perturbations eventually give rise to localized signatures on the Cosmic Microwave Background (CMB), in particular, pairwise hotspots (PHS). In this work, we show that Convolutional Neural Networks (CNN) provide a powerful tool for identifying PHS on the CMB. While for a given hotspot profile a traditional Matched Filter Analysis is known to be optimal, a Neural Network learns to effectively detect the large variety of shapes that can arise in realistic models of particle production. Considering an idealized situation where the dominant background to the PHS signal comes from the standard CMB fluctuations, we show that a CNN can isolate the PHS with $\mathcal{O}(10)\%$ efficiency even if the hotspot temperature is $\mathcal{O}(10)$ times smaller than the average CMB fluctuations. Overall, the CNN search is sensitive to heavy particle masses $M_0/H_I=\mathcal{O}(200)$, and constitutes one of the unique probes of very high energy particle physics.

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T. Kim, J. Kim, S. Kumar, et. al.
Fri, 17 Mar 23
1/67

Comments: N/A

The EUCLID NISP grisms flight models performance [CL]

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http://arxiv.org/abs/2303.09130


ESA EUCLID mission will be launched in 2020 to understand the nature of the dark energy responsible of the accelerated expansion of the Universe and to map the geometry of the dark matter. The map will investigate the distanceredshift relationship and the evolution of cosmic structures thanks to two instruments: the NISP and the VIS. The NISP (Near Infrared Spectro-Photometer) is operating in the near-IR spectral range (0.9-2$\mu$m) with two observing modes: the photometric mode for the acquisition of images with broad band filters, and the spectroscopic mode for the acquisition of slitless dispersed images on the detectors. The spectroscopic mode uses four low resolution grisms to cover two spectral ranges: three ”red” grisms for 1250-1850nm range, with three different orientations, and one ”blue” grism for 920- 1300nm range. The NISP grisms are complex optical components combining four main optical functions: a grism function (dispersion without beam deviation of the first diffracted order) done by the grating on the prism hypotenuse, a spectral filter done by a multilayer filter deposited on the first face of the prism to select the spectral bandpass, a focus function done by the curved filter face of the prism (curvature radius of 10m) and a spectral wavefront correction done by the grating which grooves paths are nor parallel, neither straight. The development of these components have been started since 10 years at the Laboratoire d’Astrophysique de Marseille (LAM) and was linked to the project phases: prototypes have been developed to demonstrate the feasibility, then engineering and qualification models to validate the optical and mechanical performance of the component, finally the flight models have been manufactured and tested and will be installed on NISP instrument. In this paper, we present the optical performance of the four EUCLID NISP grisms flight models characterized at LAM: wavefront error, spectral transmission and grating groove profiles. The test devices and the methods developed for the characterization of these specific optical components are described. The analysis of the test results have shown that the grisms flight models for NISP are within specifications with an efficiency better than 70% on the spectral bandpass and a wavefront error on surfaces better than 30nm RMS. The components have withstood vibration qualification level up to 11.6g RMS in random test and vacuum cryogenics test down to 130K with measurement of optical quality in transmission. The EUCLID grisms flight models have been delivered to NISP project in November 2017 after the test campaign done at LAM that has demonstrated the compliance to the specifications.

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A. Costille, A. Caillat, C. Rossin, et. al.
Fri, 17 Mar 23
5/67

Comments: N/A

Correlation of structure growth index with current cosmic acceleration: constraints on dark energy models [CL]

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http://arxiv.org/abs/2303.09492


We study dynamical dark energy models within Einstein’s theory by means of matter perturbations and the growth index $\gamma$. Within four-dimensional General Relativity, we assume that dark energy does not cluster, and we adopt a linear ansatz for the growth index to investigate its impact on the deceleration parameter, $q$, and on the dark energy equation-of-state parameter, $w$. Following this approach, we identify a relationship between $q_0$ (today’s value of $q$) and $\gamma$, which to the best of our knowledge is new. For $w(z)$, we find that in most of the cases considered it crosses the -1 line (quintom) ending at a present day value $w_0 > -1$. Furthermore, we show that an analytic expression for $w(z)$ may be obtained in the form of order (4,4) (or higher) Pad{\’e} parameterizations.

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G. Panotopoulos, G. Barnert and L. Campusano
Fri, 17 Mar 23
8/67

Comments: 13 pages, 3 figures, to be published in IJMPD

Novel exact ultra-compact and ultra-sparse hairy black holes emanating from regular and phantom scalar fields [CL]

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http://arxiv.org/abs/2303.09116


In the framework of a simple gravitational theory that contains a scalar field minimally coupled to gravity, we investigate the emergence of analytic black-hole solutions with non-trivial scalar hair of secondary type. Although it is possible for one to obtain asymptotically (A)dS solutions using our setup, in the context of the present work, we are solely interested in asymptotically flat solutions. At first, we study the properties of static and spherically symmetric black-hole solutions emanating from both regular and phantom scalar fields. We find that the regular-scalar-field-induced solutions are solutions describing ultra-compact black holes, while the phantom scalar fields generate ultra-sparse black-hole solutions. The latter are black holes that can be potentially of very low density since, contrary to ultra-compact ones, their horizon radius is always greater than the horizon radius of the corresponding Schwarzschild black hole of the same mass. Then, we generalize the above static solutions to slowly rotating ones and compute their angular velocities explicitly. Finally, the study of the axial perturbations of the derived solutions takes place, in which we show that there is always a region in the parameter space of the free parameters of our theory that allows the existence of both ultra-compact and ultra-sparse black holes.

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A. Bakopoulos and T. Nakas
Fri, 17 Mar 23
12/67

Comments: 22 pages, 6 figures

Putting all the X in one basket: Updated X-ray constraints on sub-GeV Dark Matter [CL]

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http://arxiv.org/abs/2303.08854


Sub-GeV dark matter particles can annihilate or decay producing e^\pm pairs which upscatter the low-energy photon fields in the Galaxy and generate an X-ray emission (via the Inverse Compton effect). Using X-ray data from Xmm-Newton, Integral, NuStar and Suzaku, we derive new constraints on this class of dark matter (DM). In the annihilation case, our new bounds are the strongest available for DM masses above 180 MeV, reaching <sigma v> < 10^-28 cm^3/s for m_DM ~ 1 GeV. In the decay case, our bounds are the strongest to date essentially in the whole considered mass range, constraining tau > 10^28 s for m_DM ~ 1 GeV and improving by up to 3 orders of magnitude upon existing limits.

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M. Cirelli, N. Fornengo, J. Koechler, et. al.
Fri, 17 Mar 23
32/67

Comments: 16 pages, 9 figures

M$^5$ — Mars Magnetospheric Multipoint Measurement Mission: A multi-spacecraft plasma physics mission to Mars [CL]

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http://arxiv.org/abs/2303.09502


Mars, lacking an intrinsic dynamo, is an ideal laboratory to comparatively study induced magnetospheres, which can be found in other terrestrial bodies as well as comets. Additionally, Mars is of particular interest to further exploration due to its loss of habitability by atmospheric escape and possible future human exploration. In this context, we propose the Mars Magnetospheric Multipoint Measurement Mission (M$^5$), a multi-spacecraft mission to study the dynamics and energy transport of the Martian induced magnetosphere comprehensively. Particular focus is dedicated to the largely unexplored magnetotail region, where signatures of magnetic reconnection have been found. Furthermore, a reliable knowledge of the upstream solar wind conditions is needed to study the dynamics of the Martian magnetosphere, especially the different dayside boundary regions but also for energy transport phenomena like the current system and plasma waves. This will aid the study of atmospheric escape processes of planets with induced magnetospheres. In order to resolve the three-dimensional structures varying both in time and space, multi-point measurements are required. Thus, M$^5$ is a five spacecraft mission, with one solar wind monitor orbiting Mars in a circular orbit at 5 Martian radii, and four smaller spacecraft in a tetrahedral configuration orbiting Mars in an elliptical orbit, spanning the far magnetotail up to 6 Mars radii with a periapsis within the Martian magnetosphere of 1.8 Mars radii. We not only present a detailed assessment of the scientific need for such a mission but also show the resulting mission and spacecraft design taking into account all aspects of the mission requirements and constraints such as mass, power, and link budgets. This mission concept was developed during the Alpbach Summer School 2022.

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C. Larkin, V. Lundén, L. Schulz, et. al.
Fri, 17 Mar 23
44/67

Comments: 16 pages, 9 figures. Submitted to Advances in Space Research

Swampland criteria for rescaled Einstein-Hilbert gravity with string corrections [CL]

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http://arxiv.org/abs/2301.08126


In this work we examine the Swampland criteria for a specific class of rescaled $f(R)$ gravitational models, that are capable of unifying the primordial era of the Universe with the late-time era with the inclusion of string corrections. In particular, we develop separately the theoretical framework of Gauss-Bonnet and Chern-Simons theories considering that, the rescale parameter is constrained to reside in the area $0<\alpha<1$. As showcased, in the context of the aforementioned theories, a viable inflationary phenomenology consistent with the latest Planck data can be obtained for both cases for a wide variety of values. The Swampland criteria which where examined are satisfied, not necessarily simultaneously, for small values of the rescale parameter, which is in agreement with the case of a canonical scalar field with absent string corrective terms. The Gauss-Bonnet model is also further constrained, in order to obtain a propagation velocity of tensor perturbations which coincides with that of light, according to the recent observations from the GW170817. As a result of this assumption the degrees of freedom of the theory are reduced. An interesting feature which arises from the overall phenomenology is that, due to the inclusion of string corrections the tensor spectral index of primordial perturbations is now capable of obtaining a positive value which is not possible in the case of the canonical scalar field. Last but not least, the power-law model which is known to be incompatible with observations is now rendered viable by including a parity violating term and as showcased, it satisfies the Swampland criteria as well.

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A. Gitsis, K. Revis, S. Venikoudis, et. al.
Fri, 20 Jan 23
4/72

Comments: N/A

Action-Angle formalism for extreme mass ratio inspirals in Kerr spacetime [CL]

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http://arxiv.org/abs/2301.08150


We introduce an action-angle formalism for bounded geodesic motion in Kerr black hole spacetime using canonical perturbation theory. Namely, we employ a Lie series technique to produce a series of canonical transformations on a Hamiltonian function describing geodesic motion in Kerr background written in Boyer-Lindquist coordinates to a Hamiltonian system written in action-angle variables. This technique allows us to produce a closed-form invertible relation between the Boyer-Lindquist variables and the action-angle ones, while it generates in analytical closed form all the characteristic functions of the system as well. The expressed in the action-angle variable Hamiltonian system is employed to model an extreme mass ratio inspiral (EMRI), i.e. a binary system where a stellar compact object inspirals into a supermassive black hole due to gravitational radiation reaction. We consider the adiabatic evolution of an EMRI, for which the energy and angular momentum fluxes are computed by solving the Teukolsky equation in the frequency domain. To achieve this a new Teukolsky equation solver code was developed.

