Tag Archives: General Relativity and Quantum Cosmology

Searching for candidates of coalescing binary black holes formed through chemically homogeneous evolution in GWTC-3 [HEAP]

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http://arxiv.org/abs/2211.05945


The LIGO, Virgo, and KAGRA (LVK) collaboration has announced 90 coalescing binary black holes (BBHs) with $p_{\rm astro} > 50\%$ to date, however, the origin of their formation channels is still an open scientific question. Given various properties of BBHs (BH component masses and individual spins) inferred using the default priors by the LVK, independent groups have been trying to explain the formation of the BBHs with different formation channels. Of all formation scenarios, the chemically homogeneous evolution (CHE) channel has stood out with distinguishing features, namely, nearly-equal component masses and preferentially high individual spins aligned with the orbital angular momentum. We perform Bayesian inference on the BBH events officially reported in GWTC-3 with astrophysically-predicted priors representing different formation channels of the isolated binary evolution (CEE: common-envelope evolution channel; CHE; SMT: stable mass transfer). Given assumed models, we report strong evidence for GW190517_055101 being most likely to have formed through the CHE channel. Assuming the BBH events in the subsample are all formed through one of the isolated binary evolution channels, we obtain the lower limits on the local merger rate density of these channels at $11.45 ~\mathrm{Gpc^{-3}~yr^{-1}}$ (CEE), $0.18 ~\mathrm{Gpc^{-3}~yr^{-1}}$ (CHE), and $0.63 ~\mathrm{Gpc^{-3}~yr^{-1}}$ (SMT) at $90\%$ credible level.

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Y. Qin, Y. Wang, S. Bavera, et. al.
Mon, 14 Nov 22
55/69

Comments: 13 pages, 4 figures. Accepted for publication in ApJ

Constraints on ultra-slow-roll inflation from the third LIGO-Virgo observing run [CEA]

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http://arxiv.org/abs/2211.05386


The nonattractor evolution in ultra-slow-roll (USR) inflation results in the amplification of superhorizon curvature perturbations and then induces a strong and detectable stochastic gravitational wave background. In this letter, we search for such a stochastic gravitational wave background in data from the third LIGO-Virgo observing run and place constraints on the USR inflationary models. The $e$-folding number of the USR phase are constrained to be $\Delta N \lesssim 2.9$ at the 95% confidence level and the power spectrum of curvature perturbations amplified during the USR phase is constrained to be $\log_{10}P_{R\mathrm{p}}<-1.7$ at the scales $2.9\times10^5 ~\mathrm{pc^{-1}} \lesssim k \lesssim 1.7\times10^{11}~\mathrm{pc^{-1}}$. Besides, we forecast the ability of future experiments to constrain USR inflation, and find $P_{R\mathrm{p}}\lesssim 10^{-3.6}$ for LISA and Taiji, $P_{R\mathrm{p}}\lesssim 10^{-3.3}$ for Cosmic Explore and Einstein Telescope, $P_{R\mathrm{p}}\lesssim 10^{-5.5}$ for DECIGO and Big Bang Observer and $P_{R\mathrm{p}}\lesssim 10^{-5.2}$ for Square Kilometre Array.

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B. Mu, G. Cheng, J. Liu, et. al.
Fri, 11 Nov 22
4/58

Comments: 6 pages, 3 figures

No Smooth Spacetime in Lorentzian Quantum Cosmology and Trans-Planckian Physics [CL]

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http://arxiv.org/abs/2211.05306


In minisuperspace quantum cosmology, the Lorentzian path integral formulations of the no-boundary and tunneling proposals have recently been analyzed. But it has been pointed out that the wave function of linearized perturbations around a homogeneous and isotropic background is of an inverse Gaussian form and thus that their correlation functions are divergent. In this paper, we revisit this issue and consider the problem of perturbations in Lorentzian quantum cosmology by modifying the dispersion relation based on trans-Planckian physics. We consider two modified dispersion relations, the generalized Corley-Jacobson dispersion relation with higher momentum terms and the Unruh dispersion relation with a trans-Planckian mode cut-off, as examples. We show that the inverse Gaussian problem of perturbations in Lorentzian quantum cosmology is hard to overcome with the trans-Planckian physics modifying the dispersion relation at short distances.

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H. Matsui, S. Mukohyama and A. Naruko
Fri, 11 Nov 22
6/58

Comments: 24 pages, 11 figures

Dark energy by natural evolution: Constraining dark energy using Approximate Bayesian Computation [CEA]

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http://arxiv.org/abs/2211.05482


We look at dark energy from a biology inspired viewpoint by means of the Approximate Bayesian Computation (ABC) and late time cosmological observations. We find that dynamical dark energy comes out on top, or in the ABC language naturally selected, over the standard $\Lambda$CDM cosmological scenario. We confirm this conclusion is robust to whether baryon acoustic oscillations and Hubble constant priors are considered. Our results show that the algorithm prefers low values of the Hubble constant, consistent or at least a few standard deviation away from the cosmic microwave background estimate, regardless of the priors taken initially in each model. This supports the result of the traditional MCMC analysis and could be viewed as strengthening evidence for dynamical dark energy being a more favorable model of late time cosmology.

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R. Bernardo, D. Grandón, J. Said, et. al.
Fri, 11 Nov 22
7/58

Comments: 22 pages, 14 figures, 4 tables, comments welcome

Snowmass Theory Frontier Report [CL]

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http://arxiv.org/abs/2211.05772


This report summarizes the recent progress and promising future directions in theoretical high-energy physics (HEP) identified within the Theory Frontier of the 2021 Snowmass Process.

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N. Craig, C. Csáki, A. El-Khadra, et. al.
Fri, 11 Nov 22
23/58

Comments: N/A

Comparing Accretion Disks and Dark Matter Spikes in Intermediate Mass Ratio Inspirals [CL]

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http://arxiv.org/abs/2211.05145


Intermediate Mass Ratio Inspirals (IMRIs) will be observable with space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA). To this end, the environmental effects in such systems have to be modeled and understood. These effects can include (baryonic) accretion disks and dark matter (DM) overdensities, so called spikes. For the first time, we model an IMRI system with both an accretion disk and a DM spike present and compare their effects on the inspiral and the emitted gravitational wave signal. We study the eccentricity evolution, employ the braking index and derive the dephasing index, which turn out to be complementary observational signatures. They allow us to disentangle the accretion disk and DM spike effects in the IMRI system.

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N. Becker and L. Sagunski
Fri, 11 Nov 22
30/58

Comments: 16 pages, 8 figures. Comments are welcome. Code available online at this http URL

The effects of dark energy on the propagation of gravitational waves [CL]

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http://arxiv.org/abs/2211.05760


Dark energy can be modeled as an effective energy-momentum tensor (EMT) in the Einstein’s equations, responsible for the acceleration of the Universe. Using this effective approach, we derive a model independent equation for the propagation of gravitation waves (GW) in terms of an effective GW speed $c_T$, showing that it can depend on polarization, time and space, and is related to the anisotropy of the dark energy EMT. A similar result is derived in moment space, in terms of an appropriately defined momentum effective sound speed $\tilde{c}_T$. The friction term depends on $\tilde{c}’_T/\tilde{c}_T$, and can be expressed in terms of an effective frequency dependent scale factor.
The modification of the friction term induces a frequency dependent difference between GW and electromagnetic luminosity distance, given by the relation $d_L^{GW}(z)=\tilde{c}_T(z)\, d_L^{EM}(z)$. We discuss the implications for constraining dark energy models and modified gravity theories with GW luminosity distance observations, using bright and dark sirens.

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A. Romano
Fri, 11 Nov 22
31/58

Comments: N/A

Needle in a Bayes Stack: a Hierarchical Bayesian Method for Constraining the Neutron Star Equation of State with an Ensemble of Binary Neutron Star Post-merger Remnants [HEAP]

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http://arxiv.org/abs/2211.05250


Binary neutron star (BNS) post-merger gravitational-wave emission can occur in the aftermath of a BNS merger — provided the system avoids prompt collapse to a black hole — as a quasistable hypermassive remnant experiences quadrupolar oscillations and non-axisymmetric deformations. The post-merger gravitational-wave spectrum possesses a characteristic peak frequency that has been shown to be dependent on the binary chirp mass and the neutron star equation of state (EoS), rendering post-merger gravitational waves a powerful tool for constraining neutron star composition. Unfortunately, the BNS post-merger signal is emitted at high ($\gtrsim 1.5$ kHz) frequencies, where ground-based gravitational wave detectors suffer from reduced sensitivity. It is therefore unlikely that post-merger signals will be detected with sufficient signal-to-noise ratio (SNR) until the advent of next-generation detectors. However, by employing empirical relations derived from numerical relativity simulations, we can combine information across an ensemble of BNS mergers, allowing us to obtain EoS constraints with many low-SNR signals. We present a hierarchical Bayesian method for deriving constraints on $R_{1.6}$, the radius of a 1.6$\mathrm{M_{\odot}}$ neutron star, through an ensemble analysis of binary neutron star mergers. We apply this method to simulations of the next two LIGO-Virgo-KAGRA observing runs, O4 and O5, as well as an extended 4-year run at A+ sensitivity, demonstrating the potential of our approach to yield EoS information from the post-merger signal with current-generation detectors. The A+ 4-year scenario is predicted to improve the constraint on $R_{1.6}$ from the currently available multimessenger-based 95% C.I. uncertainty of $R_{1.6}=12.07^{+0.98}{-0.77}$ km to $R{1.6}=11.91^{+0.80}_{-0.56}$ km, a 22% reduction of the 95% C.I. width.

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A. Criswell, J. Miller, N. Woldemariam, et. al.
Fri, 11 Nov 22
36/58

Comments: 21 pages, 15 figures, 4 tables; submitting to PRD

Gauge-invariant perturbations at a quantum gravity bounce [CL]

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http://arxiv.org/abs/2211.04500


We study the dynamics of gauge-invariant scalar perturbations in cosmological scenarios with a modified Friedmann equation, such as quantum gravity bouncing cosmologies. We work within a separate universe approximation which captures wavelengths larger than the cosmological horizon; this approximation has been successfully applied to loop quantum cosmology and group field theory. We consider two variables commonly used to characterise scalar perturbations: the curvature perturbation on uniform-density hypersurfaces $\zeta$ and the comoving curvature perturbation $\mathcal{R}$. For standard cosmological models in general relativity as well as in loop quantum cosmology, these quantities are conserved and equal on super-horizon scales for adiabatic perturbations. Here we show that while these statements can be extended to a more general form of modified Friedmann equations similar to that of loop quantum cosmology, in other cases, such as the simplest group field theory bounce scenario, $\zeta$ is conserved across the bounce whereas $\mathcal{R}$ is not. We relate our results to approaches based on a second order equation for a single perturbation variable, such as the Mukhanov-Sasaki equation.

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S. Gielen and L. Mickel
Fri, 11 Nov 22
38/58

Comments: 26 pages, 6 figures

Cosmological impact of microwave background temperature measurements [CEA]

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http://arxiv.org/abs/2211.05377


The cosmic microwave background temperature is a cornerstone astrophysical observable. Its present value is tightly constrained, but its redshift dependence, which can now be determined until redshift $z\sim6.34$, is also an important probe of fundamental cosmology. We show that its constraining power is now comparable to that of other background cosmology probes, including Type Ia supernovae and Hubble parameter measurements. We illustrate this with three models, each based on a different conceptual paradigm, which aim to explain the recent acceleration of the universe. We find that for parametric extension of $\Lambda$CDM the combination of temperature and cosmological data significantly improves constraints on the model parameters, while for alternative models without a $\Lambda$CDM limit this data combination rules them out.

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L. Gelo, C. Martins, N. Quevedo, et. al.
Fri, 11 Nov 22
50/58

Comments: 9 pages, 4 figures; Phys. Lett. B (in press)

Primordial Black Holes [CEA]

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http://arxiv.org/abs/2211.05767


We review aspect of primordial black holes, i.e., black holes which have been formed in the early Universe. Special emphasis is put on their formation, their r\^ole as dark matter candidates and their manifold signatures, particularly through gravitational waves.

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A. Escrivà, F. Kuhnel and Y. Tada
Fri, 11 Nov 22
51/58

Comments: 117 pages, 39 figures, 555 references; to appear as invited book chapter in “Listening to the dark Universe: black holes in the era of gravitational-wave astronomy”; comments warmly welcome

The Big Bang could be anisotropic. The case of Bianchi I model [CL]

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http://arxiv.org/abs/2211.05664


We consider an evolution of anisotropic cosmological model on the example of the Bianchi type I homogeneous universe. It is filled by the mixture of matter and dark energy with an arbitrary barotropic equation of state (EoS). The general solution for this case is found and analyzed. A complete list of possible future singularities for this model is given. Some new solution were obtained for a particular EoSs, e.g. for the Bianchi type I {\Lambda}CDM homogeneous model. It is shown that all special cases corresponding to different EoSs have common properties, provided that now or at another moment of time the Universe is expanding, and the density of the mixture is positive. Then the evolution always begins with an anisotropic “Big Bang” which happened a finite time ago. After that the universe is constantly expanding and, in all cases, with rare exceptions, becomes more isotropic. A particularly strong isotropization is associated with the epoch of inflation. After its completion, the expansion of the universe becomes almost isotropic, and this case cannot be distinguished from isotropic by astronomical observations. This fact allows us to consider an anisotropic cosmological model as a possible candidate for the description of the observed Universe despite the isotropic pattern of expansion.

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S. Parnovsky
Fri, 11 Nov 22
56/58

Comments: 15 pages, no figures

The Hubble Tension and Early Dark Energy [CEA]

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http://arxiv.org/abs/2211.04492


Over the past decade, the disparity between the value of the cosmic expansion rate directly determined from measurements of distance and redshift or instead from the standard $\Lambda$CDM cosmological model calibrated by measurements from the early Universe, has grown to a level of significance requiring a solution. Proposed systematic errors are not supported by the breadth of available data (and “unknown errors” untestable by lack of definition). Simple theoretical explanations for this “Hubble tension” that are consistent with the majority of the data have been surprisingly hard to come by, but in recent years, attention has focused increasingly on models that alter the early or pre-recombination physics of $\Lambda$CDM as the most feasible. Here, we describe the nature of this tension, emphasizing recent developments on the observational side. We then explain why early-Universe solutions are currently favored and the constraints that any such model must satisfy. We discuss one workable example, early dark energy, and describe how it can be tested with future measurements. Given an assortment of more extended recent reviews on specific aspects of the problem, the discussion is intended to be fairly general and understandable to a broad audience.