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M. Kerachian, L. Polcar, V. Skoupý, et. al.
Fri, 20 Jan 23
5/72

Comments: 20 pages, 7 figures, 5 tables, includes CPKerrGeodesics (a Mathematica package) as supplemental material

Optical ultra-stable optical clock cavities as resonant mass gravitational wave detectors in search for new physics [CL]

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http://arxiv.org/abs/2301.08200


We propose to use table-top-size ultra-stable optical cavities from the state-of-the-art optical atomic clocks as bar gravitational wave detectors for the frequencies higher than 2 kHz. We show that 2-20 kHz range of gravitational waves’ spectrum can be accessed with instruments below 2 meters in size. The proposed cavities’ materials and properties are being within the present-day technology grasp. The ultra-stable optical cavities allow detecting not only predicted gravitational wave signals from such sources as binary neutron star mergers and post-mergers, subsolar-mass primordial black-hole mergers, and collapsing stellar cores, but can reach new physics beyond standard model looking for ultralight bosons such as QCD axions and axion-like particles formed through black hole superradiance.

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M. Narożnik, M. Bober and M. Zawada
Fri, 20 Jan 23
13/72

Comments: N/A

The Scale of Supersymmetry Breaking and the Dark Dimension [CL]

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http://arxiv.org/abs/2301.07719


We argue for a relation between the supersymmetry breaking scale and the measured value of the dark energy density $\Lambda$. We derive it by combining two quantum gravity consistency swampland constraints, which tie the dark energy density $\Lambda$ and the gravitino mass $M_{3/2}$, respectively, to the mass scale of a light Kaluza-Klein tower and, therefore, to the UV cut-off of the effective theory. Whereas the constraint on $\Lambda$ has recently led to the Dark Dimension scenario, with a prediction of a single mesoscopic extra dimension of the micron size, we use the constraint on $M_{3/2}$ to infer the implications of such a scenario for the scale of supersymmetry breaking. We find that a natural scale for supersymmetry signatures is $M={\cal O}\left(\Lambda^{1/8}\right)={\cal O}({\rm TeV})$. This mass scale is within reach of LHC and of the next generation of hadron colliders. Finally, we discuss possible string theory and effective supergravity realizations of the Dark Dimension scenario with broken supersymmetry.

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L. Anchordoqui, I. Antoniadis, N. Cribiori, et. al.
Fri, 20 Jan 23
17/72

Comments: 18 pages

Bayesian inference of neutron-star observables based on effective nuclear interactions [CL]

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http://arxiv.org/abs/2301.07904


Based on the Skyrme-Hartree-Fock model (SHF) as well as its extension (the Korea-IBS-Daegu-SKKU (KIDS) model) and the relativistic mean-field (RMF) model, we have studied the constraints on the parameters of the nuclear matter equation of state (EOS) from adopted astrophysical observables using a Bayesian approach. While the masses and radii of neutron stars generally favors a stiff isoscalar EOS and a relatively soft nuclear symmetry energy, model dependence on the constraints is observed and mostly originates from the incorporation of higher-order EOS parameters and difference between relativistic and non-relativistic models. At twice saturation density, the value of the symmetry energy is constrained to be $48^{+15}{-11}$ MeV in the standard SHF model, $48^{+8}{-15}$ MeV in the KIDS model, and $48^{+5}_{-6}$ MeV in the RMF model, around their maximum {\it a posteriori} values within $68\%$ confidence intervals. Our study helps to obtain a robust constraint on nuclear matter EOS, and meanwhile, to understand the model dependence of the results.

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J. Zhou, J. Xu and P. Papakonstantinou
Fri, 20 Jan 23
19/72

Comments: 15 pages, 8 figures

An Analytic Approach to Light Dark Matter Propagation [CL]

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http://arxiv.org/abs/2301.07728


If dark matter interacts too strongly with nuclei, it could be slowed to undetectable speeds in Earth’s crust or atmosphere before ever reaching a detector. For sub-GeV dark matter, analytic approximations appropriate for heavier dark matter fail, necessitating the use of computationally expensive simulations. We present a new method of modeling attenuation of light dark matter in the Earth, based on the approximation that the scattering is isotropic in the lab frame. We show that this approach agrees well with Monte Carlo results, and can be much faster when the number of scatterings becomes large, as the runtime for Monte Carlo methods increases exponentially with cross section. We use this method to model attenuation for sub-dominant dark matter–that is, particles that make up a small fraction of the dark matter density–and show that previous work on sub-dominant dark matter overestimates the sensitivity of direct detection experiments.

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C. Cappiello
Fri, 20 Jan 23
35/72

Comments: 5 pages, 4 figures

Spanning the full range of neutron star properties within a microscopic description [CL]

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http://arxiv.org/abs/2301.08169


The high density behavior of nuclear matter is analyzed within a relativistic mean field description with non-linear meson interactions. To assess the model parameters and their output, a Bayesian inference technique is used. The Bayesian setup is limited only by a few nuclear saturation properties, the neutron star maximum mass larger than 2 M$\odot$, and the low-density pure neutron matter equation of state (EOS) produced by an accurate N$^3$LO calculation in chiral effective field theory. Depending on the strength of the non-linear scalar vector field contribution, we have found three distinct classes of EOSs, each one correlated to different star properties distributions. If the non-linear vector field contribution is absent, the gravitational maximum mass and the sound velocity at high densities are the greatest. However, it also gives the smallest speed of sound at densities below three times saturation density. On the other hand, models with the strongest non-linear vector field contribution, predict the largest radii and tidal deformabilities for 1.4 M$\odot$ stars, together with the smallest mass for the onset of the nucleonic direct Urca processes and the smallest central baryonic densities for the maximum mass configuration. These models have the largest speed of sound below three times saturation density, but the smallest at high densities, in particular, above four times saturation density the speed of sound decreases approaching approximately $\sqrt{0.4}c$ at the center of the maximum mass star. On the contrary, a weak non-linear vector contribution gives a monotonically increasing speed of sound. A 2.75 M$_\odot$ NS maximum mass was obtained in the tail of the posterior with a weak non-linear vector field interaction. This indicates that the secondary object in GW190814 could also be an NS.

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T. Malik, M. Ferreira and C. Providência
Fri, 20 Jan 23
40/72

Comments: (Submitted to PRD) 14 pages, 13 figures, supplemental material

Continuous Spectrum on Cosmological Collider [CL]

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http://arxiv.org/abs/2301.07920


We study the effects of a massive field with a continuous spectrum (continuum isocurvaton) on the inflationary bispectrum in the squeezed limit. As a concrete example, we extend the quasi-single field inflation model to include a continuum isocurvaton with a well-motivated spectral density from extra dimensions and focus on a contribution to the bispectrum with a single continuum isocurvaton exchange. In contrast to the usual case without the continuous spectrum, the amplitude of the bispectrum has a damping feature in the deep squeezed limit, which can be strong evidence for the continuous spectrum.

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S. Aoki
Fri, 20 Jan 23
45/72

Comments: 23 pages, 3 figures

Constraining fundamental parameters in modified gravity using Gaia-DR2 massive white dwarf observation [CL]

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http://arxiv.org/abs/2301.07645


Various experiments and observations have led researchers to suggest different bounds on fundamental constants like the fine-structure constant and the proton-to-electron mass ratio. These bounds differ mostly due to the energy scale of the systems where the experiments are performed. In this article, we obtain bounds on these parameters in the modified gravity context using the Gaia-DR2 massive white dwarf data and show that the bounds alter as the gravity theory changes. This exploration not only indicates strong support for non-negligible influences of modified gravity in astrophysical scenarios in high-density regimes but also reveals that the bounds on fundamental parameters can be much stronger under alternate gravity theories.

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S. Kalita and A. Uniyal
Fri, 20 Jan 23
57/72

Comments: 6 pages with 3 figures; comments welcome

On geometrical interpretation of alignment phenomenon [CL]

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http://arxiv.org/abs/2301.07975


The observed alignment of spots in the x-ray films in cosmic ray emulsion experiments is analyzed and interpreted in the framework of geometrical approach. It is shown that the high degree of alignment can appear partly due to the selection procedure of most energetic particles itself and the threshold on the energy deposition together with the transverse momentum conservation.

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I. Lokhtin, A. Nikolskii and A. Snigirev
Fri, 20 Jan 23
58/72

Comments: 6 pages, 5 figures

Intrinsic limits on the detection of the anisotropies of the Stochastic Gravitational Wave Background [CL]

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http://arxiv.org/abs/2301.08074


For any given network of detectors, and for any given integration time, even in the idealized limit of negligible instrumental noise, the intrinsic time variation of the isotropic component of the Stochastic Gravitational Wave Background (SGWB) induces a limit on how accurately the anisotropies in the SGWB can be measured. We show here how this sample limit can be calculated and apply this to three separate configurations of ground-based detectors placed at existing and planned sites. Our results show that in the idealized, best-case scenario individual multipoles of the anisotropies at $\ell \leq 8$ can only be measured to $\sim 10^{-5} – 10^{-4}$ level over 5 years of observation as a fraction of the isotropic component. As the sensitivity improves as the square root of the observation time, this poses a very serious challenge for the measurement of the anisotropies of SGWB of cosmological origin, even in the case of idealised detectors with arbitrarily low instrumental noise.

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G. Mentasti, C. Contaldi and M. Peloso
Fri, 20 Jan 23
61/72

Comments: 5 pages, 2 figures

Robust Chauvenet Rejection: Powerful, but Easy to Use Outlier Detection for Heavily Contaminated Data Sets [CL]

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http://arxiv.org/abs/2301.07838


In Maples et al. (2018) we introduced Robust Chauvenet Outlier Rejection, or RCR, a novel outlier rejection technique that evolves Chauvenet’s Criterion by sequentially applying different measures of central tendency and empirically determining the rejective sigma value. RCR is especially powerful for cleaning heavily-contaminated samples, and unlike other methods such as sigma clipping, it manages to be both accurate and precise when characterizing the underlying uncontaminated distributions of data sets, by using decreasingly robust but increasingly precise statistics in sequence. For this work, we present RCR from a software standpoint, newly implemented as a Python package while maintaining the speed of the C++ original. RCR has been well-tested, calibrated and simulated, and it can be used for both one-dimensional outlier rejection and $n$-dimensional model-fitting, with or without weighted data. RCR is free to use for academic and non-commercial purposes, and the code, documentation and accompanying web calculator can be found and easily used online at https://github.com/nickk124/RCR

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N. Konz and D. Reichart
Fri, 20 Jan 23
69/72

Comments: 10 pages, 6 figures, pre-print version. This paper introduces a Python library for the algorithm introduced in arXiv:1807.05276

Inferring the rate of technosignatures from sixty years of nondetection [CL]

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http://arxiv.org/abs/2301.07165


For about the last 60 years the search for extraterrestrial intelligence has been monitoring the sky for evidence of remotely detectable technological life beyond Earth, with no positive results to date. While the lack of detection can be attributed to the highly incomplete sampling of the search space, technological emissions may be actually rare enough that we are living in a time when none cross the Earth. This possibility has been considered in the past, but not to quantitatively assess its consequences on the galactic population of technoemissions. Here we derive the likelihood of the Earth not being crossed by signals for at least 60 years to infer upper bounds on their rate of emission. We found less than about one to five emissions per century generated from the Milky Way (95 % credible level), implying optimistic waiting times until the next crossing event of no less than 60 to 1,800 years with a 50 % probability. A significant fraction of highly directional signals increases the emission rates upper bounds, but without systematically changing the waiting time. Our results provide a benchmark for assessing the lack of detection and may serve as a basis to form optimal strategies for the search for extraterrestrial intelligence.

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C. Grimaldi
Thu, 19 Jan 23
12/100

Comments: 8 pages, 4 figures

The mass of charged pions in neutron star matter [CL]

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http://arxiv.org/abs/2301.07226


We examine the behavior of charged pions in neutron-rich matter using heavy-baryon chiral perturbation theory. This study is motivated by the prospect that pions, or pion-like, excitations, may be relevant in neutron-rich matter encountered in core-collapse supernovae and neutron star mergers. We find, as previously expected, that the $\pi^-$ mass increases with density and precludes s-wave condensation, and the mass of the $\pi^+$ mode decreases with increasing density. The energy difference between neutrons and protons in neutron-rich matter related to the nuclear symmetry energy alters the power counting. It enhances higher-order contributions to the pion self-energy. Previously unimportant but attractive diagrams are now enhanced. The net effect of this is the appearance of a new collective mode with the quantum numbers of the $\pi^+$, and a pronounced reduction of the $\pi^+$ mass.

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B. Fore, N. Kaiser, S. Reddy, et. al.
Thu, 19 Jan 23
22/100

Comments: 13 pages, 4 figures, 1 appendix

Chiral phonons as dark matter detectors [CL]

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http://arxiv.org/abs/2301.07617


We propose a method for detecting light dark matter particles via their creation of chiral phonons in standard model matter. We suggest metal-organic frameworks (MOFs) as candidate materials for such detectors, as their structural flexibility yields low-energy chiral phonons with magnetic moments that are large enough to detect using sensitive magnetometers, and their anisotropy leads to directional sensitivity, which mitigates background contamination. To demonstrate our proposal, we calculate the phononic structure of the MOF InF$_3$($4,4’$-bipyridine), and show that it has highly chiral acoustic phonons. Detection of such chiral phonons via their magnetic moments would dramatically lower the excitation energy threshold to the energy of a single phonon. We show that single phonon detection in a MOF would extend detector reach ten or more orders of magnitude below current limits, enabling exploration of a multitude of as-yet-unprobed dark matter candidates.

Read this paper on arXiv…

C. Romao, R. Catena, N. Spaldin, et. al.
Thu, 19 Jan 23
24/100

Comments: 11 pages, 4 figures

Can we discern microlensed gravitational-wave signals from the signal of precessing compact binary mergers? [CL]

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http://arxiv.org/abs/2301.07253


Microlensed gravitational waves (GWs) are likely observable by recognizing the signature of interference caused by $\sim!\mathcal{O}(10\textrm{–}100)~\textrm{ms}$ time delays between multiple lensed signals. However, the shape of the anticipated microlensed GW signals might be confused with the modulation appearing in the waveform of GWs from precessing compact binary mergers. Their morphological similarity may be an obstacle to template-based searches to correctly identifying the origin of observed GWs and it seamlessly raises a fundamental question, \emph{can we discern microlensed GW signals from the signal of precessing compact binary mergers?} We discuss the feasibility of distinguishing those GWs via examining simulated GW signals with and without the presence of noise. We find that it is certainly possible if we compare signal-to-noise ratios (SNRs) computed with templates of different hypotheses for a given target signal. We show that proper parameter estimation for lensed GWs enables us to identify the targets of interest by focusing on a half number of assumptions for the target signal than the SNR-based test.

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K. Kim and A. Liu
Thu, 19 Jan 23
31/100

Comments: 8 pages, 4 figures, 2 tables, submitted to PRL

SFQEDtoolkit: a high-performance library for the accurate modeling of strong-field QED processes in PIC and Monte Carlo codes [CL]

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http://arxiv.org/abs/2301.07684


Strong-field QED (SFQED) processes are central in determining the dynamics of particles and plasmas in extreme electromagnetic fields such as those present in the vicinity of compact astrophysical objects or generated with ultraintense lasers. SFQEDtoolkit is an open source library designed to allow users for a straightforward implementation of SFQED processes in existing particle-in-cell (PIC) and Monte Carlo codes. Through advanced function approximation techniques, high-energy photon emission and electron-positron pair creation probability rates and energy distributions are calculated within the locally-constant-field approximation (LCFA) as well as with more advanced models [Phys. Rev. A 99, 022125 (2019)]. SFQEDtoolkit is designed to provide users with high-performance and high-accuracy, and neat examples showing its usage are provided. In the near future, SFQEDtoolkit will be enriched to model the angular distribution of the generated particles, i.e., beyond the commonly employed collinear emission approximation, as well as to model spin and polarization dependent SFQED processes. Notably, the generality and flexibility of the presented function approximation approach makes it suitable to be employed in other areas of physics, chemistry and computer science.

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S. Montefiori and M. Tamburini
Thu, 19 Jan 23
52/100

Comments: 31 pages, 7 figures. Repository with the associated open-source code available on github this https URL

Turning point principle for stability of viscous gaseous stars [CL]

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http://arxiv.org/abs/2301.07328


We consider stability of non-rotating viscous gaseous stars modeled by the Navier-Stokes-Poisson system. Under general assumptions on the equations of states, we proved that the number of unstable modes for the linearized Navier-Stokes-Poisson system equals that of the linearized Euler-Poisson system modeling inviscid gaseous stars. In particular, the turning point principle holds true for non-rotating stars with or without viscosity. That is, the transition of stability only occurs at the extrema of the total mass and the number of unstable modes is determined by the mass-radius curve. For the proof, we establish an infinite dimensional Kelvin-Tait-Chetaev theorem for a class of linear second order PDEs with dissipation. Moreover, we prove that linear stability implies nonlinear asymptotic stability and linear instability implies nonlinear instability for Navier-Stokes-Poisson system.

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M. Cheng, Z. Lin and Y. Wang
Thu, 19 Jan 23
54/100

Comments: N/A

Resurfaced 1964 VRT video interview of Georges Lemaître [CL]

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http://arxiv.org/abs/2301.07198


On December 31 2022, the Vlaamse Radio- en Televisieomroeporganisatie (VRT), the national public-service broadcaster for the Flemish Community of Belgium, recovered a video recording of a 1964 interview of Georges Lema\^itre. Up until now, that footage was thought to have been lost. This footage represents a unique insight into the views of the physicist often coined as the “father of the Big Bang”. The interview was conducted in French and is available online with Flemish subtitles. In an effort to make this treasure broadly available, we provide in this paper some brief context, an English translation of the interview as well as the French transcript for reference.

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S. Gontcho, J. Eluo and P. Gabor
Thu, 19 Jan 23
56/100

Comments: VRT article linking the recovered footage: this https URL

Parametric resonance in abelian and non-abelian gauge fields via space-time oscillations [CL]

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http://arxiv.org/abs/2301.07456


We study the evolution of abelian electromagnetic as well as non-abelian gauge fields, in the presence of space-time oscillations. In the non-abelian case, we consider linear approximation, to analyse the time evolution of the field modes. In both abelian and non-abelian, the mode equations, show the presence of the same parametric resonant spatial modes. The large growth of resonant modes induces large fluctuations in physical observables including those that break the $CP-$symmetry. We also evolve small random fluctuations of fields, using numerical simulations in $2+1$ dimensions. These simulations help study non-linear effects $vs$ the gauge coupling, in the non-abelian case. Our results show that there is an increase in energy density with the coupling, at late times. These results suggest that gravitational waves may excite non-abelian gauge fields more efficiently than electromagnetic fields. Also, gravitational waves in the early Universe and from the merger of neutron stars, black holes etc. may enhance $CP-$violation and generate an imbalance in chiral charge distributions, magnetic fields etc.

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S. Dave, S. Digal and V. Mamale
Thu, 19 Jan 23
78/100

Comments: 19 pages, 16 figures

Implication of island for inflation and primordial perturbations [CL]

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http://arxiv.org/abs/2301.07403


It is usually thought that the efolds number of inflation must be bounded by its de Sitter entropy, otherwise we will have an information paradox. However, in light of the island rule for computing the entanglement entropy, we show that such a bound might be nonexistent, while the information flux of primordial perturbation modes the observer after inflation is able to detect follows a Page curve. In corresponding eternally inflating spacetime, it seems that our inflating patch must be accompanied with a neighbourly collapsed patch (eventually developing into a black hole) so that its Hawking radiation might be just our primordial perturbations. Accordingly, the perturbation spectrum we observed will present a “Page-like” suppression at large scale.

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Y. Piao
Thu, 19 Jan 23
79/100

Comments: 22 pages, 7 figures

Remnant black hole properties from numerical-relativity-informed perturbation theory and implications for waveform modelling [CL]

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http://arxiv.org/abs/2301.07215


During binary-black-hole (BBH) mergers, energy and momenta are carried away from the binary system as gravitational radiation. Access to the radiated energy and momenta allows us to accurately predict the properties of the remnant black hole. We develop a python package gw_remnant to efficiently extract the remnant mass, remnant spin, peak luminosity and the final kick imparted on the remnant black hole directly from the gravitational radiation. We then compute the remnant properties of the final black hole in case of non-spinning BBH mergers with mass ratios ranging from q=2.5 to q=1000 using waveforms generated from BHPTNRSur1dq1e4, a recently developed numerical relativity informed surrogate model based on black-hole perturbation theory framework. We validate our results against the remnant properties estimated from numerical relativity (NR) surrogate models in the comparable mass ratio regime and against recently available high-mass ratio RIT NR simulations at q=[15,32,64]. We find that our remnant property estimates match very closely to the estimates obtained from NR surrogate model and the NR data respectively in both the regimes. We then present BHPTNR_Remnant, a surrogate model for the properties of the remnant black hole in BBH mergers with q=2.5 to q=1000, using Gaussian process regression fitting methods. Finally, we comment on the possible implication of remnant information in gravitational waveform modelling. We make both the gw_remnant and BHPTNR_Remnant packages publicly available.