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M. Kamionkowski and A. Riess
Thu, 10 Nov 22
2/78

Comments: 34 pages, 8 figures. Invited Review for Ann. Rev. Nucl. Part. Sci

Axial Bianchi IX and its Lema{î}tre-Hubble diagram [CL]

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http://arxiv.org/abs/2211.04844


We compute the Lema{\^i}tre-Hubble diagram for axial Bianchi IX universes with comoving dust. We motivate our choice by defining a {\it minimal} symmetry breaking of the cosmological principle. This criterium admits only two possibilities: the axial Bianchi I and IX universes. The latter have positive curvatures and reduce to the former in the zero curvature limit. Remarkably, negative curvatures are excluded by this minimal symmetry breaking in presence of comoving dust.

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G. Valent, A. Tilquin and T. Schücker
Thu, 10 Nov 22
15/78

Comments: 42 pages, 2 figures

Back and Forth: Reverse Phase Transitions in Numerical Relativity Simulations [CL]

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http://arxiv.org/abs/2211.04662


Multi-messenger observations of binary neutron star mergers provide a unique opportunity to constrain the dense-matter equation of state. Although it is known from quantum chromodynamics that hadronic matter will undergo a phase transition to exotic forms of matter, e.g., quark matter, the onset density of such a phase transition cannot be computed from first principles. Hence, it remains an open question if such phase transitions occur inside isolated neutron stars or during binary neutron star mergers, or if they appear at even higher densities that are not realized in the Cosmos. In this article, we perform numerical-relativity simulations of neutron-star mergers and investigate scenarios in which the onset density of such a phase transition is exceeded in at least one inspiralling binary component. Our simulations reveal that shortly before the merger it is possible that such stars undergo a “reverse phase transition”, i.e., densities decrease and the quark core inside the star disappears leaving a purely hadronic star at merger. After the merger, when densities increase once more, the phase transition occurs again and leads, in the cases considered in this work, to a rapid formation of a black hole. We compute the gravitational-wave signal and the mass ejection for our simulations of such scenarios and find clear signatures that are related to the postmerger phase transition, e.g., smaller ejecta masses due to the softening of the equation of state through the quark core formation. Unfortunately, we do not find measurable imprints of the reverse phase transition.

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M. Ujevic, H. Gieg, F. Schianchi, et. al.
Thu, 10 Nov 22
41/78

Comments: 12 pages, 8 figures

Warm Inflation in $f(R,T)$ gravity [CL]

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http://arxiv.org/abs/2211.05059


In this work, we explored warm inflation in the background of $f(R,T)$ gravity in the strong dissipation regime. Considering scalar field for FLRW universe, we derived modified field equations. We then deduced slow-roll parameters under slow-roll approximations followed by power spectrum for scalar and tensor perturbations and their corresponding spectral indices. We have considered Chaotic and Natural potentials and estimated scalar spectral index and tensor-to-scalar ratio for constant as well as variable dissipation factor $\Gamma$. We found that both the rejected potentials can be revived under the context of $f(R,T)$ gravity with suitable choice of the model parameters. Further, it is seen that within the warm inflationary scenario both the potentials are consistent with Planck 2018 bounds at the Planckian and sub Planckian energy scales.

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B. Deb, S. Yeasmin and A. Deshamukhya
Thu, 10 Nov 22
47/78

Comments: 19 pages, 5 figures

INPOP Planetary ephemerides and applications in the frame of the BepiColombo mission including new constraints on the graviton mass and dilaton parameters [CL]

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http://arxiv.org/abs/2211.04881


We present here the new results obtained with the INPOP planetary ephemerides and BepiColombo radio-science simulations. We give new constraints for the classic General Relativity tests in terms of violation of the PPN parameters $\beta$ and $\gamma$ and the time variation of the gravitational constant G. We also present new limits for the mass of the graviton and finally we obtain new acceptable intervals for the dilaton parameters $\alpha_{0}$, $\alpha_{T}$ and $\alpha_{G}$. Besides these tests of gravitation, we also study the possibility of detecting the Sun core rotation.

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A. Fienga, L. Bernus, O. Minazzoli, et. al.
Thu, 10 Nov 22
51/78

Comments: arXiv admin note: substantial text overlap with arXiv:2111.04499

Gravitational wave constraints on spatial covariant gravities [CL]

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http://arxiv.org/abs/2211.04711


The direct discovery of gravitational waves (GWs) from the coalescence of compact binary components by the LIGO/Virgo/KAGRA Collaboration provides an unprecedented opportunity for exploring the underlying theory of gravity that drives the coalescence process in the strong and highly-dynamical field regime of gravity. In this paper, we consider the observational effects of spatial covariant gravities on the propagation of GWs in the cosmological background and obtain the observational constraints on coupling coefficients in the action of spatial covariant gravities from GW observations. We first decompose the GWs into the left-hand and right-hand circular polarization modes and derive the effects of the spatial covariant gravities on the propagation equation of GWs. We find that these effects can be divided into three classes: (1) frequency-independent effects on GW speed and friction, (2) parity-violating amplitude and velocity birefringences, and (3) Lorentz-violating damping rate and dispersion of GWs. With these effects, we calculate the corresponding modified waveform of GWs generated by the coalescence of compact binaries. By comparing these new effects with the publicly available posterior samples or results from various tests of gravities with LIGO/Virgo/KAGRA data in the literature, we derive the observational constraints on coupling coefficients of the spatial covariant gravities. These results represent the most comprehensive constraints on the spatial covariant gravities in the literature.

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T. Zhu, W. Zhao and A. Wang
Thu, 10 Nov 22
60/78

Comments: 14 pages, 2 figures, and 4 tables. arXiv admin note: text overlap with arXiv:2210.05259

Relativistic contributions to Mars rotation [EPA]

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http://arxiv.org/abs/2211.04937


Context: The orientation and rotation of Mars, which can be described by a set of Euler angles, is estimated from radioscience data and is then used to infer Mars internal properties. The data are analyzed using a modeling expressed within the Barycentric Celestial Reference System (BCRS).
Aims: We provide new and more accurate (to the $0.1$ mas level) estimations of the relativistic corrections to be included in the BCRS model of the orientation and rotation of Mars to avoid a misinterpretation of the data.
Methods: There are two types of relativistic contributions in Mars rotation and orientation: (i) those that directly impact the Euler angles and (ii) those resulting from the time transformation between a local Mars reference frame and BCRS. The former correspond essentially to the geodetic effect. We compute them assuming that Mars evolves on a Keplerian orbit. As for the latter, we compute the effect of the time transformation and compare the rotation angle corrections obtained using realistic orbits as described by ephemerides.
Results: The relativistic correction in longitude comes mainly from the geodetic effect and results in the geodetic precession (6.754mas/yr) and the geodetic annual nutation (0.565 mas amplitude). For the rotation angle, the correction is dominated by the effect of the time transformation. The main annual, semi-annual, and ter-annual terms have amplitudes of 166.954 mas, 7.783 mas, and 0.544mas, respectively. The amplitude of the annual term differs by about 9 mas from the estimate usually considered by the community. We identify new terms at the Mars-Jupiter and Mars-Saturn synodic periods (0.567 mas and 0.102 mas amplitude) that are relevant considering the current level of uncertainty of the measurements, as well as a contribution to the rotation rate (7.3088 mas/day). There is no significant correction that applies to the obliquity.

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R. Baland, A. Hees, M. Yseboodt, et. al.
Thu, 10 Nov 22
69/78

Comments: 15 pages, 7 figures, accepted for publication in A&A, InSight contribution ICN 304

SuperRad: A black hole superradiance gravitational waveform model [CL]

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http://arxiv.org/abs/2211.03845


Gravitational signatures of black hole superradiance are a unique probe of ultralight particles that are weakly-coupled to ordinary matter. The existence of an ultralight boson would lead spinning black holes with size comparable to the Compton wavelength of the boson to become superradiantly unstable to forming an oscillating cloud, spinning down the black hole, and radiating gravitational waves in the process. However, maximizing the chance of observing such signals or, in their absence, placing the strongest constraints on the existence of such particles, requires accurate theoretical predictions. In this work, we introduce a new gravitational waveform model, SuperRad, that models the dynamics, oscillation frequency, and gravitational wave signals of these clouds by combining numerical results in the relativistic regime with fits calibrated to analytical estimates, covering the entire parameter space of ultralight scalar and vector clouds with the lowest two azimuthal numbers ($m = 1$ and $2$). We present new calculations of the gravitational wave frequency evolution as the boson cloud dissipates, including using fully general-relativistic methods to quantify the error in more approximate treatments. Finally, as a first application, we assess the viability of conducting follow-up gravitational wave searches for ultralight vector clouds around massive black hole binary merger remnants. We show that LISA may be able to probe vector masses in the range from $1\times 10^{-16}$ eV to $6\times 10^{-16}$ eV using follow-up gravitational wave searches.

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N. Siemonsen, T. May and W. East
Wed, 9 Nov 22
2/76

Comments: 22 pages, 15 figures, code repository: www.bitbucket.org/weast/superrad

Impact of trans-Planckian quantum noise on the Primordial Gravitational Wave spectrum [CL]

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http://arxiv.org/abs/2211.04316


We investigate the impact of stochastic quantum noise due to trans–Planckian effects on the primordial power spectrum for gravity waves during inflation. Given an energy scale Lambda, expected to be close to the Planck scale m_Pl and larger than the Hubble scale H, this noise is described in terms of a source term in the evolution equation for comoving modes k which changes its amplitude growth from early times as long as the mode physical wavelength is smaller than Lambda^-1. We model the source term as due to a gas of black holes in the trans–Planckian regime and the corresponding Hawking radiation. In fact, for energy scales larger than, or of the order of Lambda, it is expected that trapped surfaces may form due to large energy densities. At later times the evolution then follows the standard sourceless evolution. We find that this mechanism still leads to a scale-invariant power spectrum of tensor perturbations, with an amplitude that depends upon the ratio Lambda/m_Pl.

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M. Cielo, G. Mangano and O. Pisanti
Wed, 9 Nov 22
11/76

Comments: 6 pages, 1 figure

Double-copy towards supergravity inflation with $α$-attractor models [CL]

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http://arxiv.org/abs/2211.04441


Key to the simplicity of supergravity alpha-attractor models of inflation are Volkov-Akulov fermions, often in the form of nilpotent superfields. Here we explore the possibility of using the double-copy to construct theories of Dirac-Born-Infeld-Volkov-Akulov (DBIVA) coupled to supergravity. A color-dual bootstrap admits scattering amplitudes involving pions and vectors through five-point tree-level order by order in mass-dimension, but requires the introduction of a tr(F^3) operator. Gauge theories with this operator were recently found to require a tower of higher-derivative operators to be compatible with the duality between color and kinematics. Adjoint-type double-copy construction at its most conservative seems to require the UV completion of DBVIA + pure Poincare supergravity scattering amplitudes to a family of theories involving DBVIA-like particles coupled to Weyl-Einstein supergravity. We also point out an alternative solution to color-dual gauged pions that allows adjoint double-copy without a tower of higher derivative corrections but at the cost of exchange symmetry between scalars.

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J. Carrasco, M. Lewandowski and N. Pavao
Wed, 9 Nov 22
20/76

Comments: 40 pages, 3 figures, 4 tables, ancillary data available at this url: this https URL

Spin effects in Spherical Harmonic Modes of Gravitational Waves from Eccentric Compact Binary Inspirals [CL]

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http://arxiv.org/abs/2211.04155


We compute the leading and sub-leading spin effects through the second post-Newtonian order (2PN) in spherical harmonic modes of gravitational waveforms from inspiralling compact binaries in non-circular orbits with non-precessing components. The two spin couplings, linear-in-spin (spin-orbit; SO) and quadratic-in-spin (spin-spin; SS), that appear in 2PN waveforms are computed with desired accuracy and explicit expressions for relevant modes are derived. The modes that have spin corrections through 2PN include $(\ell, |m|)$=$((2,2),\,(2,1),\,(3,3),\,(3,2),\,(3,1),\,(4,3),\,(4,1))$ modes. Closed form expressions for these modes for compact binaries in general orbits as well as in elliptical orbits are being provided. While the general orbit results can be used to study signals from binaries in orbits of arbitrary shape and nature, elliptical orbit results are applicable to systems with arbitrary eccentricities. We also express the elliptical orbit results as leading eccentric corrections to the circular results. Our prescription represents, the first, fully analytical treatment that combines spins, eccentricity and higher modes together and completes computation of spin effects through 2PN order. These should find immediate applications in inspiral-merger-ringdown modelling for eccentric mergers including the effect of non-precessing spins and higher modes as well as in parameter estimation analyses employing inspiral waveform.

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K. Paul and C. Mishra
Wed, 9 Nov 22
25/76

Comments: N/A

Photon Ring Astrometry for Superradiant Clouds [CL]

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http://arxiv.org/abs/2211.03794


Gravitational atoms produced from the superradiant extraction of rotational energy of spinning black holes can reach energy densities significantly higher than that of dark matter, turning black holes into powerful potential detectors for ultralight bosons. These structures are formed by coherently oscillating bosons, which induce oscillating metric perturbations, deflecting photon geodesics passing through their interior. The deviation of nearby geodesics can be further amplified near critical bound photon orbits. We discuss the prospect of detecting this deflection using photon ring autocorrelations with the Event Horizon Telescope and its next generation upgrade, which can probe a large unexplored region of the cloud mass parameter space when compared with previous constraints.

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Y. Chen, X. Xue, R. Brito, et. al.
Wed, 9 Nov 22
32/76

Comments: 9 pages, 5 figures

Exact formulations of relativistic electrodynamics and magnetohydrodynamics with helically coupled scalar field [HEAP]

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http://arxiv.org/abs/2211.03926


We present the general relativistic electrodynamics and magnetohydrodynamics with a helically coupled scalar field. We consider three component system with the fluid, scalar field and electromagnetic fields with the helical coupling. We derive three exact formulations: the covariant formulation, the ADM formulation, and the fully nonlinear and exact perturbation formulation. We also derive the weak-gravity limit with fully relativistic fluid and fields. The latter two formulations are presented in the cosmological context.