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T. Islam, S. Field and G. Khanna
Thu, 19 Jan 23
82/100

Comments: 14 pages, 7 figures

A stochastic search for intermittent gravitational-wave backgrounds [CL]

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http://arxiv.org/abs/2301.07675


A likely source of a gravitational-wave background (GWB) in the frequency band of the Advanced LIGO, Virgo and KAGRA detectors is the superposition of signals from the population of unresolvable stellar-mass binary-black-hole (BBH) mergers throughout the Universe. Since the duration of a BBH merger in band ($\sim!1~{\rm s}$) is much shorter than the expected separation between neighboring mergers ($\sim!10^3~{\rm s}$), the observed signal will be “popcorn-like” or intermittent with duty cycles of order $10^{-3}$. However, the standard cross-correlation search for stochastic GWBs currently performed by the LIGO-Virgo-KAGRA collaboration is based on a continuous-Gaussian signal model, which does not take into account the intermittent nature of the background. The latter is better described by a Gaussian mixture-model, which includes a duty cycle parameter that quantifies the degree of intermittence. Building on an earlier paper by Drasco and Flanagan, we propose a stochastic-signal-based search for intermittent GWBs. For such signals, this search performs better than the standard continuous cross-correlation search. We present results of our stochastic-signal-based approach for intermittent GWBs applied to simulated data for some simple models, and compare its performance to the other search methods, both in terms of detection and signal characterization. Additional testing on more realistic simulated data sets, e.g., consisting of astrophysically-motivated BBH merger signals injected into colored detector noise containing noise transients, will be needed before this method can be applied with confidence on real gravitational-wave data.

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J. Lawrence, K. Turbang, A. Matas, et. al.
Thu, 19 Jan 23
90/100

Comments: 23 pages, 8 figures, 1 table

Backreaction in cosmic screening approach [CL]

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http://arxiv.org/abs/2301.06886


We investigate the backreaction of nonlinear perturbations on the global evolution of the Universe within the cosmic screening approach. To this end, we have considered the second-order scalar perturbations. An analytical study of these perturbations followed by a numerical evaluation shows that, first, the corresponding average values have a negligible backreaction effect on the Friedmann equations and, second, the second-order correction to the gravitational potential is much less than the first-order quantity. Consequently, the expansion of perturbations into orders of smallness in the cosmic screening approach is correct.

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M. Eingorn, B. O’Briant, A. Diouf, et. al.
Thu, 19 Jan 23
91/100

Comments: 11 pages, 2 figures

Revisiting the stability of strange-dwarf stars and strange planets [CL]

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http://arxiv.org/abs/2301.07654


The dynamical stability of strange-dwarf hybrid stars and strange planets, constituted by strange-quark-matter cores and dilute-nuclear-matter crusts, is revisited by analyzing the fundamental mode eigenfrequencies of the radial oscillation equations with non-trivial boundary conditions for slow and fast conversions characterizing distinct microphysical scales originating at the density-discontinuous interface. Our calculations indicate that in the case of rapid conversions the so-called {\it reaction mode} plays the fundamental role in these non-compact objects and allow their existence in nature. Interestingly, slow conversions display the same stability window as the seminal work of Glendenning-Kettner-Weber. The robustness of our findings is demonstrated for different transition densities and also using an equation of state from perturbative QCD for the ultra-dense core.

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V. Goncalves, J. Jimenez and L. Lazzari
Thu, 19 Jan 23
96/100

Comments: 6 pages, 3 figures

On the Interaction between Ultralight Bosons and Quantum-Corrected Black Holes [CL]

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http://arxiv.org/abs/2301.06840


Both ultralight dark matter and exploring the quantum nature of black holes are all topics of great interest in gravitational wave astronomy at present. The superradiant instability allows an exotic compact object (ECO) to be surrounded by an ultralight boson cloud, which leads to the emission of gravitational waves and further triggers rich dynamical effects. In this paper, we study the gravitational effects of superradiant instabilities by calculating the energy fluxes of gravitational waves emitted from ultralight scalar dark matter fields by solving the Teukolsky equation in the background of a massive ECO phenomenologically described by a Kerr geometry with a reflective boundary condition at its physical boundary. We find that both the amplitude and phase of the reflectivity will either suppress or enhance the energy flux of GWs by several orders of magnitude if $M\mu \gtrsim 0.5$ where $M$ and $\mu$ are the mass of ECO and boson, respectively. However, the modifications to energy flux are negligible if $M \mu \lesssim 0.5$. Our results suggest that reflectivity will play a significant role in the near-horizon physics of ECO.

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R. Guo, C. Yuan and Q. Huang
Wed, 18 Jan 23
3/133

Comments: 20 pages, 6 figures

Closed-Form Formulae for Inflation Correlators [CL]

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http://arxiv.org/abs/2301.07047


We derive exact and closed-form expressions for a large class of two-point and three-point inflation correlators with the tree-level exchange of a single massive particle. The intermediate massive particle is allowed to have arbitrary mass, spin, chemical potential, and arbitrary nonderivative or derivative couplings to external inflaton modes. We also allow the coupling coefficients to have arbitrary complex power dependences on the conformal time. Our results feature closed-form expressions involving only familiar special functions and without any infinite sums. This is achieved by an improved bootstrap method with a suitable change of variables. Our results cover a wide range of cosmological collider models and can be directly used for future phenomenological studies. Our results can also be used as basic building blocks for constructing more complicated inflation correlators.

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Z. Qin and Z. Xianyu
Wed, 18 Jan 23
9/133

Comments: 41 pages

Solving both $H_0$ and $σ_8$ tensions in $f(T)$ gravity [CL]

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http://arxiv.org/abs/2301.06881


We report how to alleviate both the $H_0$ and $\sigma_8$ tensions simultaneously within $f(T)$ gravity. In particular, we consider the parametrization $f(T)=-T-2\Lambda/M_P^2+\alpha T^\beta$, where two out of the three parameters are independent. This model can efficiently fit observations solving the two tensions. To our knowledge, this is the first time where a modified gravity theory can alleviate both $H_0$ and $\sigma_8$ tensions simultaneously, hence, offering an additional argument in favor of gravitational modification.

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E. Saridakis
Wed, 18 Jan 23
16/133

Comments: 10 pages, 3 figures, Invited talk at the 16th Marcel Grossmann meeting, based on arXiv:1909.06388 . Published at the proceedings of MG16

First demonstration of neural sensing and control in a kilometer-scale gravitational wave observatory [CL]

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http://arxiv.org/abs/2301.06221


Suspended optics in gravitational wave (GW) observatories are susceptible to alignment perturbations and, in particular, to slow drifts over time due to variations in temperature and seismic levels. Such misalignments affect the coupling of the incident laser beam into the optical cavities, degrade both circulating power and optomechanical photon squeezing, and thus decrease the astrophysical sensitivity to merging binaries. Traditional alignment techniques involve differential wavefront sensing using multiple quadrant photodiodes, but are often restricted in bandwidth and are limited by the sensing noise. We present the first-ever successful implementation of neural network-based sensing and control at a gravitational wave observatory and demonstrate low-frequency control of the signal recycling mirror at the GEO 600 detector. Alignment information for three critical optics is simultaneously extracted from the interferometric dark port camera images via a CNN-LSTM network architecture and is then used for MIMO control using soft actor-critic-based deep reinforcement learning. Overall sensitivity improvement achieved using our scheme demonstrates deep learning’s capabilities as a viable tool for real-time sensing and control for current and next-generation GW interferometers.

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N. Mukund, J. Lough, A. Bisht, et. al.
Wed, 18 Jan 23
22/133

Comments: 14 pages, 11 figures

Slowly rotating Tolman VII solution [CL]

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http://arxiv.org/abs/2301.06960


We present a model of a slowly rotating Tolman VII (T-VII) fluid sphere, at second order in the angular velocity. The structure of this configuration is obtained by integrating the Hartle-Thorne equations for slowly rotating relativistic masses. We model a sequence in adiabatic and quasi-stationary contraction, by varying the tenuity parameter $R/R_{\mathrm{S}}$, where $R$ is the radius of the configuration and $R_{\mathrm{S}}$ is its Schwarzschild radius. We determined the moment of inertia $I$, mass quadrupole moment $Q$, and the ellipticity $\varepsilon$, for various configurations. Similar to previous results for Maclaurin and polytropic spheroids, in slow rotation, we found a change in the behaviour of the ellipticity when the tenuity reaches a certain critical value. We compared our results of $I$ and $Q$ for the T-VII model with those predicted by the universal fittings proposed for realistic neutron stars. For the relevant range of compactness, we found that relative errors are within $10\%$, thus suggesting the T-VII solution as a very good approximation for the description of the interior of neutron stars.

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C. Posada and Z. Stuchlík
Wed, 18 Jan 23
30/133

Comments: 20 pages, 10 figures

Many-body neutrino flavor entanglement in a simple dynamic model [CL]

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http://arxiv.org/abs/2301.07049


Dense neutrino gases form in extreme astrophysical sites, and the flavor content of the neutrinos likely has an important impact on the subsequent dynamical evolution of their environment. Through coherent forward scattering among neutrinos, the flavor content of the gas evolves under a time-dependent potential which can be modeled in a quantum many-body formalism as an all-to-all coupled spin-spin interaction. This two-body potential generically introduces entanglement and greatly complicates the study of these systems. In this work we study the evolution of the quantum many-body problem as well as the typically employed mean-field approximation to it for a small number of neutrinos ($N = 16$). We consider randomly chosen one- and two-body couplings in the Hamiltonian, and the resulting evolution of several initial product states. We subsequently compare many-body and mean-field predictions for one-body observables, and we consider one- and two-body entanglement to assess under what conditions the many-body and mean-field predictions are likely to disagree. Except for a special category of prototypical initial conditions, we find that the typically employed mean-field approximation is insufficient to capture the evolution of one-body operators in the systems we consider. We also observe a loss of coherence in one- and two-body trace-reduced subsystems which suggests that the evolution may be well approximated as a classical mixture of separable states.

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J. Martin, A. Roggero, H. Duan, et. al.
Wed, 18 Jan 23
36/133

Comments: 6 pages, 5 figures

Ekpyrotic Inflation: Transient Acceleration after Non-minimal M-flation Preheating [CL]

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http://arxiv.org/abs/2301.06598


Light massive preheat fields acquire a non-vanishing dispersion during parametric resonance from their quantum particle production. This in turn will modify the inflaton potential, which in some cases can induce a transient period of acceleration. We illustrate this phenomenon in the setup of non-supersymmetric non-minimal M-flation (non-$\mathbb{M}$-flation) which has some motivations from the brane compactifications in string theory. Implementing a lattice simulation by the LATTICEEASY code, we compute the potential correction term in our scenario and show that the modified term indeed causes the universe to make a transition from the decelerated expansion to a temporary phase of acceleration. The correction term reduces to some extent the number density of the particles generated during preheating, but the efficiency of preheating remains still enough to have successful particle production after inflation. We also compute the spectrum of the gravitational waves (GWs) generated during preheating in our setup by using the LATTICEEASY code. Although the peak frequency remains almost the same, the inclusion of the correction term reduces the amplitude of the gravitational spectrum by almost one order of magnitude.

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A. Ashoorioon and K. Rezazadeh
Wed, 18 Jan 23
43/133

Comments: 21 pages, 13 figures

Testing heavy neutral leptons produced in the supernovae explosions with future neutrino detectors [CL]

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http://arxiv.org/abs/2301.07052


Hypothetical particles called heavy neutral leptons (HNLs) can be produced in large quantities in the cores of supernovae during the first seconds of the explosion. These particles then decay, producing secondary energetic neutrinos that can be detected by neutrino detectors. In this paper, I identify a region of the HNL parameter space that could be tested using this method, assuming a supernova explosion at distances from 0.2 to 10 kpc. The range of HNLs masses $m_N \sim 160-700$ MeV and lifetimes of $\tau_N \gtrsim 0.02$ seconds can be probed using the Hyper-Kamiokande neutrino detector. This region of the parameter space is complementary to existing bounds from primordial nucleosynthesis and to the expected sensitivity of the future SHiP experiment, thus covering a gap in our current knowledge of HNLs up to masses of $m_N \simeq 400$ MeV.

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V. Syvolap
Wed, 18 Jan 23
46/133

Comments: N/A

Search for gravitational-wave bursts in LIGO data at the Schenberg antenna sensitivity range [CL]

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http://arxiv.org/abs/2301.06751


The Brazilian gravitational-wave detector Mario Schenberg was conceived in the early 2000s and operated until 2016 when it was dismantled. A straight path to evaluate the viability of the reassembly of the Schenberg antenna is to verify the possibility of detecting gravitational wave (GW) signals within its design sensitivity features. The eventual identification of significant signals would operate as motivation for the Schenberg rebuild. As the antenna was dismantled, we can get some indication from the third observing run (O3) data of the LIGO detectors. It is based on the similarity between Schenberg sensitivity and the sensitivity of the interferometers in the O3 [3150-3260] Hz band. We search for signals with milliseconds to a few seconds without making assumptions about their morphology, polarization, and arrival sky direction. The data were analyzed with the coherent WaveBurst pipeline (cWB) with frequencies from 512 Hz to 4096 Hz and the search targets only signals with bandwidth overlapping the Schenberg frequency band. No statistically significant evidence of GW bursts during O3 was found. The null result was used to feature the search efficiency in identifying different simulated signal morphologies and establish upper limits on the GW burst event rate as a function of its strain amplitude. The present search, and consequently Schenberg, is sensitive to sources emitting isotropically 5 x 10e(-6) M_sun c^2 in GWs from a distance of 10 kpc with 50% detection efficiency and with a false alarm rate of 1/100 years. The feasibility of detecting f-modes of neutron stars excited by glitches was also investigated. The Schenberg antenna would need at least 5.3 years of observation run to get a single detection of the f-mode signal, given E_(glitch) approx 10e(-10) M_sun c^2.

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J. Martins, I. Heng, I. Melo, et. al.
Wed, 18 Jan 23
56/133

Comments: N/A

A unified effective approach to cosmological perturbations [CL]

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http://arxiv.org/abs/2301.05679


A unified model independent effective description of cosmological perturbations is derived in terms of two effective quantities, playing the role of effective propagation speeds of curvature perturbations and gravitational waves, encoding the effects of the interaction of perturbations at any order, and inducing a modification of the friction term of the perturbations propagation equation. The approach can be applied to dark energy, modified gravity, dark matter, for fields of arbitrary number and spin, and is particularly suitable for model independent analysis of observational data. The structure of the effective actions and equations is the same for scalar and tensor perturbations.
The effective actions can be written as the Klein-Gordon action in terms of an appropriately defined effective metric, dependent on the effective speed. In this geometrical interpretation, the effective metric emerges as the result of the interaction and self-interaction of perturbations, hinting to possible connections with emergent gravity.
As an example of an application we find that the effective speeds of curvature perturbations and gravitational waves can be frequency and polarization dependent even for a minimally coupled scalar field in general relativity, when higher order terms effects are computed, going beyond the quadratic action, or in axion inflation. We discuss the relation between the effective speed and quantum correlators.

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A. Romano
Wed, 18 Jan 23
73/133

Comments: N/A

Sky localization of space-based detectors with time-delay interferometry [CL]

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http://arxiv.org/abs/2301.05923


The accurate sky localization of gravitational wave (GW) sources is an important scientific goal for space-based GW detectors. Due to the effects of gravity on three spacecrafts, it is hard to maintain the equality of the arm length, so the time-delay interferometry (TDI) method is needed to cancel out the laser frequency noise for space-based GW detectors. By considering the first-generation TDI combination, we employ the Fisher information matrix to study the accuracy of sky localizations for future space-based GW detectors and their combined network. The main difference between future space-based GW detectors includes the time-changing orientation of the detector plane, the arm length, the orbital period of spacecrafts and the noise curve. We study the effects of these factors on the accuracy of source localization at different frequencies. We find that the amplitude modulation caused by the rotation of the detector plane can help LISA and Taiji not only to improve the accuracy of source localization but also to enlarge the sky coverage at frequencies below 1 mHz. As the frequency of monochromatic GWs increases, the Doppler modulation becomes dominate and the equatorial pattern appears in the sky map. The effect of arm length on the angular resolution mainly comes from the noise curve and it is almost the same for both heliocentric and geocentric constellations. The orbital period of the spacecrafts has little effect on the angular resolutions. The improvement on the angular resolutions by the network of combined detectors is small compared with a single detector and the angular resolutions are almost the same with and without the TDI combination.

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T. Jiang, Y. Gong and X. Lu
Wed, 18 Jan 23
76/133

Comments: 24 pages, 8 figures

Roger of Hereford: the twelfth-century astronomer who put Hereford on the map, literally [CL]

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http://arxiv.org/abs/2301.06610


By the twelfth century, northern European scholars gradually embraced Arabic innovations in science and technology. England naturally developed into a significant centre of the new learning in western Europe. Hereford, and specifically its cathedral school, played a particularly important role in the transition of English scholarship to the new learning. Hereford cathedral developed into a focal point for high-level scholarship, attracting numerous scholars from across the continent. Roger of Hereford stands out among his peers as an enlightened scholar who made more practical use than most of the full astronomical and astrological knowledge base available in England at the time. A significant body of recent scholarship focuses on twelfth-century ecclesiastical developments, including those relating to Roger of Hereford’s Computus. However, much less scholarly emphasis is placed on Roger’s astronomical calculations, particularly those which allowed him to establish an important reference meridian at Hereford. Those aspects are the focus of this paper.

Read this paper on arXiv…

R. Grijs
Wed, 18 Jan 23
79/133

Comments: 17 pages, 5 figures; The Local Historian, in press (April 2023 issue; note that the version of record will have B/W figures)

Stability of electrically charged stars, regular black holes, quasiblack holes, and quasinonblack holes [CL]

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http://arxiv.org/abs/2301.06563


The stability of a class of electrically charged fluid spheres under radial perturbations is studied. Among these spheres there are regular stars, overcharged tension stars, regular black holes, quasiblack holes, and quasinonblack holes, all of which have a Reissner-Nordstr\”om exterior. We formulate the dynamical perturbed equations by following the Chandrasekhar approach and investigate the stability against radial perturbations through numerical methods. It is found that (i) under certain conditions that depend on the adiabatic index of the radial perturbation, there are stable charged stars and stable tension stars; (ii) also depending on the adiabatic index there are stable regular black holes; (iii) quasiblack hole configurations formed by, e.g., charging regular pressure stars or by discharging regular tension stars, can be stable against radial perturbations for reasonable values of the adiabatic index; (iv) quasinonblack holes are unstable against radial perturbations.

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A. Masa, J. Lemos and V. Zanchin
Wed, 18 Jan 23
105/133

Comments: 38 pages, 15 figures, 18 tables

TDiff invariant field theories for cosmology [CL]

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http://arxiv.org/abs/2301.05713


We study scalar field theories invariant under transverse diffeomorphisms in cosmological contexts. We show that in the geometric optics approximation, the corresponding particles move along geodesics and contribute with the same active mass (energy) to the gravitational field as in Diff invariant theories. However, for low-frequency modes, the contributions to the energy-momentum tensor differ from that of Diff invariant theories. This opens up a wide range of possibilities for cosmological model building. As an example, we show that the simplest TDiff invariant scalar field theory with only kinetic term could drive inflation and generate a red-tilted spectrum of density fluctuations. We also present a detailed analysis of cosmological perturbations and show that the breaking of full Diff invariance generically induces new non-adiabatic pressure perturbations. A simple scalar field dark matter model based on a purely kinetic term that exhibits the same clustering properties as standard cold dark matter is also presented.

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A. Maroto
Wed, 18 Jan 23
109/133

Comments: 15 pages

Gravitational wave spectral synthesis [CL]

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http://arxiv.org/abs/2301.06888


We study the LISA sources that arise from isolated binary evolution, and how these depend on age and metallicity, using model stellar populations from BPASS. We calculate the combined GW spectrum of all the binaries within these populations, including all types of compact binaries as well as those with living stars, and use these results to investigate the detectability of star clusters with LISA. We find at late times the dominant sources are WD-WD binaries, but at times before approx. $10^9$ years we find a significant population of NS-WD and BH-WD binaries, which is related to the treatment of mass transfer and common envelope events in BPASS, wherein mass transfer is relatively likely to be stable. Metallicity also has an effect on the GW spectrum and on the relative dominance of different types of binaries. Our results suggest that nearby star clusters might produce GWs detectable by LISA or future missions throughout most of their evolution.