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J. Hwang and H. Noh
Wed, 9 Nov 22
39/76

Comments: 29 pages, no figure

Current data are consistent with flat spatial hypersurfaces in the $Λ$CDM cosmological model but favor more lensing than the model predicts [CEA]

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http://arxiv.org/abs/2211.04268


We study the performance of three pairs of tilted $\Lambda$CDM cosmological models, two pairs allowing for non-flat spatial hypersurfaces with CMB temperature and polarization power spectrum data (P18) from Planck, P18 lensing (lensing), and non-CMB data (non-CMB). For the six models, we measure cosmological parameters and study whether or not pairs of the data sets are mutually consistent in these models. Half of these models allow the lensing consistency parameter $A_L$ to be an additional free parameter, while the other three have $A_L = 1$. The tilted spatially-flat models assume the usual primordial spatial inhomogeneity power spectrum. The tilted non-flat models assume either the primordial power spectrum used in the Planck group analyses [Planck $P(q)$] or a recently computed power spectrum [new $P(q)$]. In the tilted non-flat models with $A_L=1$ we find differences between P18 data and non-CMB data cosmological parameter constraints, which are large enough to rule out the Planck $P(q)$ model at 3$\sigma$ but not the new $P(q)$ model. While both P18 data and non-CMB data separately favor a closed geometry when P18+non-CMB data are jointly analyzed the evidence in favor of non-flat hypersurfaces subsides. Differences between P18 data and non-CMB data cosmological constraints subside when $A_L$ is allowed to vary. From the most restrictive P18+lensing+non-CMB data combination we get almost model-independent constraints and find that the $A_L>1$ option is preferred over the $\Omega_k<0$ one, with the $A_L$ parameter, for all models, being larger than unity by $\sim 2.5\sigma$. According to the deviance information criterion, in the P18+lensing+non-CMB analysis, the varying $A_L$ option is on the verge of being strongly favored over the $A_L=1$ one, which could indicate a problem for the standard tilted flat $\Lambda$CDM model (Abridged abstract).

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J. Perez, C. Park and B. Ratra
Wed, 9 Nov 22
42/76

Comments: 83 pages, 39 figures

Tilted non-spatially-flat inflation [CEA]

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http://arxiv.org/abs/2211.02999


We construct non-linear inflaton potential energy densities that describe not-necessarily very-slowly-rolling closed and open inflation models, and compute tilted primordial spatial inhomogeneity power spectra that follow from quantum mechanical fluctuations during inflation in these models. These tilted power spectra differ from those that have previously been used to study cosmological data in non-flat cosmological models.

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B. Ratra
Tue, 8 Nov 22
1/79

Comments: 14 pages

Cosmic acceleration from topological considerations II: Fiber bundles [CL]

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http://arxiv.org/abs/1901.03354


In this work we study an alternative topological model for explaining the observed acceleration of space-time, we answer the question of whether this acceleration could be a consequence of the topology of the universe. For doing that, we propose that the whole universe is composed of a four dimensional base space, which represents space-time, endowed with a fiber forming a principal fiber bundle. We analyze this hypothesis for a homogeneous and isotropic four dimensional space-time and show that the effect of the fiber onto the base space is that the space-time accelerates depending on the group of the fiber, even in an oscillatory way, resembling the behavior of the universe according to recent observations. We conclude that there is the possibility of the accelerating behavior of the universe being due to its whole topology instead of an exotic kind of matter.

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M. Márquez, T. Chassin and P. Wiederhold
Tue, 8 Nov 22
14/79

Comments: 20 pages, 3 figures

Bernstein spectral method for quasinormal modes of a generic black hole spacetime and application to instability of dilaton-de Sitter solution [CL]

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http://arxiv.org/abs/2211.02997


We present the improved Mathematica code which computes quasinormal frequencies with the help of the Bernstein spectral method for a general class of black holes, allowing for asymptotically flat, de Sitter or anti-de Sitter asymptotic. The method is especially efficient when searching for purely imaginary modes and here it is used for detecting the instability region of a charged scalar field in the background of the charged asymptotically de Sitter dilatonic black hole. We show that the instability has superradiant nature and the dilaton field essentially influences the region of instability.

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R. Konoplya and A. Zhidenko
Tue, 8 Nov 22
17/79

Comments: 8 pages, 2 figures, revtex

The CGF dark matter fluid [CL]

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http://arxiv.org/abs/2211.02881


The cosmological gauge field (CGF) is a classical solution of SU(2)-weak gauge theory oscillating rapidly in time. It is the dark matter driving the CGF cosmology. A general, local, mathematically natural construction of the CGF is given here. The macroscopic properties are derived. The CGF is an irrotational perfect fluid. It provides a synchronized global time coordinate and a global rest frame. There is a conserved number density. The energy density and pressure are related by the same equation of state as derived in the CGF cosmology and used in the TOV stellar structure equations for stars made of CGF dark matter. The present construction justifies the TOV solution. Some possible routes towards testing the theory are suggested at the end.

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D. Friedan
Tue, 8 Nov 22
20/79

Comments: 15 pages. Details of calculations are in a note in the ancillary files

Pulsar Timing Response to Gravitational Waves from a Massive Compact Source [HEAP]

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http://arxiv.org/abs/2211.03349


Pulsar timing arrays (PTAs) are searching for nanohertz-frequency gravitational waves (GWs) through cross-correlation of pulse arrival times from a set of radio pulsars. PTAs have relied upon a frequency-shift formula of the pulse, where planar GWs are usually assumed. Phase corrections due to the wavefront curvature have been recently discussed. In this paper, we derive a frequency-shift formula for GWs from a compact source such as a binary of supermassive black holes, where the differences in the GW amplitude and direction between the Earth and the pulsar are examined in the quadrupole approximation. By using the new formula, effects beyond the plane-wave approximation are discussed and nearby relevant GW source candidates are also mentioned.

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R. Kubo, K. Yamahira and H. Asada
Tue, 8 Nov 22
21/79

Comments: 4 pages, 2 figures, submitted to ApJL

Quantum gravity and scale symmetry in cosmology [CL]

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http://arxiv.org/abs/2211.03596


We discuss predictions for cosmology which result from the scaling solution of functional flow equations for a quantum field theory of gravity. A scaling solution is necessary to render quantum gravity renormalizable. Our scaling solution is directly connected to the quantum effective action for the metric coupled to a scalar field. It includes all effects of quantum fluctuations and is invariant under general coordinate transformations. Solving the cosmological field equations derived by variation of the quantum effective action provides for a detailed quantitative description of the evolution of the universe. The \qq{beginning state} of the universe is found close to an ultraviolet fixed point of the flow equation. It can be described by an inflationary epoch, with approximate scale invariance of the observed primordial fluctuation spectrum explained by approximate quantum scale symmetry. Overall cosmology realizes a dynamical crossover from the ultraviolet fixed point to an infrared fixed point which is approached in the infinite future. Present cosmology is close to the infrared fixed point. It features dynamical dark energy mediated by a light scalar field. The tiny mass of this cosmon arises from its role as a pseudo Goldstone boson of spontaneously broken quantum scale symmetry. The extremely small value of the present dark energy density in Planck units results dynamically as a consequence of the huge age of the universe. The cosmological constant problem finds a dynamical solution. We present a detailed quantitative computation of the scaling solution for the scalar effective potential and the field-dependent coefficient of the curvature scalar. This allows for further quantitative predictions.

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C. Wetterich
Tue, 8 Nov 22
41/79

Comments: 31 pages, 2 figures

Search for Microlensing Signature in Gravitational Waves from Binary Black Hole Events [IMA]

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http://arxiv.org/abs/2211.02655


In a recent search (Kim et al. 2022), we looked for microlensing signature in gravitational waves from spectrograms of the binary black hole events in the first and second gravitational-wave transient catalogs. For the search, we have implemented a deep learning-based method (Kim et al. 2021) and figured out that one event, GW190707 093326, out of forty-six events, is classified into the lensed class. However, upon estimating the p-value of this event, we observed that the uncertainty of the p-value still includes the possibility of the event being unlensed. Therefore, we concluded that no significant evidence of beating patterns from the evaluated binary black hole events has found from the search. For a consequence study, we discuss the distinguishability between microlensed gravitational waves and the signal from precessing black hole binaries.

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K. Kim
Tue, 8 Nov 22
48/79

Comments: 2 pages, 1 figure, submitted for the proceeding of the IAU Symposium 368: Machine Learning in Astronomy

Gravitational wave astronomy: astrophysical and cosmological inferences [CL]

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http://arxiv.org/abs/2211.03142


We briefly discuss the most prominent results and specific sources detected by gravitational-wave observatories LIGO-Virgo during first three O1-O3 runs, as well as possible astrophysical and cosmological channels of their formation. We show that it is possible to explain the observed correlation between the effective spin of coalescing binary black holes and mass ratio of the components by accretion from the ambient medium onto primordial binary black holes. We also briefly discuss the recent results of searches for stochastic gravitational-wave background in the nano-Hz frequency band by pulsar timing arrays.

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K. Postnov and N. Mitichkin
Tue, 8 Nov 22
55/79

Comments: 10 pages, 1 figure, submitted to Proc. International Conference on Quantum Field Theory, High-Energy Physics, and Cosmology, JINR, Dubna, July 2022 (PEPAN Letters)

Primordial black holes and induced gravitational waves from double-pole inflation [CEA]

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http://arxiv.org/abs/2211.03523


The primordial black hole (PBH) productions from the inflationary potential with an inflection point usually rely heavily on the fine-tuning of the model parameters. We propose in this work a new kind of the $\alpha$-attractor inflation with asymmetric double poles that naturally lead to two periods of the standard slow-roll phases connected by a non-attractor ultra-slow-roll phase, during which the PBH productions are guaranteed without fine-tuning the model parameters. This double-pole inflation can be tested against the observational data in the future with rich phenomenological signatures: (1) the enhanced curvature perturbations at small scales admit a distinctive feature of ultraviolet oscillations in the power spectrum; (2) the quasi-monochromatic mass function of the produced PBHs can be made compatible to the asteroid-mass PBHs as the dominant dark matter component, the planet-mass PBHs as the OGLE ultrashort-timescale microlensing events, and the solar-mass PBHs as the LIGO events; (3) the induced gravitational waves can be detected by the gravitational-wave detectors in space and Pulsar Timing Array/Square Kilometer Array.

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C. Fu and S. Wang
Tue, 8 Nov 22
58/79

Comments: 5 pages + references, 6 figures

Directed search for continuous gravitational waves from the possible kilonova remnant G4.8+6.2 [HEAP]

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http://arxiv.org/abs/2211.02855


G4.8+6.2 was proposed as a possible kilonova remnant associated with the Korean guest star of AD 1163 in our Milky Way galaxy. Its age is about 860 years according to the historical record. If a neutron star was left in the center of G4.8+6.2, this young neutron star may radiate strong continuous gravitational waves, which could beat the indirect age-based upper limit with current LIGO sensitivity. In this work, we searched such continuous gravitational waves in the frequency band $20-1500 \mathrm{~Hz}$. This search used two days of LIGO O3b data from the Hanford and Livingston detectors. While no signal was found, we placed upper limits on the gravitational wave strain. For comparison we also showed the latest results of all-sky searches obtained with various search pipelines. With upgrading of the LIGO detectors, it will provide the opportunity to see whether a black hole or a neutron star is harbored inside G4.8+6.2.

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Y. Liu and Y. Zou
Tue, 8 Nov 22
63/79

Comments: 8 pages, 6 figures, 1 tables, Accepted for publication in Physical Review D

Quality over Quantity: Optimizing pulsar timing array analysis for stochastic and continuous gravitational wave signals [HEAP]

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http://arxiv.org/abs/2211.03201


The search for gravitational waves using Pulsar Timing Arrays (PTAs) is a computationally expensive complex analysis that involves source-specific noise studies. As more pulsars are added to the arrays, this stage of PTA analysis will become increasingly challenging. Therefore, optimizing the number of included pulsars is crucial to reduce the computational burden of data analysis. Here, we present a suite of methods to rank pulsars for use within the scope of PTA analysis. First, we use the maximization of the signal-to-noise ratio as a proxy to select pulsars. With this method, we target the detection of stochastic and continuous gravitational wave signals. Next, we present a ranking that minimizes the coupling between spatial correlation signatures, namely monopolar, dipolar, and Hellings & Downs correlations. Finally, we also explore how to combine these two methods. We test these approaches against mock data using frequentist and Bayesian hypothesis testing. For equal-noise pulsars, we find that an optimal selection leads to an increase in the log-Bayes factor two times steeper than a random selection for the hypothesis test of a gravitational wave background versus a common uncorrelated red noise process. For the same test but for a realistic EPTA dataset, a subset of 25 pulsars selected out of 40 can provide a log-likelihood ratio that is $89\%$ of the total, implying that an optimally selected subset of pulsars can yield results comparable to those obtained from the whole array. We expect these selection methods to play a crucial role in future PTA data combinations.

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L. Speri, N. Porayko, M. Falxa, et. al.
Tue, 8 Nov 22
66/79

Comments: N/A

Redshift drift cosmography with ELT and SKAO measurements [CEA]

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http://arxiv.org/abs/2211.02751


Mapping the expansion history of the universe is a compelling task of physical cosmology, especially in the context of the observational evidence for the recent acceleration of the universe, which demonstrates that canonical theories of cosmology and particle physics are incomplete and that there is new physics still to be discovered. Cosmography is a phenomenological approach to cosmology, where (with some caveats) physical quantities are expanded as a Taylor series in the cosmological redshift $z$, or analogous parameters such as the rescaled redshift $y=z/(1+z)$ or the logarithmic redshift $x=\ln{(1+z)}$. Moreover, the redshift drift of objects following cosmological expansion provides a model-independent observable, detectable by facilities currently under construction, {\it viz.} the Extremely Large Telescope and the Square Kilometre Array Observatory (at least in its full configuration). Here we use simulated redshift drift measurements from the two facilities to carry out an assessment of the cosmological impact and model discriminating power of redshift drift cosmography. We find that the combination of measurements from the two facilities can provide a stringent test of the $\Lambda$CDM paradigm, and that overall the logarithmic based expansions of the spectroscopic velocity drift are the most reliable ones, performing better than analogous expansions in the redshift or the rescaled redshift: the former nominally gives the smaller error bars for the cosmographic coefficients but is vulnerable to biases in the higher order terms (in other words, it is only reliable at low redshifts), while the latter always performs poorly.

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B. Rocha and C. Martins
Tue, 8 Nov 22
70/79

Comments: 18 pages, 5 figures, 5 tables; in press at MNRAS

Primordial Black Holes having Gravitomagnetic Monopole [HEAP]

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http://arxiv.org/abs/2211.03610


A primordial black hole (PBH) is thought to be made of the regular matter or ordinary mass ($M$) only, and hence could have already been decayed due to the Hawking radiation if its initial ordinary mass were $\lesssim 5 \times 10^{11}$ kg. Here, we study the role of gravitomagnetic monopole for the evaporation of PBHs, and propose that the lower energy PBHs (equivalent to ordinary mass $M << 5\times 10^{11}$ kg) could still exist in our present Universe, if it has gravitomagnetic monopole. If a PBH was initially made of both regular matter and gravitomagnetic monopole, the regular matter could decay away due to the Hawking radiation. The remnant gravitomagnetic monopole might not entirely decay, which could still be found as a PBH in the form of the pseudo `mass-energy’. If a PBH with $M \gtrsim 5 \times 10^{11}$ kg is detected, one may not be able to conclude if it has gravitomagnetic monopole. But, a plausible detection of a relatively low energy (equivalent to $2.176 \times 10^{-8}$ kg $< M \lesssim 5\times10^{11}$ kg) PBH in future may imply the existence of a gravitomagnetic monopole PBH, which may or may not contain the ordinary mass.