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W. Zeist, J. Eldridge and P. Tang
Wed, 18 Jan 23
115/133

Comments: 16 pages, 9 figures. Submitted to MNRAS

Probing the Blue Axion with Cosmic Optical Background Anisotropies [CL]

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http://arxiv.org/abs/2301.06560


A radiative decaying Big Bang relic with a mass $m_a\simeq 5-25 \,\rm eV$, which we dub “blue axion”, can be probed with direct and indirect observations of the cosmic optical background (COB). The strongest bounds on blue-axion cold dark matter come from the Hubble Space Telescope (HST) measurements of COB anisotropies at $606$ nm. We suggest that new HST measurements at higher frequencies ($336$ nm and $438$ nm) can improve current constraints on the lifetime up to an order of magnitude, and we show that also thermally produced and hot relic blue axions can be competitively probed by COB anisotropies. We exclude the simple interpretation of the excess in the diffuse COB detected by Long Range Reconnaissance Imager (LORRI) as photons produced by a decaying hot relic. Finally, we comment on the reach of upcoming line intensity mapping experiments, that could detect blue axions with a lifetime as large as $10^{29}\,\rm s$ or $10^{27}\,\rm s$ for the cold dark matter and the hot relic case, respectively.

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P. Carenza, G. Lucente and E. Vitagliano
Wed, 18 Jan 23
121/133

Comments: 21 pages, 12 figures

Waveform uncertainty quantification and interpretation for gravitational-wave astronomy [CL]

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http://arxiv.org/abs/2301.06630


We demonstrate how to quantify the frequency-domain amplitude and phase accuracy of waveform models, $\delta A$ and $\delta \phi$, in a form that could be marginalized over in gravitational-wave inference using techniques currently applied for quantifying calibration uncertainty. For concreteness, waveform uncertainties affecting neutron-star inspiral measurements are considered, and post-hoc error estimates from a variety of waveform models are made by comparing time-domain and frequency-domain analytic models with multiple-resolution numerical simulations. These waveform uncertainty estimates can be compared to GW170817 calibration envelopes or to Advanced LIGO and Virgo calibration goals. Signal-specific calibration and waveform uncertainties are compared to statistical fluctuations in gravitational-wave observatories, giving frequency-dependent modeling requirements for detectors such as Advanced LIGO Plus, Cosmic Explorer, or Einstein Telescope. Finally, the distribution of waveform error for GW170817 over the parameters of the low-spin posterior is computed from tidal models and compared to the constraints on $\delta \phi$ or $\delta A$ from GWTC-1 by Edelman et. al. In general, $\delta \phi$ and $\delta A$ can also be interpreted in terms of unmodeled astrophysical energy transfer within or from the source system.

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J. Read
Wed, 18 Jan 23
124/133

Comments: 26 pages, 6 figures, submitted to CQG

Astrophysical consequences of dark matter for photon orbits and shadows of supermassive black holes [CL]

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http://arxiv.org/abs/2301.06373


We consider Kerr black holes (BHs) surrounded by perfect dark fluid matter (PFDM), with an additional parameter ($k$) because of PFDM, apart from mass ($M$) and rotation parameter ($a$) — the rotating PFDM BHs. We analyze the photon orbits around PFDM BHs and naked singularities (NSs) and emphasise the effect of PFDM on photon boomerangs. Interestingly, the azimuthal oscillations first increase and then decrease for retrograde orbits, whereas they first decrease and then increase for prograde orbits, with increasing $k$. Unlike in the Kerr NSs, photon boomerangs can form around rotating PFDM NSs. We use the Event Horizon Telescope (EHT) observational results for Schwarzschild shadow deviations of M87* and Sgr A*, $\delta_{M87^}=-0.01\pm0.17$ and $\delta_{Sgr A^} = -0.08^{+0.09}{-0.09}~\text{(VLTI)},-0.04^{+0.09}{-0.10}~\text{(Keck)}$, to report the upper bounds on the PFDM parameter: $0\leq k\leq 0.0792M$ and $k^{max}\in[0.0507M, 0.0611M]$ respectively. Together with the EHT bounds on the shadows of Sgr A$^$ and M87$^$, our analysis concludes that a substantial part of the rotating PFDM BH parameter space agrees with the EHT observations. Thus, one must consider the possibility of the rotating PFDM BHs being strong candidates for the astrophysical BHs.

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A. Anjum, M. Afrin and S. Ghosh
Wed, 18 Jan 23
126/133

Comments: 17 pages, 16 figures, 6 tables

Black hole spectroscopy by mode cleaning [CL]

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http://arxiv.org/abs/2301.06705


We formulate a Bayesian framework to analyze ringdown gravitational waves from colliding binary black holes and test the no-hair theorem. The idea hinges on mode cleaning — revealing subdominant oscillation modes by removing dominant ones using newly proposed ${\it rational~filters}$. By incorporating the filter into Bayesian inference, we construct a likelihood function that depends only on the mass and spin of the remnant black hole (no dependence on mode amplitudes and phases) and implement an efficient pipeline to constrain the remnant mass and spin without Markov chain Monte Carlo (MCMC). We test ringdown models by cleaning combinations of different modes and evaluating the consistency between the residual data and pure noise. The model evidence and Bayes factor are used to demonstrate the presence of a particular mode and to infer the mode starting time. In addition, we design a hybrid approach to estimate the remnant black hole properties exclusively from a single mode using MCMC after mode cleaning. We apply the framework to GW150914 and demonstrate more definitive evidence of the first overtone by cleaning the fundamental mode. This new framework provides a powerful tool for black hole spectroscopy in future gravitational-wave events.

Read this paper on arXiv…

S. Ma, L. Sun and Y. Chen
Wed, 18 Jan 23
132/133

Comments: N/A

Nonprofit Adopt a Star: Lessons from 15 years of Crowdfunding [CL]

Posted on by

http://arxiv.org/abs/2301.05598


In the past 15 years, the number of known planets outside of our solar system has grown from about 200 to more than 5000. During that time, we have conducted one of the longest crowdfunding campaigns in history, a nonprofit adopt a star program that supports astronomy research. The program includes the targets of NASA space telescopes that are searching for planets around other stars, and it uses the proceeds to help determine the properties of those stars and their planetary systems. I summarize how this innovative program has evolved over the years and engaged the public worldwide to support an international team of astronomers.

Read this paper on arXiv…

T. Metcalfe
Mon, 16 Jan 23
4/50

Comments: 4 pages, 2 figures. Project website is at this https URL

Impact of high-scale Seesaw and Leptogenesis on inflationary tensor perturbations as detectable gravitational waves [CL]

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http://arxiv.org/abs/2301.05672


We discuss the damping of inflationary gravitational waves (GW) that re-enter the horizon before or during an epoch, where the energy budget of the universe is dominated by an unstable right handed neutrino (RHN), whose out of equilibrium decay releases entropy. Starting from the minimal Standard Model extension, motivated by the observed neutrino mass scale, with nothing more than 3 RHN for the Seesaw mechanism, we discuss the conditions for high scale leptogenesis assuming a thermal initial population of RHN. We further address the associated production of potentially light non-thermal dark matter and a potential component of dark radiation from the same RHN decay. One of our main findings is that the frequency, above which the damping of the tensor modes is potentially observable, is completely determined by successful leptogenesis and a Davidson-Ibarra type bound to be at around $0.1\;\text{Hz}$. To quantify the detection prospects of this GW background for various proposed interferometers such as AEDGE, BBO, DECIGO, Einstein Telescope or LISA we compute the signal-to-noise ratio (SNR). This allows us to investigate the viable parameter space of our model, spanned by the mass of the decaying RHN $M_1 \gtrsim 2.4\times 10^8\;\text{GeV} \cdot \sqrt{2\times 10^{-7}\;\text{eV}/\tilde{m}_1}$ (for leptogenesis) and the effective neutrino mass parameterizing its decay width $\tilde{m}_1< 2.9\times 10^{-7}\;\text{eV}$ (for RHN matter domination). Thus gravitational wave astronomy is a novel way to probe both the Seesaw and the leptogenesis scale, which are completely inaccessible to laboratory experiments in high scale scenarios.

Read this paper on arXiv…

M. Berbig and A. Ghoshal
Mon, 16 Jan 23
30/50

Comments: v1: 24 pages, 16 figures, comments are always welcome!

Mass production of ultra-pure NaI powder for COSINE-200 [CL]

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http://arxiv.org/abs/2301.05400


COSINE-200 is the next phase experiment of the ongoing COSINE-100 that aims to unambiguously verify the annual modulation signals observed by the DAMA experiment and to reach the world competitive sensitivity on the low-mass dark matter search. To achieve the physics goal of the COSINE-200, the successful production of the low-background NaI(Tl) detectors is crucial and it must begin from the mass production of the ultra-low background NaI powder. A clean facility for mass-producing the pure-NaI powder has been constructed at the Center for Underground Physics (CUP) in Korea. Two years of operation determined efficient parameters of the mass purification and provided a total of 480 kg of the ultra-pure NaI powder in hand. The potassium concentration in the produced powders varied from 5.4 to 11 ppb, and the maximum production capacity of 35 kg per two weeks was achieved. Here, we report our operational practice with the mass purification of the NaI powder, which includes raw powder purification, recycling of the mother solution, and recovery of NaI from the residual melt that remained after crystal growth.

Read this paper on arXiv…

K. Shin, J. Choe, O. Gileva, et. al.
Mon, 16 Jan 23
45/50

Comments: N/A

Mass production of ultra-pure NaI powder for COSINE-200 [CL]

Posted on by

http://arxiv.org/abs/2301.05400


COSINE-200 is the next phase experiment of the ongoing COSINE-100 that aims to unambiguously verify the annual modulation signals observed by the DAMA experiment and to reach the world competitive sensitivity on the low-mass dark matter search. To achieve the physics goal of the COSINE-200, the successful production of the low-background NaI(Tl) detectors is crucial and it must begin from the mass production of the ultra-low background NaI powder. A clean facility for mass-producing the pure-NaI powder has been constructed at the Center for Underground Physics (CUP) in Korea. Two years of operation determined efficient parameters of the mass purification and provided a total of 480 kg of the ultra-pure NaI powder in hand. The potassium concentration in the produced powders varied from 5.4 to 11 ppb, and the maximum production capacity of 35 kg per two weeks was achieved. Here, we report our operational practice with the mass purification of the NaI powder, which includes raw powder purification, recycling of the mother solution, and recovery of NaI from the residual melt that remained after crystal growth.