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C. Chakraborty and S. Bhattacharyya
Tue, 8 Nov 22
76/79

Comments: 6 pages, accepted for publication in Phys. Rev. D

Questions on calculation of primordial power spectrum with large spikes: the resonance model case [CEA]

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http://arxiv.org/abs/2211.02586


Inflationary models predicting a scale-dependent large amplification of the density perturbations have recently attracted a lot of attention because the amplified perturbations can seed a sizable amount of primordial black holes (PBHs) and stochastic background of gravitational waves (GWs). While the power spectra in these models are computed based on the linear equation of motion, it is not obvious whether loop corrections are negligible when such a large amplification occurs during inflation. In this paper, as a first step to discuss the loop corrections in such models, we use the in-in formalism and calculate the one-loop scalar power spectrum numerically and analytically in an illustrative model where the density perturbations are resonantly amplified due to oscillatory features in the inflaton potential. Our calculation is technically new in that the amplified perturbations are numerically taken into account in the in-in formalism for the first time. In arriving at our analytical estimates, we highlight the role that the Wronskian condition of perturbations, automatically satisfied in our model, plays in obtaining the correct estimates. In addition, the analytical estimates show that the contribution originating from the quantum nature of the perturbations in the loop can be dominant. We also discuss the necessary conditions for subdominant loop corrections in this model. We find that, for the typical parameter space leading to the $\mathcal O(10^7)$ amplification of the power spectrum required for a sufficient PBH production, the one-loop power spectrum dominates over the tree-level one, indicating the breakdown of the perturbation theory.

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K. Inomata, M. Braglia and X. Chen
Mon, 7 Nov 22
8/67

Comments: 42 pages, 15 figures

High Redshift $Λ$CDM Cosmology: To Bin or not to Bin? [CEA]

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http://arxiv.org/abs/2211.02129


We construct observational Hubble $H(z)$ and angular diameter distance $D_{A}(z)$ mock data with baseline Planck $\Lambda$CDM input values, before fitting the $\Lambda$CDM model to study evolution of probability density functions (PDFs) of best fit cosmological parameters $(H_0, \Omega_m, \Omega_k)$ across redshift bins. We find that PDF peaks only agree with the input parameters in low redshift ($z \lesssim 1$) bins for $H(z)$ and $D_{A}(z)$ constraints, and in all redshift bins when $H(z)$ and $D_{A}(z)$ constraints are combined. When input parameters are not recovered, we observe that PDFs exhibit non-Gaussian tails towards larger $\Omega_m$ values and shifts to (less pronounced) peaks at smaller $\Omega_m$ values. This flattening of the PDF is expected as $H(z)$ and $D_{A}(z)$ observations only constrain combinations of cosmological parameters at higher redshifts, so uniform PDFs are expected. Our analysis leaves us with a choice to bin high redshift data in the knowledge that we may be unlikely to recover Planck values, or conduct full sample analysis that biases $\Lambda$CDM inferences to the lower redshift Universe.

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E. Colgáin, M. Sheikh-Jabbari and R. Solomon
Mon, 7 Nov 22
15/67

Comments: 6 pages, 9 figures

Cosmological axion in post-Newtonian approximation [CL]

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http://arxiv.org/abs/2211.02197


We present first-order post-Newtonian (1PN) approximations of a general imperfect fluid and of an axion as a coherently oscillating massive scalar field, both in the cosmological context. For the axion, using the Klein transformation and Madelung transformation we derive the Schr\”odinger and Madelung hydrodynamic formulations, respectively, in exact covariant way and to 1PN order. Complete sets of equations for the 1PN formulations are derived without fixing the temporal gauge condition. We study the linear instability in cosmology and a static limit for both fluid and axion; these are presented independently of the gauge condition to 1PN order, thus are naturally gauge-invariant.

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J. Hwang and H. Noh
Mon, 7 Nov 22
24/67

Comments: 18 pages, no figure

Cosmic Topology I: Limits on Orientable Euclidean Manifolds from Circle Searches [CEA]

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http://arxiv.org/abs/2211.02603


The Einstein field equations of general relativity constrain the local curvature at every point in spacetime, but say nothing about the global topology of the Universe. Cosmic microwave background anisotropies have proven to be the most powerful probe of non-trivial topology since, within $\Lambda$CDM, these anisotropies have well-characterized statistical properties, the signal is principally from a thin spherical shell centered on the observer (the last scattering surface), and space-based observations nearly cover the full sky. The most generic signature of cosmic topology in the microwave background is pairs of circles with matching temperature and polarization patterns. No such circle pairs have been seen above noise in the WMAP or Planck temperature data, implying that the shortest non-contractible loop around the Universe through our location is longer than 98.5% of the comoving diameter of the last scattering surface. We translate this generic constraint into limits on the parameters that characterize manifolds with each of the nine possible non-trivial orientable Euclidean topologies, and provide a code which computes these constraints. In all but the simplest cases, the shortest non-contractible loop in the space can be shorter than the diameter of the last scattering surface by a factor ranging from 2 to at least 6. This result implies that a broader range of manifolds is observationally allowed than widely appreciated. Probing these manifolds will require subtler statistical signatures such as off-diagonal correlations of harmonic coefficients.

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P. Petersen, Y. Akrami, C. Copi, et. al.
Mon, 7 Nov 22
26/67

Comments: 14 pages, 7 figures

Post-inflationary GW production in generic higher (infinite) derivative gravity [CL]

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http://arxiv.org/abs/2211.02070


Gravity can be embedded into a renormalizable theory by means of adding quadratic in curvature terms. However, this at first leads to the presence of the Weyl ghost. It is possible to get rid of this ghost if the locality assumption is weakened and the propagator of the graviton is represented by an entire function of the d’Alembertian operator without new poles and zeros. Models of this type admit a cosmological solution describing the $R^2$, or Starobinsky, inflation. We study graviton production after inflation in this model and show that it is negligible despite the presence of the higher derivative operators which could potentially cause instabilities.

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A. Koshelev, A. Starobinsky and A. Tokareva
Mon, 7 Nov 22
33/67

Comments: We dedicate this paper to the memory of Valery Rubakov

Asymptotically flat vacuum solution for a rotating black hole in a modified gravity theory [CL]

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http://arxiv.org/abs/2203.07690


The theory of f(R)-gravity is one of the theories of modified Einstein gravity. The vacuum solution, on the other hand, of the field equation is the solution for black hole geometry. We establish here an asymptotically flat rotating black hole solution in an f(R)-gravity. This essentially leads to the modified solution to the Kerr black hole. This solution exhibits the change in fundamental properties of the black hole and its geometry. It particularly shows that radii of marginally stable and bound orbits and black hole event horizon increase compared to those in Einstein gravity, depending on the modified gravity parameter. It further argues for faster spinning black holes with spin (Kerr) parameter greater than unity, without any naked singularity. This supports the weak cosmic censorship hypothesis.

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A. Das and B. Mukhopadhyay
Mon, 7 Nov 22
41/67

Comments: 12 pages including 6 figures and 2 tables; some typos corrected; version published in European Physical Journal C (EPJC)

TDI noises transfer functions for LISA [CL]

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http://arxiv.org/abs/2211.02539


The LISA mission is the future space-based gravitational wave (GW) observatory of the European Space Agency. It is formed by 3 spacecraft exchanging laser beams in order to form multiple real and virtual interferometers. The data streams to be used in order to extract the large number and variety of GW sources are Time-Delay Interferometry (TDI) data. One important processing to produce these data is the TDI on-ground processing which recombines multiple interferometric on-board measurements to remove certain noise sources from the data such as laser frequency noise or spacecraft jitter. The LISA noise budget is therefore expressed at the TDI level in order to account for the different TDI transfer functions applied for each noise source and thus estimate their real weight on mission performance. In order to derive a usable form of these transfer functions, a model of the beams, the measurements, and TDI have been developed, and several approximation have been made. A methodology for such a derivation has been established, as well as verification procedures. It results in a set of transfer functions, which are now used by the LISA project, in particular in its performance model. Using these transfer functions, realistic noise curves for various instrumental configurations are provided to data analysis algorithms and used for instrument design.

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D. Nam, Y. Lemiere, A. Petiteau, et. al.
Mon, 7 Nov 22
57/67

Comments: 15 pages, 7 figures

Generalized Hilltop Inflation [CEA]

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http://arxiv.org/abs/2211.02426


We study a generalized version of hilltop inflation where the standard hilltop potential has been raised to a power and we allow fractional numbers for both the original hilltop power and the overall exponent. In the parameter space studied, the latter plays the major role in finding an agreement with the latest experimental constraint. Finally, we also find that the two characteristic mass scales of the inflaton potential differ by several orders of magnitude, indicating that a common fundamental origin is quite unlikely.

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H. Lillepalu and A. Racioppi
Mon, 7 Nov 22
66/67

Comments: 14 pages, 5 figures

Impact of multiple modes on the evolution of self-interacting axion condensate around rotating black holes [CL]

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http://arxiv.org/abs/2211.01949


Ultra-light particles, such as axions, form a macroscopic condensate around a highly spinning black hole by the superradiant instability. Due to its macroscopic nature, the condensate opens the possibility of detecting the axion through gravitational wave observations. However, the precise evolution of the condensate must be known for the actual detection. For future observation, we numerically study the influence of the self-interaction, especially interaction between different modes, on the evolution of the condensate in detail. First, we focus on the case when condensate starts with the smallest possible angular quantum number. For this case, we perform the non-linear calculation and show that the dissipation induced by the mode interaction is strong enough to saturate the superradiant instability, even if the secondary cloud starts with quantum fluctuations. Our result indicates that explosive phenomena such as bosenova do not occur in this case. We also show that the condensate settles to a quasi-stationary state mainly composed of two modes, one with the smallest angular quantum number for which the superradiant instability occurs and the other with the adjacent higher angular quantum number. We also study the case when the condensate starts with the dominance of the higher angular quantum number. We show that the dissipation process induced by the mode coupling does not occur for small gravitational coupling. Therefore, bosenova might occur in this case.

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H. Omiya, T. Takahashi, T. Tanaka, et. al.
Fri, 4 Nov 22
4/84

Comments: 29 pages, 25 figures, 1 table

Observational Signatures of Frame Dragging in Strong Gravity [CL]

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http://arxiv.org/abs/2211.01810


Objects orbiting in the presence of a rotating massive body experience a gravitomagnetic frame-dragging effect, known as the Lense-Thirring effect, that has been experimentally confirmed in the weak-field limit. In the strong-field limit, near the horizon of a rotating black hole, frame dragging becomes so extreme that all objects must co-rotate with the black hole’s angular momentum. In this work, we perform general relativistic numerical simulations to identify observable signatures of frame dragging in the strong-field limit that appear when infalling gas is forced to flip its direction of rotation as it is being accreted. In total intensity images, infalling streams exhibit “S”-shaped features due to the switch in the tangential velocity. In linear polarization, a flip in the handedness of spatially resolved polarization ticks as a function of radius encodes a transition in the magnetic field geometry that occurs due to magnetic flux freezing in the dragged plasma. Using a network of telescopes around the world, the Event Horizon Telescope collaboration has demonstrated that it is now possible to directly image black holes on event horizon scales. We show that the phenomena described in this work would be accessible to the next-generation Event Horizon Telescope (ngEHT) and extensions of the array into space, which would produce spatially resolved images on event horizon scales with higher spatial resolution and dynamic range.

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A. Ricarte, D. Palumbo, R. Narayan, et. al.
Fri, 4 Nov 22
13/84

Comments: Submitted to ApJL. 15 pages, 8 figures

Primordial non-gaussianity up to all orders: theoretical aspects and implications for primordial black hole models [CEA]

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http://arxiv.org/abs/2211.01728


We develop an exact formalism for the computation of the abundance of primordial black holes (PBHs) in the presence of local non-gaussianity (NG) in the curvature perturbation field. For the first time, we include NG going beyond the widely used quadratic and cubic approximations, and consider a completely generic functional form. Adopting threshold statistics of the compaction function, we address the computation of the abundance both for narrow and broad power spectra. While our formulas are generic, we discuss explicit examples of phenomenological relevance considering the physics case of the curvaton field. We carefully assess under which conditions the conventional perturbative approach can be trusted. In the case of a narrow power spectrum, this happens only if the perturbative expansion is pushed beyond the quadratic order (with the optimal order of truncation that depends on the width of the spectrum). Most importantly, we demonstrate that the perturbative approach is intrinsically flawed when considering broad spectra, in which case only the non-perturbative computation captures the correct result. Finally, we describe the phenomenological relevance of our results for the connection between the abundance of PBHs and the stochastic gravitational wave (GW) background related to their formation. As NGs modify the amplitude of perturbations necessary to produce a given PBHs abundance and boost PBHs production at large scales for broad spectra, modelling these effects is crucial to connect the PBH scenario to its signatures at current and future GWs experiments.

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G. Ferrante, G. Franciolini, A. Iovino, et. al.
Fri, 4 Nov 22
17/84

Comments: 29 pages + 12 figures

Gravitational wave stochastic background in reduced Horndeski theories [CL]

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http://arxiv.org/abs/2211.01405


We generalize to reduced Horndeski theories of gravity, where gravitational waves (GWs) travel at the speed of light, the expression of a statistically homogeneous and unpolarized stochastic gravitational wave background (SGWB) signal measured as the correlation between the individual signals detected by two interferometers in arbitrary configurations. We also discuss some results found in the literature regarding cosmological distances in modified theories, namely, the simultaneous validity of a duality distance relation for GW signals and of the coincidence between the gravitational wave luminosity distance, based on the energy flux, and the distance inferred from the wave amplitude. This discussion allows us to conclude that the spectral energy density per unit solid angle of an astrophysical SGWB signal has the same functional dependency with the luminosity of each emitting source as in General Relativity (GR). Using the generalized expression of the GW energy-momentum tensor and the modified propagation law for the tensor modes, we conclude that the energy density of a SGWB maintains the same functional relation with the scale factor as in GR, provided that the modified theory coincides with GR in a given hypersurface of constant time. However, the relation between the detected signal and the spectral energy density is changed by the global factor $G_4(\varphi(t_0))$, thus potentially serving as a probe for modified gravity theories.

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J. Lobato, I. Matos, M. Calvão, et. al.
Fri, 4 Nov 22
26/84

Comments: 10 pages

Scalarization [CL]

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http://arxiv.org/abs/2211.01766


Scalarization is a mechanism that endows strongly self-gravitating bodies, such as neutron stars and black holes, with a scalar field configuration. It resembles a phase transition in that the scalar configuration only appears when a certain quantity that characterizes the compact object, e.g., its compactness or spin, is beyond a threshold. We provide a critical and comprehensive review of scalarization, including the mechanism itself, theories that exhibit it, its manifestation in neutron stars, black holes, and their binaries, potential extension to other fields, and a thorough discussion of future perspectives.

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D. Doneva, F. Ramazanoğlu, H. Silva, et. al.
Fri, 4 Nov 22
27/84

Comments: 50 pages, 24 figures. Review commissioned by Reviews of Modern Physics, submitted version, comments welcome

Ultralight dark matter searches at the sub-Hz frontier with atom multi-gradiometry [CL]

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http://arxiv.org/abs/2211.01854


Single-photon atom gradiometry is a powerful experimental technique that can be employed to search for the oscillation of atomic transition energies induced by ultralight scalar dark matter (ULDM). In the sub-Hz regime the background is expected to be dominated by gravity gradient noise (GGN), which arises as a result of mass fluctuations around the experiment. In this work we model the GGN as surface Rayleigh waves and construct a likelihood-based analysis that consistently folds GGN into the sensitivity estimates of vertical atom gradiometers in the frequency window between 1 mHz and 1 Hz. We show that in certain geological settings GGN can be significantly mitigated when operating a multi-gradiometer configuration, which consists of three or more atom interferometers in the same baseline. Multi-gradiometer experiments, such as future versions of AION and MAGIS-100, have the potential to probe regions of scalar ULDM parameter space in the sub-Hz regime that have not been excluded by existing experiments.

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L. Badurina, V. Gibson, C. McCabe, et. al.
Fri, 4 Nov 22
46/84

Comments: 25 pages plus appendices, 10 figures, comments welcome

Performance of different correction maps in the extended phase-space method for spinning compact binaries [CL]

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http://arxiv.org/abs/2211.01880


Since the first detection of gravitational waves by the LIGO/VIRGO team, the related research field has attracted more attention. The spinning compact binaries system, as one of the gravitational-wave sources for broadband laser interferometers, has been widely studied by related researchers. In order to analyze the gravitational wave signals using matched filtering techniques, reliable numerical algorithms are needed. Spinning compact binaries systems in Post-Newtonian (PN) celestial mechanics have an inseparable Hamiltonian. The extended phase-space algorithm is an effective solution for the problem of this system. We have developed correction maps for the extended phase-space method in our previous work, which significantly improves the accuracy and stability of the method with only a momentum scale factor. In this paper, we will add more scale factors to modify the numerical solution in order to minimize the errors in the constants of motion. However, we find that these correction maps will result in a large energy bias in the subterms of the Hamiltonian in chaotic orbits, whose potential and kinetic energy, etc. are calculated inaccurately. We develop new correction maps to reduce the energy bias of the subterms of the Hamiltonian, which can instead improve the accuracy of the numerical solution and also provides a new idea for the application of the manifold correction in other algorithms.

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J. Luo, J. Feng, H. Zhang, et. al.
Fri, 4 Nov 22
48/84

Comments: N/A

On the superstring-inspired quantum correction to the Starobinsky model of inflation [CL]

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http://arxiv.org/abs/2211.01546


Superstring/M-theory is the theory of quantum gravity that can provide the UV-completion to viable inflation models. We modify the Starobinsky inflation model by adding the Bel-Robinson tensor $T^{\mu\nu\lambda\rho}$ squared term proposed as the leading quantum correction inspired by superstring theory. The $(R+\frac{1}{6m^2}R^2 -\frac{\beta}{8m^6}T^2)$ model under consideration has two parameters: the inflaton mass $m$ and the string-inspired positive parameter $\beta$. We derive the equations of motion in the Friedmann-Lemaitre-Robertson-Walker universe and investigate its solutions. We find the physical bounds on the value of the parameter $\beta$ by demanding the absence of ghosts and consistency of the derived inflationary observables with the measurements of the cosmic microwave background radiation.

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S. Ketov, E. Pozdeeva and S. Vernov
Fri, 4 Nov 22
55/84

Comments: 22 pages, 5 figures, LaTeX

Deep Residual Networks for Gravitational Wave Detection [CL]

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http://arxiv.org/abs/2211.01520


Traditionally, gravitational waves are detected with techniques such as matched filtering or unmodeled searches based on wavelets. However, in the case of generic black hole binaries with non-aligned spins, if one wants to explore the whole parameter space, matched filtering can become impractical, which sets severe restrictions on the sensitivity and computational efficiency of gravitational-wave searches. Here, we use a novel combination of machine-learning algorithms and arrive at sensitive distances that surpass traditional techniques in a specific setting. Moreover, the computational cost is only a small fraction of the computational cost of matched filtering. The main ingredients are a 54-layer deep residual network (ResNet), a Deep Adaptive Input Normalization (DAIN), a dynamic dataset augmentation, and curriculum learning, based on an empirical relation for the signal-to-noise ratio. We compare the algorithm’s sensitivity with two traditional algorithms on a dataset consisting of a large number of injected waveforms of non-aligned binary black hole mergers in real LIGO O3a noise samples. Our machine-learning algorithm can be used in upcoming rapid online searches of gravitational-wave events in a sizeable portion of the astrophysically interesting parameter space. We make our code, AResGW, and detailed results publicly available at https://github.com/vivinousi/gw-detection-deep-learning.

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P. Nousi, A. Koloniari, N. Passalis, et. al.
Fri, 4 Nov 22
71/84

Comments: 10 pages, 11 figures, code publicly available at this https URL

Efficient Gravitational Wave Searches with Pulsar Timing Arrays using Hamiltonian Monte Carlo [IMA]

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http://arxiv.org/abs/2211.01401


Pulsar timing arrays (PTAs) detect low-frequency gravitational waves (GWs) by looking for correlated deviations in pulse arrival times. Current Bayesian searches use Markov Chain Monte Carlo (MCMC) methods, which struggle to sample the large number of parameters needed to model the PTA and GW signals. As the data span and number of pulsars increase, this problem will only worsen. An alternative Monte Carlo sampling method, Hamiltonian Monte Carlo (HMC), utilizes Hamiltonian dynamics to produce sample proposals informed by first-order gradients of the model likelihood. This in turn allows it to converge faster to high dimensional distributions. We implement HMC as an alternative sampling method in our search for an isotropic stochastic GW background, and show that this method produces equivalent statistical results to similar analyses run with standard MCMC techniques, while requiring 100-200 times fewer samples. We show that the speed of HMC sample generation scales as $\mathcal{O}(N_\mathrm{psr}^{5/4})$ where $N_\mathrm{psr}$ is the number of pulsars, compared to $\mathcal{O}(N_\mathrm{psr}^2)$ for MCMC methods. These factors offset the increased time required to generate a sample using HMC, demonstrating the value of adopting HMC techniques for PTAs.

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G. Freedman, A. Johnson, R. Haasteren, et. al.
Fri, 4 Nov 22
76/84

Comments: 9 pages, 5 figures, submitted to Physical Review D

Prospects for a precise equation of state measurement from Advanced LIGO and Cosmic Explorer [HEAP]

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http://arxiv.org/abs/2211.01396


Gravitational-wave observations of neutron star mergers can probe the nuclear equation of state by measuring the imprint of the neutron star’s tidal deformability on the signal. We investigate the ability of future gravitational-wave observations to produce a precise measurement of the equation of state from binary neutron star inspirals. Since measurability of the tidal effect depends on the equation of state, we explore several equations of state that span current observational constraints. We generate a population of binary neutron stars as seen by a simulated Advanced LIGO-Virgo network, as well as by a planned Cosmic Explorer observatory. We perform Bayesian inference to measure the parameters of each signal, and we combine measurements across each population to determine $R_{1.4}$, the radius of a $1.4M_{\odot}$ neutron star. We find that with 321 signals the LIGO-Virgo network is able to measure $R_{1.4}$ to better than 2% precision for all equations of state we consider, however we find that achieving this precision could take decades of observation, depending on the equation of state and the merger rate. On the other hand we find that with one year of observation, Cosmic Explorer will measure $R_{1.4}$ to better than 0.6% precision. In both cases we find that systematic biases, such as from an incorrect mass prior, can significantly impact measurement accuracy and efforts will be required to mitigate these effects.

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D. Finstad, L. White and D. Brown
Fri, 4 Nov 22
77/84

Comments: 11 pages, 6 figures

Viscous attenuation of gravitational waves propagating through an inhomogeneous background [CL]

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http://arxiv.org/abs/2211.01652


We consider the propagation of gravitational waves in the late-time Universe, in the presence of structure, and we also consider the cosmic fluid to be viscous. In this work, we investigate the cumulative effect of inhomogeneities and viscosity of the cosmic-fluid, on the observables associated with the sources of the gravitational waves. Employing Buchert’s averaging procedure in the backreaction framework, we consider a model of inhomogeneous spacetime. Using the modified redshift versus distance relation, through the averaging process in the context of the model, we study the variation of the redshift-dependent part of the observed gravitational wave amplitude for different combinations of our model parameters, while simultaneously considering damping of the gravitational wave amplitude due to viscosity of the cosmic-fluid. Then, we investigate the differences occurring in the variation of the redshift-dependent part of the observed gravitational wave amplitude, due to consideration of viscous attenuation. We show that there are significant deviations after the inclusion of viscous attenuation in our analysis, depending on the chosen value of the coefficient of viscosity. Our result signifies the importance of the effect of viscosity, within the model of an inhomogeneous Universe, on precision measurements of parameters of compact-binary sources of gravitational waves.

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S. Pandey, A. Sarkar, A. Ali, et. al.
Fri, 4 Nov 22
83/84

Comments: 15 pages, 5 figures

Black hole perturbations in modified gravity theories [CL]

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http://arxiv.org/abs/2211.01103


The recent first detection of gravitational waves (GWs) from binary black hole mergers has spurred a renewed interest in possible deviations from General Relativity (GR), since they could be detected in the GWs emitted by such systems. Of particular interest is the ringdown phase of a binary black hole merger, which can be described by linear perturbations about a background stationary black hole solution. These perturbations mainly correspond to a superposition of ‘quasi-normal modes’ (QNMs), whose frequencies form a discrete set. One expects that modified gravity models could predict QNMs that differ from their GR counterpart: the detailed analysis of the GW signal represents an invaluable window to test GR and to look for specific signatures of modified gravity.
The work done in this thesis takes place in the context of scalar-tensor theories of gravity, and more particularly the Degenerate Higher-Order Scalar-Tensor theories. We start by a review of these theories and their properties, and describe a way to reformulate them in a framework with a clear geometrical interpretation. We then study linear perturbations about several existing nonrotating black hole solutions of such theories, and show why the perturbation equations obtained are very hard to decouple in general. When it is possible, in the case of odd parity perturbations, we describe the propagation of waves and relate it to the stability of the underlying spacetime. When it is not, we circumvent the difficulty by making use of an algorithm proposed recently in the mathematical literature that allows us to decouple the equations both at the black hole horizon and at infinity. This allows us to get the asymptotic behaviour of waves on such spacetimes, yielding valuable information that can allow us to rule some of them out. Finally, we use the asymptotic behaviours obtained to compute QNMs numerically.

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H. Roussille
Thu, 3 Nov 22
4/59

Comments: PhD thesis (defended 17/06/2022, Universit\’e Paris Cit\’e), 267 pages, 17 figures, 1 appendix, short introduction in French. Based on arXiv:2012.10218, arXiv:2103.14744, arXiv:2103.14750, arXiv:2204.04107, arXiv:2205.07746

Disks, spikes, and clouds: distinguishing environmental effects on BBH gravitational waveforms [CL]

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http://arxiv.org/abs/2211.01362


Future gravitational wave interferometers such as LISA, Taiji, DECIGO, and TianQin, will enable precision studies of the environment surrounding black holes. In this paper, we study intermediate and extreme mass ratio binary black hole inspirals, and consider three possible environments surrounding the primary black hole: accretion disks, dark matter spikes, and clouds of ultra-light scalar fields, also known as gravitational atoms. We present a Bayesian analysis of the detectability and measurability of these three environments. Focusing for concreteness on the case of a detection with LISA, we show that the characteristic imprint they leave on the gravitational waveform would allow us to identify the environment that generated the signal, and to accurately reconstruct its model parameters.

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P. Cole, G. Bertone, A. Coogan, et. al.
Thu, 3 Nov 22
7/59

Comments: 8 pages, 4 figures, 2 tables plus appendices

Dark energy and the fitting problem [CEA]

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http://arxiv.org/abs/2211.00756


At a global scale, the universe is generally fitted by an idealized manifold described by the FLRW metric. This is in particular the case when probing the universe to determine its dynamics. The process that fits the idealized manifold to the real universe is however not uniquely defined. This process may depend on the cosmic probe that has been used for the measurements, and could hence lead to different observed temporal evolutions of the scale factor. A correct interpretation of the observed accelerated expansion of the universe requires therefore first a thorough understanding of the fitting process that has been implicitly applied. In this article we establish the fitting processes for the SNIa, BAO and CMB cosmic probes, and deduce the related averaged Einstein equations. We demonstrate that the way these fittings have been applied in practice lead to an apparent dark energy effect. We also highlight the conceptual differences in the fitting processes between the SNIa and BAO probes on the one hand, and the CMB probe on the other hand. Considering those differences, we then show how the so-called Hubble tension can be explained.

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V. Deledicque
Thu, 3 Nov 22
8/59

Comments: 14 pages

Lorentz- and CPT-violating neutrinos from string/D-brane model [CL]

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http://arxiv.org/abs/2211.00900


We show that the space-time foam model from string/D-brane theory predicts a scenario in which neutrinos can possess linearly energy dependent speed variation, together with an asymmetry between neutrinos and antineutrinos, indicating the possibility of Lorentz and CPT symmetry violation for neutrinos. Such scenario is supported by a phenomenological conjecture from the possible associations of IceCube ultrahigh-energy neutrino events with the gamma-ray bursts. It is also consistent with the constraints set by the energy-losing decay channels~(e.g., $e^{+}e^{-}$ pair emission, or neutrino splitting) upon superluminal neutrino velocities. We argue that the plausible violations of energy-momentum conservation during decay may be responsible for the stable propagation of these neutrinos, and hence for the evasion of relevant constraints.