Read this paper on arXiv…

K. Shin, J. Choe, O. Gileva, et. al.
Mon, 16 Jan 23
7/50

Comments: N/A

Nonprofit Adopt a Star: Lessons from 15 years of Crowdfunding [CL]

Posted on by

http://arxiv.org/abs/2301.05598


In the past 15 years, the number of known planets outside of our solar system has grown from about 200 to more than 5000. During that time, we have conducted one of the longest crowdfunding campaigns in history, a nonprofit adopt a star program that supports astronomy research. The program includes the targets of NASA space telescopes that are searching for planets around other stars, and it uses the proceeds to help determine the properties of those stars and their planetary systems. I summarize how this innovative program has evolved over the years and engaged the public worldwide to support an international team of astronomers.

Read this paper on arXiv…

T. Metcalfe
Mon, 16 Jan 23
14/50

Comments: 4 pages, 2 figures. Project website is at this https URL

Impact of high-scale Seesaw and Leptogenesis on inflationary tensor perturbations as detectable gravitational waves [CL]

Posted on by

http://arxiv.org/abs/2301.05672


We discuss the damping of inflationary gravitational waves (GW) that re-enter the horizon before or during an epoch, where the energy budget of the universe is dominated by an unstable right handed neutrino (RHN), whose out of equilibrium decay releases entropy. Starting from the minimal Standard Model extension, motivated by the observed neutrino mass scale, with nothing more than 3 RHN for the Seesaw mechanism, we discuss the conditions for high scale leptogenesis assuming a thermal initial population of RHN. We further address the associated production of potentially light non-thermal dark matter and a potential component of dark radiation from the same RHN decay. One of our main findings is that the frequency, above which the damping of the tensor modes is potentially observable, is completely determined by successful leptogenesis and a Davidson-Ibarra type bound to be at around $0.1\;\text{Hz}$. To quantify the detection prospects of this GW background for various proposed interferometers such as AEDGE, BBO, DECIGO, Einstein Telescope or LISA we compute the signal-to-noise ratio (SNR). This allows us to investigate the viable parameter space of our model, spanned by the mass of the decaying RHN $M_1 \gtrsim 2.4\times 10^8\;\text{GeV} \cdot \sqrt{2\times 10^{-7}\;\text{eV}/\tilde{m}_1}$ (for leptogenesis) and the effective neutrino mass parameterizing its decay width $\tilde{m}_1< 2.9\times 10^{-7}\;\text{eV}$ (for RHN matter domination). Thus gravitational wave astronomy is a novel way to probe both the Seesaw and the leptogenesis scale, which are completely inaccessible to laboratory experiments in high scale scenarios.

Read this paper on arXiv…

M. Berbig and A. Ghoshal
Mon, 16 Jan 23
40/50

Comments: v1: 24 pages, 16 figures, comments are always welcome!

Tidal deformations of a binary system induced by an external Kerr black hole [CL]

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http://arxiv.org/abs/2301.04879


The dynamics of a binary system moving in the background of a black hole is affected by tidal forces. In this work, for the Kerr black hole, we derive the electric and magnetic tidal moments at quadrupole order, where the latter are computed for the first time in full generality. We make use of these moments in the scenario of a hierarchical triple system made of a Kerr black hole and an extreme-mass ratio binary system consisting of a Schwarzschild black hole and a test particle. We study how the secular dynamics of the test particle in the binary system is distorted by the presence of tidal forces from a much larger Kerr black hole. Our treatment includes strong gravitational effects beyond the post-Newtonian approximation both for the binary system and for the tidal forces since the binary system is allowed to be close to the event horizon of the Kerr black hole. We compute the shifts in the physical quantities for the secular dynamics of the test particle and show that they are gauge-invariant. In particular, we apply our formalism to the innermost stable circular orbit for the test particle and to the case of the photon sphere. Our results are relevant for the astrophysical situation in which the binary system is in the vicinity of a supermassive black hole.

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F. Camilloni, G. Grignani, T. Harmark, et. al.
Fri, 13 Jan 23
2/72

Comments: 27 pages, 3 figures

Gauge invariant theory of gravity in spacetime with gradient nonmetricity: A possible resolution of several cosmological puzzles [CL]

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http://arxiv.org/abs/2301.05007


In this paper we apply the symmetry principle in order to search for an alternative unified explanation of several cosmological puzzles such as the present stage of accelerated expansion of the Universe and the Hubble tension issue, among others. We argue that Weyl gauge symmetry, being a manifest symmetry of gauge invariant theories of gravity operating on Weyl integrable geometry spacetimes, may be an actual (unbroken) symmetry of our present Universe. This symmetry may be at the core of a phenomenologically feasible explanation of modern fundamental issues arising within the framework of general relativity and of its known modifications.

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I. Quiros
Fri, 13 Jan 23
29/72

Comments: 27 pages, 2 figures. This paper complements arXiv:2208.10048

Extreme mass ratio inspirals in galaxies with dark matter halos [CL]

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http://arxiv.org/abs/2301.05088


Using the analytic, static and spherically symmetric metric for a Schwarzschild black hole immersed in dark matter (DM) halos with Hernquist type density distribution, we derive analytic formulae for the orbital period and orbital precession, the evolutions of the semi-latus rectum and the eccentricity for eccentric EMRIs with the environment of DM halos. We show how orbital precessions are decreased and even reverse the direction if the density of DM halo is large enough. The presence of local DM halos slows down the decrease of the semi-latus rectum and the eccentricity. Comparing the number of orbital cycles with and without DM halos over one-year evolution before the merger, we find that DM halos with the compactness as small as $10^{-4}$ can be detected. By calculating the mismatch between GW waveforms with and without DM halos, we show that we can use GWs from EMRIs in the environments of galaxies to test the existence of DM halos and detect the compactness as small as $10^{-5}$.

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N. Dai, Y. Gong, Y. Zhao, et. al.
Fri, 13 Jan 23
30/72

Comments: 21 pages, 6 figures

Probing lens-induced gravitational-wave birefringence as a test of general relativity [CL]

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http://arxiv.org/abs/2301.04826


Theories beyond general relativity (GR) modify the propagation of gravitational waves (GWs). In some, inhomogeneities (aka. gravitational lenses) allow interactions between the metric and additional fields to cause lens-induced birefringence (LIB): a different speed of the two linear GW polarisations ($+$ and $\times$). Inhomogeneities then act as non-isotropic crystals, splitting the GW signal into two components whose relative time delay depends on the theory and lens parameters. Here we study the observational prospects for GW scrambling, i.e when the time delay between both GW polarisations is smaller than the signal’s duration and the waveform recorded by a detector is distorted. We analyze the latest LIGO-Virgo-KAGRA catalog, GWTC-3, and find no conclusive evidence for LIB. The highest log Bayes factor that we find in favour of LIB is $3.21$ for GW$190521$, a particularly loud but short event. However, when accounting for false alarms due to (Gaussian) noise fluctuations, this evidence is below 1-$\sigma$. The tightest constraint on the time delay is $<0.51$ ms (90% C.L.) from GW$200311_115853$. From the non-observation of GW scrambling, we constrain the optical depth for LIB, accounting for the chance of randomly distributed lenses (eg. galaxies) along the line of sight. Our LIB constraints on a (quartic) scalar-tensor Horndeski theory are more stringent than solar system tests for a wide parameter range and comparable to GW170817 in some limits. Interpreting GW190521 as an AGN binary (i.e. taking an AGN flare as a counterpart) allows even more stringent constraints. Our results demonstrate the potential and high sensitivity achievable by tests of GR, based on GW lensing.

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S. Goyal, A. Vijaykumar, J. Ezquiaga, et. al.
Fri, 13 Jan 23
41/72

Comments: 18 pages, 10 figures

Performance of an ultra-pure NaI(Tl) detector produced by an indigenously-developed purification method and crystal growth for the COSINE-200 experiment [CL]

Posted on by

http://arxiv.org/abs/2301.04884


The COSINE-100 experiment has been operating with 106 kg of low-background NaI(Tl) detectors to test the results from the DAMA/LIBRA experiment, which claims to have observed dark matter. However, since the background of the NaI(Tl) crystals used in the COSINE-100 experiment is 2-3 times higher than that in the DAMA detectors, no conclusion regarding the claimed observation from the DAMA/LIBRA experiment could be reached. Therefore, we plan to upgrade the current COSINE-100 experiment to the next phase, COSINE-200, by using ultra-low background NaI(Tl) detectors. The basic principle was already proved with the commercially available Astro-grade NaI powder from Sigma-Aldrich company. However, we have developed a mass production process of ultra-pure NaI powder at the Center for Underground Physics (CUP) of the Institute for Basic Science (IBS), Korea, using the direct purification of the raw NaI powder. We plan to produce more than 1,000 kg of ultra-pure powder for the COSINE200 experiment. With our crystal grower installed at CUP, we have successfully grown a low-background crystal using our purification technique for the NaI powder. We have assembled a low-background NaI(Tl) detector. In this article, we report the performance of this ultra-pure NaI(Tl) crystal detector produced at IBS, Korea.

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H. Lee, B. Park, J. Choi, et. al.
Fri, 13 Jan 23
52/72

Comments: N/A

Slowly rotating Kerr metric derived from the Einstein equations in affine-null coordinates [CL]

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http://arxiv.org/abs/2301.05092


Using a quasi-spherical approximation of an affine-null metric adapted to an asymptotic Bondi inertial frame, we present high order approximations of the metric functions in terms of the specific angular momentum for a slowly rotating stationary and axi-symmetric vacuum spacetime. The metric is obtained by following the procedure of integrating the hierarchy of Einstein equations in a characteristic formulation utilizing master functions for the perturbations. It is further verified its equivalence with the Kerr metric in the slowly rotation approximation by carrying out an explicit transformation between the Boyer-Lindquist coordinates to the employed affine-null coordinates.