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C. Li and B. Ma
Thu, 3 Nov 22
13/59

Comments: 5 latex pages, final version for journal publication

Measuring the polarization content of gravitational waves with strongly lensed binary black hole mergers [CL]

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http://arxiv.org/abs/2211.01272


Alternative theories of gravity predict up to six distinct polarization modes for gravitational waves. Strong gravitational lensing of gravitational waves allows us to probe the polarization content of these signals by effectively increasing the number of observations from the same astrophysical source. The lensing time delays due to the multiple observed lensed images combined with the rotation of the Earth allows for effective non-collocated interferometers to be defined with respect to the source location and hence probe the alternative polarization amplitudes with more observations. To measure these amplitudes, we jointly fit the image observations to a single gravitational wave signal model that takes into account the image magnifications, time delays, and polarization mode amplitudes. We show that for certain systems, we can make a measurement of the relative mode amplitudes for lensed events with two detectable images.

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I. Hernandez
Thu, 3 Nov 22
31/59

Comments: 8 pages, 6 figures

Regular black holes sourced by nonlinear electrodynamics [CL]

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http://arxiv.org/abs/2211.00743


The paper is a brief review on the existence and basic properties of static, spherically symmetric regular black hole solutions of general relativity, where the source of gravity is represented by nonlinear electromagnetic fields with the Lagrangian function $L$ depending on the single invariant $f = F_{\mu\nu}F^{\mu\nu}$ or on two variables: either $L(f, h)$, where $h = {^}F_{\mu\nu} F^{\mu\nu}$, where ${^}F_{\mu\nu}$ is the Hodge dual of $F_{\mu\nu}$, or $L(f, J)$, where $J = F_{\mu\nu}F^{\nu\rho} F_{\rho\sigma} F^{\sigma\mu}$. A number of no-go theorems are discussed, revealing the conditions under which the space-time cannot have a regular center, among which the theorems concerning $L(f,J)$ theories are probably new. These results concern both regular black holes and regular particlelike or starlike objects (solitons) without horizons. Thus, a regular center in solutions with an electric charge $q_e\ne 0$ is only possible with nonlinear electrodynamics (NED) having no Maxwell weak field limit. Regular solutions with $L(f)$ and $L(f, J)$ NED, possessing a correct (Maxwell) weak-field limit, are possible if the system contains only a magnetic charge $q_m \ne 0$. It is shown, however, that in such solutions the causality and unitarity as well as dynamic stability conditions are inevitably violated in a neighborhood of the center. Some particular examples are discussed.

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K. Bronnikov
Thu, 3 Nov 22
36/59

Comments: 30 pages, 4 figures. Invited chapter for the edited book “Regular Black Holes: Towards a New Paradigm of the Gravitational Collapse” (Ed. C. Bambi, Springer Singapore, expected in 2023)

Primordial non-Gaussianity from Galilean Genesis without strong coupling problem [CL]

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http://arxiv.org/abs/2211.00388


Galilean Genesis is generically plagued with a strong coupling problem, but this can be avoided depending on the hierarchy between a classical energy scale of genesis and a strong coupling scale. In this paper, we investigate whether or not the models of Galilean Genesis without the strong coupling problem can explain the statistical properties of the observed CMB fluctuations based on two unified frameworks of Galilean Genesis. By focusing on the class in which the propagation speeds of the scalar and tensor perturbations are constant, we show that the models avoiding strong coupling and allowing a slightly red-tilted scalar power spectrum suffer from an overproduction of a scalar non-Gaussianity.

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S. Akama and S. Hirano
Wed, 2 Nov 22
7/67

Comments: 16 pages, 1 figure

The Bardeen-Petterson effect, disk breaking, and the spin orientations of supermassive black-hole binaries [HEAP]

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http://arxiv.org/abs/2211.00044


Supermassive black-hole binaries are driven to merger by dynamical friction, loss-cone scattering of individual stars, disk migration, and gravitational-wave emission. Two main formation scenarios are expected. Binaries that form in gas-poor galactic environments do not experience disk migration and likely enter the gravitational-wave dominated phase with roughly isotropic spin orientations. Comparatively, binaries that evolve in gas-rich galactic environments might experience prominent phases of disk accretion, where the Bardeen-Petterson effect acts to align the spins of the black holes with the orbital angular momentum of the disk. However, if the accretion disk breaks alignment is expected to be strongly suppressed — a phenomenon that was recently shown to occur in a large portion of the parameter space. In this paper, we develop a semi-analytic model of joint gas-driven migration and spin alignment of supermassive black-hole binaries taking into account the impact of disk breaking for the first time. Our model predicts the occurrence of distinct subpopulations of binaries, implying that future gravitational-wave observations of merging black holes could potentially be used to (i) discriminate between gas-rich and gas-poor hosts and (ii) constrain the dynamics of warped accretion disks.

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N. Steinle and D. Gerosa
Wed, 2 Nov 22
8/67

Comments: N/A

Global high-order numerical schemes for the time evolution of the general relativistic radiation magneto-hydrodynamics equations [CL]

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http://arxiv.org/abs/2211.00027


Modeling correctly the transport of neutrinos is crucial in some astrophysical scenarios such as core-collapse supernovae and binary neutron star mergers. In this paper, we focus on the truncated-moment formalism, considering only the first two moments (M1 scheme) within the grey approximation, which reduces Boltzmann seven-dimensional equation to a system of $3+1$ equations closely resembling the hydrodynamic ones. Solving the M1 scheme is still mathematically challenging, since it is necessary to model the radiation-matter interaction in regimes where the evolution equations become stiff and behave as an advection-diffusion problem. Here, we present different global, high-order time integration schemes based on Implicit-Explicit Runge-Kutta (IMEX) methods designed to overcome the time-step restriction caused by such behavior while allowing us to use the explicit RK commonly employed for the MHD and Einstein equations. Finally, we analyze their performance in several numerical tests.

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M. Izquierdo, L. Pareschi, B. Miñano, et. al.
Wed, 2 Nov 22
11/67

Comments: 22 pages, 11 figures

Bayesian analysis of neutron-star properties with parameterized equations of state: the role of the likelihood functions [CL]

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http://arxiv.org/abs/2211.00018


We have investigated the systematic differences introduced when performing a Bayesian-inference analysis of the equation of state of neutron stars employing either variable- or constant-likelihood functions. The former have the advantage that it retains the full information on the distributions of the measurements, making an exhaustive usage of the data. The latter, on the other hand, have the advantage of a much simpler implementation and reduced computational costs. In both approaches, the EOSs have identical priors and have been built using the sound-speed parameterization method so as to satisfy the constraints from X-ray and gravitational-waves observations, as well as those from Chiral Effective Theory and perturbative QCD. In all cases, the two approaches lead to very similar results and the $90\%$-confidence levels are essentially overlapping. Some differences do appear, but in regions where the probability density is extremely small and are mostly due to the sharp cutoff set on the binary tidal deformability $\tilde \Lambda \leq 720$ employed in the constant-likelihood analysis. Our analysis has also produced two additional results. First, a clear inverse correlation between the normalized central number density of a maximally massive star, $n_{\rm c, TOV}/n_s$, and the radius of a maximally massive star, $R_{\rm TOV}$. Second, and most importantly, it has confirmed the relation between the chirp mass $\mathcal{M}{\rm chirp}$ and the binary tidal deformability $\tilde{\Lambda}$. The importance of this result is that it relates a quantity that is measured very accurately, $\mathcal{M}{\rm chirp}$, with a quantity that contains important information on the micro-physics, $\tilde{\Lambda}$. Hence, once $\mathcal{M}_{\rm chirp}$ is measured in future detections, our relation has the potential of setting tight constraints on $\tilde{\Lambda}$.

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J. Jiang, C. Ecker and L. Rezzolla
Wed, 2 Nov 22
26/67

Comments: 16 pages, 6 figures, 2 tables

Cosmic Acceleration with and without Limits [CL]

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http://arxiv.org/abs/2211.00542


A novel, interesting class of scalar-tensor gravity theories is those with a limit on the field motion, where the scalar field either goes to a constant acceleration or stops accelerating and goes to a constant velocity. We combine these with the ability to dynamically cancel a high energy cosmological constant, e.g. through the well tempered or self tuning approaches. One can successfully have a cosmic expansion history with a matter dominated epoch and late time acceleration despite a large cosmological constant, although the late time de Sitter limit may be unstable. Pole models, such as in a Dirac-Born-Infeld action, are of particular interest for a cosmic speed limit.

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E. Linder
Wed, 2 Nov 22
45/67

Comments: 8 pages

Dimensionally Reduced Waveforms for Spin-Induced Quadrupole Searches [CL]

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http://arxiv.org/abs/2211.00039


We present highly accurate, dimensionally-reduced gravitational waveforms for binary inspirals whose components have large spin-induced quadrupole moments. The spin-induced quadrupole of a body first appears in the phase of a waveform at the early inspiral stage of the binary coalescence, making it a relatively clean probe of the internal structure of the body. However, for objects with large quadrupolar deviations from Kerr, searches using binary black hole (BBH) models would be ineffective. In order to perform a computationally-feasible search, we present two dimensionally-reduced models which are derived from the original six-dimensional post-Newtonian waveform for such systems. Our dimensional reduction method is guided by power counting in the post-Newtonian expansion, suitable reparameterizations of the source physics, and truncating terms in the phase that are small in most physically well-motivated regions of parameter space. In addition, we note that large quadrupolar deviations cause the frequency at which a binary system reaches its minimum binding energy to be reduced substantially. This minimum signals the end of the inspiral regime and provides a natural cutoff for the PN waveform. We provide accurate analytic estimates for these frequency cutoffs. Finally, we perform injection studies to test the effectualness of the dimensionally reduced waveforms. We find that over $80\%$ of the injections have an effectualness of $\varepsilon > 0.999$, significantly higher than is typically required for standard BBH banks, for systems with component spins of $|\chi_i| \lesssim 0.6$ and dimensionless quadrupole of $\kappa_i \lesssim 10^3$. Importantly, these waveforms represent an essential first step towards enabling an effective search for astrophysical objects with large quadrupoles.

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H. Chia, T. Edwards, R. George, et. al.
Wed, 2 Nov 22
50/67

Comments: 18 pages, 10 figures

Dark Energy as a Post-Inflation Effect in Quadratic Gravity [CL]

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http://arxiv.org/abs/2211.00491


We analytically and numerically show that the acceleration of the cosmic expansion could be explained by a Quadratic Gravity model which is known to be able to trigger sufficient inflation, with neither negative pressure matter nor cosmological constant. Accordingly, it suggests that the Dark Energy could possibly be a post-inflation effect in Quadratic Gravity. We also show that this model admits all Einstein metrics as its solutions. Consequently, classic tests of Einstein’s Gravity cannot falsify this model.

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H. Chang
Wed, 2 Nov 22
51/67

Comments: 16 pages, 3 figures

Ultra-high energy cosmic neutrinos from gamma-ray bursts [HEAP]

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http://arxiv.org/abs/2211.00231


Ultra-high energy cosmic neutrinos from gamma-ray burstsBased on recent proposal to associate IceCube TeV and PeV neutrino events with gamma-ray bursts~(GRBs) by considering the Lorentz violation of neutrinos, we provide a new estimate on the GRB neutrino flux and such result is much bigger than previous results by the IceCube Collaboration. Among these 24 neutrino “shower” events above 60~TeV, 12 events are associated with GRBs. Such result is comparable with the prediction from GRB fireball models. Analysis of track events provide consistent result with the shower events to associate high energy cosmic neutrinos with GRBs under the same Lorentz violation features of neutrinos. We also make a background estimation and reveal GRBs as a significant source for the ultra-high energy IceCube neutrino events. Our work supports the Lorentz violation and $CPT$-violation of neutrinos, indicating new physics beyond relativity.

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Y. Huang and B. Ma
Wed, 2 Nov 22
55/67

Comments: 8 latex pages, 3 figures, final version for journal publication

Shadow of black hole surrounded by magnetized plasma: Axion-plasmon cloud [CL]

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http://arxiv.org/abs/2211.00300


By exploiting the extreme environment of the black hole (BH) as a potential place for axion-photon interaction, we use an axion-producing model of the magnetized plasma to study the shadow of an asymptotically flat rotating BH immersed into an axion-plasmon cloud. By aiming to reveal footprints of axion in the dark shadow of BH, we in this paper explore the influence of the fixed axion-plasmon background on the motion of incident photons around the rotating BH. Under some free parameter settings, we find that axion-plasmon cloud around rotating BH affects the shape and size of the shadow in such a way that its role is distinguishable from non-magnetized plasma and standard vacuum solutions. By being limited to high rotation BH, we show that the size of the BH shadow increases as the axion-plasmon coupling gets strong. Interestingly, our analysis indicates that as the mass of axion gets heavier, it can leave a subtle imprint of itself on the shadow. Conversely, in the non-rotating limit (Schwarzschild), by recovering the spherical symmetry of the shadow shape of BH, its size decreases. In coordination with the trend of change in shadow size, the investigation of the energy emission from the BH surrounded by the magnetized plasma shows that the maximal energy emission rate from the rotating BH in the presence of axion-plasmon cloud increases compared to the non-magnetized plasma and the vacuum solutions. Subsequently, by relaxing the rotation, the axion-plasmon cloud causes a decrease in the energy emission rate from the BH.

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M. Khodadi
Wed, 2 Nov 22
58/67

Comments: 23 pages, 15 figures, for publication in ” Nuclear Physics B”

Primordial Black Hole Mass Function with Mass Gap [CEA]

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http://arxiv.org/abs/2210.16479


In this paper, we investigate the primordial black hole (PBH) mass function with mass gap. Firstly, to obtain a data-supported PBH mass function with mass gap for subsolar masses PBHs, we fine-tune the coefficients of a model-independent power spectrum of primordial curvature perturbations. Then we take this unique PBH mass function into consideration and calculate the energy density spectrum of the stochastic gravitational wave background from PBH mergers. We find the location of its first peak almost has no relationship with the mass gap and is only determined by the probability distribution of frequencies at which PBH binaries merge. Apart from the first peak, there must be an accompanying smaller trough at higher frequency resulting from the mass gap. Therefore, the detection of this smaller trough will provide more information about inflation and PBH formation.

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X. Bi, L. Chen and K. Wang
Tue, 1 Nov 22
1/100

Comments: 8 pages, 4 figures

An instrumented baffle for the Advanced Virgo Input Mode Cleaner End Mirror [CL]

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http://arxiv.org/abs/2210.16313


A novel instrumented baffle surrounding the suspended end mirror in the input mode cleaner cavity of the Virgo interferometer was installed in spring 2021. Since then, the device has been regularly operated in the experiment and the obtained results indicate a good agreement with simulations of the stray light inside the optical cavity. The baffle will operate in the upcoming O4 observation run, serving as a demonstrator of the technology designed to instrument the baffles in front of the main mirrors in time for O5. In this paper we present a detailed description of the baffle design, including mechanics, front-end electronics, data acquisition, as well as optical and vacuum tests, calibration and installation procedures, and performance results.

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M. Andres-Carcasona, O. Ballester, O. Blanch, et. al.
Tue, 1 Nov 22
11/100

Comments: 12 pages, 21 figures, 3 tables, to be submitted to PRD

Formalizing Anisotropic Inflation in Modified Gravity [CL]

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http://arxiv.org/abs/2210.16383


Motivated by the fact that the pre-inflationary era may evolve in an exotic way, in this work we formalize anisotropic evolution in the context of modified gravity, focusing on pre-inflationary and near the vicinity of the inflationary epochs. We specialize on specific metrics like Bianchi and Taub and we formalize the inflationary theory in vacuum $F(R)$ gravity, in $F(R)$ gravity with an extra scalar field and in Gauss-Bonnet gravity. We discuss the qualitative effects of the anisotropies on the evolution of the Universe and also we consider several specific solutions, like the de Sitter solution, in both the isotropic and anisotropic contexts. Furthermore, several exotic modified gravity cosmological solutions, like the ones which contain finite time singularities, are also discussed in brief.

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S. Nojiri, S. Odintsov, V. Oikonomou, et. al.
Tue, 1 Nov 22
17/100

Comments: NPB Accepted

Second release of the CoRe database of binary neutron star merger waveforms [CL]

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http://arxiv.org/abs/2210.16366


We present the second data release of gravitational waveforms from binary neutron star merger simulations performed by the Computational Relativity (CoRe) collaboration. The current database consists of 254 different binary neutron star configurations and a total of 590 individual numerical-relativity simulations using various grid resolutions. The released waveform data contain the strain and the Weyl curvature multipoles up to $\ell=m=4$. They span a significant portion of the mass, mass-ratio,spin and eccentricity parameter space and include targeted configurations to the events GW170817 and GW190425. CoRe simulations are performed with 18 different equations of state, seven of which are finite temperature models, and three of which account for non-hadronic degrees of freedom. About half of the released data are computed with high-order hydrodynamics schemes for tens of orbits to merger; the other half is computed with advanced microphysics. We showcase a standard waveform error analysis and discuss the accuracy of the database in terms of faithfulness. We present ready-to-use fitting formulas for equation of state-insensitive relations at merger (e.g. merger frequency), luminosity peak, and post-merger spectrum.

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A. Gonzalez, F. Zappa, M. Breschi, et. al.
Tue, 1 Nov 22
18/100

Comments: 33 pages, 14 figures

Cosmology in theories with spontaneous scalarization of neutron stars [CL]

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http://arxiv.org/abs/2210.16983


In a model of spontaneous scalarization of neutron stars proposed by Damour and Esposite-Farese, a general relativistic branch becomes unstable to trigger tachyonic growth of a scalar field $\phi$ toward a scalarized branch. Applying this scenario to cosmology, there is fatal tachyonic instability of $\phi$ during inflation and matter dominance being incompatible with solar-system constraints on today’s field value $\phi_0$. In the presence of a four-point coupling $g^2 \phi^2 \chi^2/2$ between $\phi$ and an inflaton field $\chi$, it was argued by Anson et al. that a positive mass squared heavier than the square of a Hubble expansion rate leads to the exponential suppression of $\phi$ during inflation and that $\phi_0$ can remain small even with the growth of $\phi$ after the radiation-dominated epoch. For several inflaton potentials approximated as $V(\chi)=m^2 \chi^2/2$ about the potential minimum, we study the dynamics of $\phi$ during reheating as well as other cosmological epochs in detail. For certain ranges of the coupling $g$, the homogeneous field $\phi$ can be amplified by parametric resonance during a coherent oscillation of the inflaton. Incorporating the backreaction of created particles under a Hartree approximation, the maximum values of $\phi$ reached during preheating are significantly smaller than those obtained without the backreaction. We also find that the minimum values of $g$ consistent with solar system bounds on $\phi$ at the end of reheating are of order $10^{-5}$ and hence there is a wide range of acceptable values of $g$. Thus, the scenario proposed by Anson et al. naturally leads to the viable cosmological evolution of $\phi$ consistent with local gravity constraints, without modifying the property of scalarized neutron stars.

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R. Nakarachinda, S. Panpanich, S. Tsujikawa, et. al.
Tue, 1 Nov 22
20/100

Comments: 15 pages, 8 figures

Thick branes via higher order field theory models with exponential and power-law tails [CL]

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http://arxiv.org/abs/2210.17387


In this work, we obtain exact thick brane models in $4+1$ dimensions generated by higher order field theory kinks, inspired by specific potentials for $\phi^{10}$ and $\phi^{18}$ models. We verify that the geodesic equation along the fifth dimension confirms the confining effects of the scalar field on the brane for all of these models. These models provide new solutions with exponential and power-law tails which live in different topological sectors. We show that the resulting branes of specific exponential law models do not possess $Z_2$-symmetry. Furthermore, we examine the stability of the thick branes, by determining the sign of the $w^2$ term in the expansion of the potential for the resulting Schr\”{o}dinger-like equation. It turns out that two of the three models of the $\phi^{10}$ brane are stable, while another contains unstable modes for certain ranges of the model parameters. We also show that the brane solution from the specific $\phi^{18}$ models are stable, while the others involve neutral equilibrium. The asymptotic behaviour of the brane solutions are also discussed.

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M. Peyravi, S. Nazifkar, F. Lobo, et. al.
Tue, 1 Nov 22
27/100

Comments: 23 pages, 10 figures. arXiv admin note: text overlap with arXiv:1504.04603

Direct tests of General Relativity under screening effect with galaxy-scale strong lensing systems [CEA]

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http://arxiv.org/abs/2210.16752


Observations of galaxy-scale strong gravitational lensing (SGL) systems have enabled unique tests of nonlinear departures from general relativity (GR) on the galactic and supergalactic scales. One of the most important cases of such tests is constraints on the gravitational slip between two scalar gravitational potentials. In this paper, we use a newly compiled sample of strong gravitational lenses to test the validity of GR, focusing on the screening effects on the apparent positions of lensed sources relative to the GR predictions. This is the first simultaneous measurement of the Post-Newtonian (PN) parameter ($\gamma_{PN}$) and the screening radius ($\Lambda$) without any assumptions about the contents of the Universe. Our results suggest that the measured PPN is marginally consistent with GR ($\gamma_{PN}=1$) with increasing screening radius ($\Lambda = 10-300 $kpc), although the choice of lens models may have a significant influence on the final measurements. Based on a well-defined sample of 5000 simulated strong lenses from the forthcoming LSST, our methodology will provide a strong extragalactic test of GR with an accuracy of 0.5\%, assessed up to scales of $\Lambda \sim 300$ kpc. For the current and future observations of available SGL systems, there is no noticeable evidence indicating some specific cutoff scales on kpc-Mpc scales, beyond which new gravitational degrees of freedom are expressed.

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Y. Lian, S. Cao, T. Liu, et. al.
Tue, 1 Nov 22
29/100

Comments: 14 pages, 9 figures, accepted for publication in ApJ

Missing one-loop contributions in secondary gravitational waves [CEA]

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http://arxiv.org/abs/2210.17176


We find several missing one-loop-order contributions in previous considerations about secondary gravitational waves induced at nonlinear order in cosmological perturbations. We consider a consistent perturbative expansion to third-order in cosmological perturbations, including higher-order interactions and iterative solutions ignored in the previous literature. Tensor fluctuations induced by the source with two scalar and one tensor perturbations are correlated with the first-order tensor fluctuation and thus give a one-loop-order correction to the tensor power spectrum. The missing loop correction is \textit{scale-invariant} and \textit{negative} in the superhorion region, which secondarily reduces the initial primordial tensor power spectrum prior to the horizon re-entry. Such an IR behavior is very different from the auto-spectrum of second-order induced tensor modes discussed in the previous literature and can be important for the actual gravitational wave measurements. For a sharp peak of scalar fluctuations with $A_\zeta=10^{-2}$ at $k_*=10^{5}h/{\rm Mpc}$ motivated by the LIGO/Virgo events, we show that the tensor power spectrum at the cosmic microwave background scale reduces by at most 35%. Hence, the polarization B-mode might not be seen because of the reduction of the original tensor spectrum due to the secondary effect of primordial black hole formation.

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C. Chen, A. Ota, H. Zhu, et. al.
Tue, 1 Nov 22
31/100

Comments: 13 pages, 6 figures

Colliding Ghosts: Constraining Inflation with the Parity-Odd Galaxy Four-Point Function [CEA]

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http://arxiv.org/abs/2210.16320


Could new physics break the mirror symmetry of the Universe? Utilizing recent measurements of the parity-odd four-point correlation function of BOSS galaxies, we probe the physics of inflation by placing constraints on the amplitude of a number of parity-violating models. Within canonical models of (single-field, slow-roll) inflation, no parity-asymmetry can occur; however, it has recently been shown that breaking of the standard assumptions can lead to parity violation within the Effective Field Theory of Inflation (EFTI). In particular, we consider the Ghost Condensate and Cosmological Collider scenarios – the former for the leading and subleading operators in the EFTI and the latter for different values of mass and speed of an exchanged spin-$1$ particle – for a total of $18$ models. Each instance yields a definite prediction for the inflationary trispectrum, which we convert to a late-time galaxy correlator prediction (through a highly non-trivial calculation) and constrain using the observed data. We find no evidence for inflationary parity-violation (with each of the $18$ models having significances below $2.4\sigma$), and place the first constraints on the relevant coupling strengths, at a level comparable with the theoretical perturbativity bounds. This is also the first time Cosmological Collider signatures have directly been searched for in observational data. We further show that possible secondary parity-violating signatures in galaxy clustering can be systematically described within the Effective Field Theory of Large-Scale Structure. We argue that these late-time contributions are subdominant compared to the primordial parity-odd signal for a vast region of parameter space. In summary, the results of this paper disfavor the notion that the recent hints of parity-violation observed in the distribution of galaxies are due to new physics.

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G. Cabass, M. Ivanov and O. Philcox
Tue, 1 Nov 22
40/100

Comments: 20+8 spooky pages, 4 figures, submitted to Phys. Rev. D. Code available at this https URL

Numerical stochastic inflation constrained by frozen noise [CEA]

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http://arxiv.org/abs/2210.17441


Stochastic inflation can resolve strong inflationary perturbations, which seed primordial black holes. I present a fast and accurate way to compute these perturbations in typical black hole producing single-field models, treating the short-wavelength Fourier modes beyond the de Sitter approximation. The squeezing and freezing of the modes reduces the problem to one dimension, and the resulting new form of the stochastic equations, dubbed `constrained stochastic inflation’, can be solved efficiently with semi-analytical techniques and numerical importance sampling. In an example case, the perturbation distribution is resolved in seconds deep into its non-Gaussian tail, a speed-up of factor $10^9$ compared to a previous study. Along the way, I comment on the role of the momentum constraint in stochastic inflation.

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E. Tomberg
Tue, 1 Nov 22
46/100

Comments: 34 pages, 8 figures

GRaM-X: A new GPU-accelerated dynamical spacetime GRMHD code for Exascale computing with the Einstein Toolkit [IMA]

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http://arxiv.org/abs/2210.17509


We present GRaM-X (General Relativistic accelerated Magnetohydrodynamics on AMReX), a new GPU-accelerated dynamical-spacetime general relativistic magnetohydrodynamics (GRMHD) code which extends the GRMHD capability of Einstein Toolkit to GPU-based exascale systems. GRaM-X supports 3D adaptive mesh refinement (AMR) on GPUs via a new AMR driver for the Einstein Toolkit called CarpetX which in turn leverages AMReX, an AMR library developed for use by the United States DOE’s Exascale Computing Project (ECP). We use the Z4c formalism to evolve the equations of GR and the Valencia formulation to evolve the equations of GRMHD. GRaM-X supports both analytic as well as tabulated equations of state. We implement TVD and WENO reconstruction methods as well as the HLLE Riemann solver. We test the accuracy of the code using a range of tests on static spacetime, e.g. 1D MHD shocktubes, the 2D magnetic rotor and a cylindrical explosion, as well as on dynamical spacetimes, i.e. the oscillations of a 3D TOV star. We find excellent agreement with analytic results and results of other codes reported in literature. We also perform scaling tests and find that GRaM-X shows a weak scaling efficiency of $\sim 40-50\%$ on 2304 nodes (13824 NVIDIA V100 GPUs) with respect to single-node performance on OLCF’s supercomputer Summit.

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S. Shankar, P. Mösta, S. Brandt, et. al.
Tue, 1 Nov 22
69/100

Comments: 22 pages, 8 figures, to be submitted to Classical and Quantum Gravity

Simulations of light distribution on new instrumented baffles surrounding Virgo end mirrors [CL]

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http://arxiv.org/abs/2210.16308


As part of the second phase of Advanced Virgo upgrade program, instrumented baffles are being constructed to be installed around the end mirrors in the main arms, in continuation of what has been implemented for the input mode cleaner end mirror during phase I. These baffles will be equipped with photosensors, allowing for real-time monitoring of the stray light around the mirrors. In this paper, we present optical simulations of the light distribution in the detector main cavities to assess the ability of the sensors to effectively monitor misalignment and defects on the mirrors surface and to play a role in the pre-alignment of the interferometer.

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A. Macquet, M. M.Andrés-Carcasona, M. Martinez, et. al.
Tue, 1 Nov 22
77/100

Comments: N/A

Non-Gaussianities in generalized non-local $R^2$-like inflation [CL]

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http://arxiv.org/abs/2210.16459


In [1], a most general higher curvature non-local gravity action admitting $R^2$-like inflationary solution predicting scalar spectral index $n_s(N)\approx 1-\frac{2}{N}$, where $N$ is the number of e-folds before the end of inflation, $N\gg 1$, any value of the tensor-to-scalar ratio $r(N)<0.036$ and tensor tilt $n_t(N)$ violating the $r= -8n_t$ condition was obtained. In this paper, we compute scalar primordial non-Gaussianities (PNGs) in this theory and effectively demonstrate that higher curvature non-local terms lead to new shapes of reduced bispectrum $f_{\rm NL}\left( k_1,\,k_2,\,k_3 \right)$ mimicking several classes of scalar field models of inflation known in the literature. We obtain $\vert f_{\rm NL}\vert \sim O(1-10)$ in the equilateral, orthogonal, and squeezed limits and the running of PNGs measured by the quantity $\vert\frac{d\ln f_{\rm NL}}{d\ln k}\vert\lesssim 1$. We project these results in the scope of future CMB, Large Scale Structure observations to probe the nature of quantum gravity. Furthermore, we demonstrate that $R^2$-like inflation in non-local modification of gravity brings a paradigm shift in our understanding of early Universe cosmology through non-trivial predictions which go beyond the current status of effective field theories (EFTs) of single field, quasi-single field, and multiple field inflation. In summary, through our generalized non-local $R^2$-like inflation, we obtain for the first time a robust geometric framework of inflation that can explain any detection of observable quantities related to scalar PNGs.