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T. Mädler and E. Gallo
Fri, 13 Jan 23
56/72

Comments: N/A

Running vacuum in FLRW spacetime: The dynamics of $ρ_{\rm vac}(H)$ from the quantized matter fields [CL]

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http://arxiv.org/abs/2301.05205


Phenomenological work in the last few years has provided significant support to the idea that the vacuum energy density (VED) is a running quantity with the cosmological evolution and that this running helps to alleviate the cosmological tensions afflicting the $\Lambda$CDM. On the theoretical side, recent devoted studies have shown that the properly renormalized $\rho_{\rm vac}$ in FLRW spacetime adopts the “running vacuum model” (RVM) form. While in three previous studies by two of us (CMP and JSP) such computations focused solely on scalar fields non-minimally coupled to gravity, in the present work we compute the spin-$1/2$ fermionic contributions and combine them both. The calculation is performed using a new version of the adiabatic renormalization procedure based on subtracting the UV divergences at an off-shell renormalization point $M$. The quantum scaling of $\rho_{\rm vac}$ with $M$ turns into cosmic evolution with the Hubble rate, $H$. As a result the “cosmological constant” $\Lambda$ appears in our framework as the nearly sustained value of $8\pi G(H)\rho_{\rm vac}(H)$ around (any) given epoch $H$, where $G(H)$ is the gravitational coupling, which is also running, although very mildly (logarithmically). We find that the VED evolution at present reads $\delta \rho_{\rm vac}(H)\sim \nu_{\rm eff} m_{\rm Pl}^2 \left(H^2-H_0^2 \right)\ (|\nu_{\rm eff}|\ll 1)$. The coefficient $\nu_{\rm eff}$ receives contributions from all the quantized fields, bosons and fermions. Remarkably, there also exist higher powers ${\cal O}(H^{6})$ which can trigger inflation in the early universe. Finally, the equation of state (EoS) of the vacuum receives also quantum corrections from bosons and fermion fields, shifting its value from -1. The remarkable consequence is that the EoS of the quantum vacuum may nowadays effectively look like quintessence.

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C. Moreno-Pulido, J. Peracaula and S. Cheraghchi
Fri, 13 Jan 23
58/72

Comments: LaTex, 67 pages

Shadows of Kerr-Vaidya-like black holes [CL]

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http://arxiv.org/abs/2301.04967


In this work, we study the shadow boundary curves of rotating time-dependent black hole solutions which have well-defined Kerr and Vaidya limits. These solutions are constructed by applying the Newman-Janis algorithm to a spherically symmetric seed metric conformal to the Vaidya solution with a mass function that is linear in Eddington-Finkelstein coordinates. Equipped with a conformal Killing vector field, this class of solution exhibits separability of null geodesics, thus allowing one to develop an analytic formula for the boundary curve of its shadow. We find a simple power law describing the dependence of the mean radius and asymmetry factor of the shadow on the accretion rate. Applicability of our model to recent Event Horizon Telescope observations of M87${}^$ and Sgr A${}^$ is also discussed.

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H. Tan
Fri, 13 Jan 23
64/72

Comments: 22 pages

Ghost and Laplacian Instabilities in the Teleparallel Horndeski Gravity [CL]

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http://arxiv.org/abs/2301.04457


Teleparallel geometry offers a platform on which to build up theories of gravity where torsion rather than curvature mediates gravitational interaction. The teleparallel analogue of Horndeski gravity is an approach to teleparallel geometry where scalar-tensor theories are considered in this torsional framework. Being teleparallel gravity of lower order in dynamics, this turns out to be more general than metric Horndeski gravity. In other words, the class of teleparallel Horndeski gravity models is much broader than the standard metric one. In this work, we explore constraints on this wide range of models coming from ghost and Laplacian instabilities. The aim is to limit pathological branches of the theory by fundamental considerations. It is possible to conclude that a very large class of models results physically viable.

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S. Capozziello, M. Caruana, J. Said, et. al.
Thu, 12 Jan 23
5/68

Comments: N/A

SIMPly add a dark photon [CL]

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http://arxiv.org/abs/2301.04513


Pions of a dark sector gauge group can be strongly interacting massive particle (SIMP) dark matter, produced by the freeze-out of $3 \to 2$ interactions, with naturally large self-interactions. We study if adding a dark photon to the set-up can do it all: i) maintain thermalization with the visible sector, ii) resonantly enhance the $3\to2$ interactions, thus allowing for a perturbative pion description, and iii) provide a velocity dependent self-interaction that can affect small scale structure formation. We find that this is marginally excluded, as the required kinetic mixing is too small to maintain thermal equilibrium with the SM. Dropping the small scale structure requirement iii), a viable setup is reproduced for dark charges of $\alpha_d = 0.01-1$ and a dark pion mass $m_\pi \geq 30$ MeV. Late time annihilations are non-negligible making the SIMP dark pion a bit WIMPy.

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P. Braat and M. Postma
Thu, 12 Jan 23
12/68

Comments: 17 pages, 14 pages appendices, 3 figures

Dark Matter Induced Nucleon Decay Signals in Mesogenesis [CL]

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http://arxiv.org/abs/2301.04165


We introduce and study the first class of signals that can probe the dark matter in Mesogenesis which will be observable at current and upcoming large volume neutrino experiments. The well-motivated Mesogenesis scenario for generating the observed matter-anti-matter asymmetry necessarily has dark matter charged under baryon number. Interactions of these particles with nuclei can induce nucleon decay with kinematics differing from sponanteous nucleon decay. We calculate the rate for this process and develop a simulation of the signal that includes important distortions due to nuclear effects. We estimate the sensitivity of DUNE, Super-Kamiokande, and Hyper-Kamiokande to this striking signal.

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J. Berger and G. Elor
Thu, 12 Jan 23
28/68

Comments: 6 pages, 3 figures, 4 tables. All data generated using this code is available upon request. The code itself can be downloaded from this https URL

Kinetic equilibrium of two-dimensional force-free current sheets [CL]

Posted on by

http://arxiv.org/abs/2301.04590


Force-free current sheets are local plasma structures with field-aligned electric currents and approximately uniform plasma pressures. Such structures, widely found throughout the heliosphere, are sites for plasma instabilities and magnetic reconnection, the growth rate of which is controlled by the structure’s current sheet configuration. Despite the fact that many kinetic equilibrium models have been developed for one-dimensional (1D) force-free current sheets, their two-dimensional (2D) counterparts, which have a magnetic field component normal to the current sheets, have not received sufficient attention to date. Here, using particle-in-cell simulations, we search for such 2D force-free current sheets through relaxation from an initial, magnetohydrodynamic equilibrium. Kinetic equilibria are established toward the end of our simulations, thus demonstrating the existence of kinetic force-free current sheets. Although the system currents in the late equilibrium state remain field aligned as in the initial configuration, the velocity distribution functions of both ions and electrons systematically evolve from their initial drifting Maxwellians to their final time-stationary Vlasov state. The existence of 2D force-free current sheets at kinetic equilibrium necessitates future work in discovering additional integrals of motion of the system, constructing the kinetic distribution functions, and eventually investigating their stability properties.

Read this paper on arXiv…

X. An, A. Artemyev, V. Angelopoulos, et. al.
Thu, 12 Jan 23
36/68

Comments: 20 pages, 12 figures

Reconstruction Methods and the Amplification of the Inflationary Spectrum [CL]

Posted on by

http://arxiv.org/abs/2301.04477


We analyze the consequences of different evolutions of the Hubble parameter on the spectrum of scalar inflationary perturbations. The analysis is restricted to inflationary phases described by a transient evolution, when uncommon features arise in the inflationary spectra which may lead to an amplitude enhancement. We then discuss how the spectrum is, respectively, amplified or blue-tilted in the presence or absence of a growing solution of the Mukhanov-Sasaki equation. The cases of general relativity with a minimally coupled inflaton and that of induced gravity are considered explicitly. Finally, some remarks on constant roll inflation are discussed.

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L. Chataignier, A. Kamenshchik, A. Tronconi, et. al.
Thu, 12 Jan 23
41/68

Comments: N/A

Particle-like solutions in the generalized SU(2) Proca theory [CL]

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http://arxiv.org/abs/2212.13832


The generalized SU(2) Proca theory is a vector-tensor modified gravity theory where the action is invariant under both diffeomorphisms and global internal transformations of the SU(2) group. This work constitutes the first approach to investigate the physical properties of the theory at astrophysical scales. We have found solutions that naturally generalize the particle-like solutions of the Einstein-Yang-Mills equations, also known as gauge boson stars. Under the requirement that the solutions must be static, asymptotically flat, and globally regular, the t’Hooft-Polyakov magnetic monopole configuration for the vector field rises as one viable possibility. The solutions have been obtained analytically through asymptotic expansions and numerically by solving the boundary value problem. We have found new features in the solutions such as regions with negative effective energy density and imaginary effective charge. We have also obtained a new kind of globally charged solutions for some region in the parameter space of the theory. Furthermore, we have constructed equilibrium sequences and found turning points in some cases. These results hint towards the existence of stable solutions which are absent in the Einstein-Yang-Mills case.

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J. Martinez, J. Rodriguez, Y. Rodriguez, et. al.
Thu, 12 Jan 23
51/68

Comments: LaTeX file in RevTeX 4.1 style, 20 pages, 11 figures

Distortion of neutrino oscillations by dark photon dark matter [CL]

Posted on by

http://arxiv.org/abs/2301.04152


A weakly coupled and light dark photon coupling to lepton charges $L_\mu-L_\tau$ is an intriguing dark matter candidate whose coherent oscillations alter the dispersion relations of leptons. We study how this effect modifies the dynamics of neutrino flavor conversions, focusing on atmospheric and solar oscillations. We analyze data from the T2K, SNO, and Super-Kamiokande experiments in order to obtain world-leading limits on the dark photon gauge coupling for masses below $\sim 10^{-11}\,\mathrm{eV}$. Degeneracies between shifts in the neutrino mass-squared differences and mixing angles and the new physics effect significantly relax the current constrains on the neutrino vacuum oscillation parameters.

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G. Alonso-Álvarez, K. Bleau and J. Cline
Thu, 12 Jan 23
68/68

Comments: 9 pages, 8 figures

Prototype Global Analysis of LISA Data with Multiple Source Types [CL]

Posted on by

http://arxiv.org/abs/2301.03673


The novel data analysis challenges posed by the Laser Interferometer Space Antenna (LISA) arise from the overwhelmingly large number of astrophysical sources in the measurement band and the density with which they are found in the data. Robust detection and characterization of the numerous gravitational wave sources in LISA data can not be done sequentially, but rather through a simultaneous global fit of a data model containing the full suite of astrophysical and instrumental features present in the data. While previous analyses have focused on individual source types in isolation, here we present the first demonstration of a LISA global fit analysis containing combined astrophysical populations. The prototype pipeline uses a blocked Metropolis Hastings algorithm to alternatingly fit to a population of ultra compact galactic binaries, known “verification binaries” already identified by electromagnetic observations, a population of massive black hole mergers, and an instrument noise model. The Global LISA Analysis Software Suite (GLASS) is assembled from independently developed samplers for the different model components. The modular design enables flexibility to future development by defining standard interfaces for adding new, or updating additional, components to the global fit without being overly prescriptive for how those modules must be internally designed. The GLASS pipeline is demonstrated on data simulated for the LISA Data Challenge 2b. Results of the analysis and a road-map for continued development are described in detail.

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T. Littenberg and N. Cornish
Wed, 11 Jan 23
26/80

Comments: 23 pages, 21 figures, submitted to Phys Rev D