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A. Koshelev, K. Kumar and A. Starobinsky
Tue, 1 Nov 22
80/100

Comments: 30 pages, 7 figures

Gravitational Larmor precession [CL]

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http://arxiv.org/abs/2210.17162


We model the reported existence of substantive magnetic fields in the vicinity of the central supermassive black holes in Sagitarius A* and Messier 87*, in terms of an axisymmetric, non-rotating Ernst-Melvin-Schwarzschild black hole spacetime with appropriate parameters. We compute the geodesic nodal-plane precession frequency for a test particle with mass, for such a spacetime, and obtain a non-vanishing result, surpassing earlier folklore that only axisymmetric spacetimes with rotation (non-vanishing Kerr parameter) can generate such a precession. We call this magnetic field-generated phenomenon Gravitational Larmor Precession. We discuss observational prospects of this precession in terms of available magnetic field strengths close to central black holes in galaxies.

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C. Chakraborty and P. Majumdar
Tue, 1 Nov 22
89/100

Comments: 7 pages including 2 figures

The estimation of far-field wavefront error of tilt-to-length distortion coupling in space-based gravitational wave detection [IMA]

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http://arxiv.org/abs/2210.16317


In space-based gravitational wave detection, the estimation of far-field wavefront error of the distorted beam is the precondition for the noise reduction. Zernike polynomials is used to describe the wavefront error of the transmitted distorted beam. The propagation of a laser beam between two telescope apertures is calculated numerically. Far-field wavefront error is estimated with the absolute height of the peak-to-valley phase deviation between distorted Gaussian beam and a reference distortion-free Gaussian beam. The results show the pointing jitter is strongly related to the wavefront error. Furthermore, when jitter decreases 10 times from 100 to 10 nrad, wavefront error reduces for more than an order of magnitude. In the analysis of multi-parameter minimization, the minimum of wavefront error tends to Z[5,3] Zernike in some parameter ranges. Some Zernikes have a strong correlation with wavefront error of the received beam. When the aperture diameter increases at Z[5,3] Zernike, wavefront error is not monotonic and has oscillation. Nevertheless, wavefront error almost remains constant with the arm length increasing from 10$^{-1}$ Mkm to 10$^3$ Mkm. When the arm length decreases for three orders of magnitude from 10$^{-1}$ Mkm to 10$^{-4}$ Mkm, wavefront error has only an order of magnitude increasing. In the range of 10$^{-4}$ Mkm to 10$^3$ Mkm, the lowest limit of the wavefront error is from 0.5 fm to 0.015 fm, at Z[5,3] Zernike and 10 nrad jitter.

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Y. Tao, H. Jin and Y. Wu
Tue, 1 Nov 22
94/100

Comments: 13 pages, 7 figures

Soft theorems for boosts and other time symmetries [CL]

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http://arxiv.org/abs/2210.16276


We derive soft theorems for theories in which time symmetries — symmetries that involve the transformation of time, an example of which are Lorentz boosts — are spontaneously broken. The soft theorems involve unequal-time correlation functions with the insertion of a soft Goldstone in the far past. Explicit checks are provided for several examples, including the effective theory of a relativistic superfluid and the effective field theory of inflation. We discuss how in certain cases these unequal-time identities capture information at the level of observables that cannot be seen purely in terms of equal-time correlators of the field alone. We also discuss when it is possible to phrase these soft theorems as identities involving equal-time correlators.

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L. Hui, A. Joyce, I. Komissarov, et. al.
Mon, 31 Oct 22
4/60

Comments: 50 pages

Deep Learning Detection and Classification of Gravitational Waves from Neutron Star-Black Hole Mergers [IMA]

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http://arxiv.org/abs/2210.15888


The Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo Interferometer Collaborations have now detected all three classes of compact binary mergers: binary black hole (BBH), binary neutron star (BNS), and neutron star-black hole (NSBH). For coalescences involving neutron stars, the simultaneous observation of gravitational and electromagnetic radiation produced by an event, has broader potential to enhance our understanding of these events, and also to probe the equation of state (EOS) of dense matter. However, electromagnetic follow-up to gravitational wave (GW) events requires rapid real-time detection and classification of GW signals, and conventional detection approaches are computationally prohibitive for the anticipated rate of detection of next-generation GW detectors. In this work, we present the first deep learning based results of classification of GW signals from NSBH mergers in \textit{real} LIGO data. We show for the first time that a deep neural network can successfully distinguish all three classes of compact binary mergers and separate them from detector noise. Specifically, we train a convolutional neural network (CNN) on $\sim 500,000$ data samples of real LIGO noise with injected BBH, BNS, and NSBH GW signals, and we show that our network has high sensitivity and accuracy. Most importantly, we successfully recover the two confirmed NSBH events to-date (GW200105 and GW200115) and the two confirmed BNS mergers to-date (GW170817 and GW190425), together with $\approx 90\%$ of all BBH candidate events from the third Gravitational Wave Transient Catalog, GWTC-3. These results are an important step towards low-latency real-time GW detection, enabling multi-messenger astronomy.

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R. Qiu, P. Krastev, K. Gill, et. al.
Mon, 31 Oct 22
6/60

Comments: 8 pages, 5 figures. arXiv admin note: text overlap with arXiv:2012.13101

Outlook for detecting the gravitational wave displacement and spin memory effects with current and future gravitational wave detectors [CL]

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http://arxiv.org/abs/2210.16266


Gravitational wave memory effects arise from non-oscillatory components of gravitational wave signals, and they are predictions of general relativity in the nonlinear regime that have close connections to the asymptotic properties of isolated gravitating systems. There are many types of memory effects that have been studied in the literature. In this paper we focus on the “displacement” and “spin” memories, which are expected to be the largest of these effects from sources such as the binary black hole mergers which have already been detected by LIGO and Virgo. The displacement memory is a change in the relative separation of two initially comoving observers due to a burst of gravitational waves, whereas the spin memory is a portion of the change in relative separation of observers with initial relative velocity. As both of these effects are small, LIGO, Virgo, and KAGRA can only detect memory effects from individual events that are much louder (and thus rarer) than those that have been detected so far. By combining data from multiple events, however, these effects could be detected in a population of binary mergers. In this paper, we present new forecasts for how long current and future detectors will need to operate in order to measure these effects from populations of binary black hole systems that are consistent with the populations inferred from the detections from LIGO and Virgo’s first three observing runs. We find that a second-generation detector network of LIGO, Virgo, and KAGRA operating at the O4 (“design”) sensitivity for 1.5 years and then operating at the O5 (“plus”) sensitivity for an additional year can detect the displacement memory. For Cosmic Explorer, we find that displacement memory could be detected for individual loud events, and that the spin memory could be detected in a population after 5 years of observation time.

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A. Grant and D. Nichols
Mon, 31 Oct 22
10/60

Comments: 17+7 pages, 7 figures

Torsion fields generated by the quantum effects of macro-bodies [CL]

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http://arxiv.org/abs/2210.16245


We generalize Einstein’s General Relativity (GR) by assuming that all matter (including macro-objects) has quantum effects. An appropriate theory to fulfill this task is Gauge Theory Gravity (GTG) developed by the Cambridge group. GTG is a “spin-torsion” theory, according to which, gravitational effects are described by a pair of gauge fields defined over a flat Minkowski background spacetime. The matter content is completely described by the Dirac spinor field, and the quantum effects of matter are identified as the spin tensor derived from the spinor field. The existence of the spin of matter results in the torsion field defined over spacetime. Torsion field plays the role of Bohmian quantum potential which turns out to be a kind of repulsive force as opposed to the gravitational potential which is attractive. The equivalence principle remains and essential in this theory so that GR is relegated to a locally approximate theory wherein the quantum effects (torsion) are negligible. As a toy model, we assume that the macro matter content can be described by the covariant Dirac equation and apply this theory to the simplest radially symmetric and static gravitational systems. Consequently, by virtue of the cosmological principle, we are led to a static universe model in which the Hubble redshifts arise from the torsion fields.

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D. Chen
Mon, 31 Oct 22
13/60

Comments: 21 pages, accepted for publication in Research in Astronomy and Astrophysics

Constraining properties of asymmetric dark matter candidates from gravitational-wave observations [CL]

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http://arxiv.org/abs/2210.15739


The accumulation of certain types of dark matter particles in neutron star cores due to accretion over long timescales can lead to the formation of a mini black hole. In this scenario, the neutron star is destabilized and implodes to form a black hole without significantly increasing its mass. When this process occurs in neutron stars in coalescing binaries, one or both stars might be converted to a black hole before they merge. Thus, in the mass range of $\sim \mbox{1–2}\, M_\odot,$ the Universe might contain three distinct populations of compact binaries: one containing only neutron stars, the second population of only black holes, and a third, mixed population consisting of a neutron star and a black hole. However, it is unlikely to have a mixed population as the various timescales allow for both neutron stars to remain or collapse within a short timescale. In this paper, we explore the capability of future gravitational-wave detector networks, including upgrades of Advanced LIGO and Virgo, and new facilities such as the Cosmic Explorer and Einstein Telescope (XG network), to discriminate between different populations by measuring the effective tidal deformability of the binary, which is zero for binary black holes but nonzero for binary neutron stars. Furthermore, we show that observing the relative abundances of the different populations can be used to infer the timescale for neutron stars to implode into black holes, and in turn, provide constraints on the particle nature of dark matter. The XG network will infer the implosion timescale to within an accuracy of 0.01 Gyr at 90% credible interval and determine the dark matter mass and interaction cross section to within a factor of 2 GeV and 10 cm$^{-2}$, respectively.

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D. Singh, A. Gupta, E. Berti, et. al.
Mon, 31 Oct 22
15/60

Comments: N/A

Minidisk Influence on Flow Variability in Accreting Spinning Black Hole Binaries: Simulations in Full General Relativity [HEAP]

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http://arxiv.org/abs/2210.15686


We perform magnetohydrodynamic simulations of accreting, equal-mass binary black holes in full general relativity focusing on the effect of spin and minidisks on the accretion rate and Poynting luminosity variability. We report on the structure of the minidisks and periodicities in the mass of the minidisks, mass accretion rates, and Poynting luminosity. The accretion rate exhibits a quasi-periodic behavior related to the orbital frequency of the binary in all systems that we study, but the amplitude of this modulation is dependent on the existence of persistent minidisks. In particular, systems that are found to produce persistent minidisks have a much weaker modulation of the mass accretion rate, indicating that minidisks can increase the inflow time of matter onto the black holes, and dampen out the quasi-periodic behavior. This finding has potential consequences for binaries at greater separations where minidisks can be much larger and may dampen out the periodicities significantly.

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J. Bright and V. Paschalidis
Mon, 31 Oct 22
19/60

Comments: Submitted to MNRAS. 10 pages, 10 figures

Resolving the Hubble tension with Early Dark Energy [CEA]

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http://arxiv.org/abs/2210.16296


Early dark energy (EDE) offers a solution to the so-called Hubble tension. Recently, it was shown that the constraints on EDE using Markov Chain Monte Carlo are affected by prior volume effects. The goal of this paper is to present constraints on the fraction of EDE, $f_\mathrm{EDE}$, and the Hubble parameter, $H_0$, which are not subject to prior volume effects. We conduct a frequentist profile likelihood analysis considering Planck cosmic microwave background, BOSS full-shape galaxy clustering, DES weak lensing, and SH0ES supernova data. Contrary to previous findings, we find that $H_0$ for the EDE model is in statistical agreement with the SH0ES direct measurement at $\leq 1.7\,\sigma$ for all data sets. For our baseline data set (Planck + BOSS), we obtain $f_\mathrm{EDE} = 0.087\pm 0.037$ and $H_0 = 70.57 \pm 1.36\, \mathrm{km/s/Mpc}$ at $68\%$ confidence limit. We conclude that EDE is a viable solution to the Hubble tension.

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L. Herold and E. Ferreira
Mon, 31 Oct 22
24/60

Comments: 6 pages, 3 figures, 1 table

Constrain the Merger History of Primordial-Black-Hole Binaries from GWTC-3 [CEA]

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http://arxiv.org/abs/2210.16094


Primordial black holes (PBHs) can be not only cold dark matter candidates but also progenitors of binary black holes observed by LIGO-Virgo-KAGRA (LVK) Collaboration. The PBH mass can be shifted to the heavy distribution if multi-merger processes occur. In this work, we constrain the merger history of PBH binaries using the gravitational wave events from the third Gravitational-Wave Transient Catalog (GWTC-3). Considering four commonly used PBH mass functions, namely the log-normal, power-law, broken power-law, and critical collapse forms, we find that the multi-merger processes make a subdominant contribution to the total merger rate. Therefore, the effect of merger history can be safely ignored when estimating the merger rate of PBH binaries. We also find that GWTC-3 is best fitted by the log-normal form among the four PBH mass functions and confirm that the stellar-mass PBHs cannot dominate cold dark matter.

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L. Liu, Z. You, Y. Wu, et. al.
Mon, 31 Oct 22
32/60

Comments: 10 pages, 8 figures, 2 tables

Overlap reduction functions for a polarized stochastic gravitational-wave background in the Einstein Telescope-Cosmic Explorer and the LISA-Taiji networks [CL]

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http://arxiv.org/abs/2210.16143


The detection of gravitational waves from coalescences of binary compact stars by current interferometry experiments has opened up a new era of gravitational-wave astrophysics and cosmology. The search for stochastic gravitational-wave background is underway by correlating signals from a pair of detectors in the detector network formed by the LIGO, Virgo, and KAGRA. In a previous work, we have developed a method based on spherical harmonic expansion to calculate the overlap reduction functions of the LIGO-Virgo-KAGRA network for a polarized stochastic gravitational-wave background. In this work, we will apply the method to calculate the overlap reduction functions of third-generation detectors such as a ground-based network linking the Einstein Telescope and the Cosmic Explorer, and the LISA-Taiji joint space mission.

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G. Liu and K. Ng
Mon, 31 Oct 22
33/60

Comments: 16 pages, 10 figures. arXiv admin note: text overlap with arXiv:2002.01606

Re-investigating stellar, solar and galactic spectral modulations: rapidly oscillating spacetime effects due to axions or numerical ghosts? [GA]

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http://arxiv.org/abs/2210.15983


In our previous work [Tamburini and Licata (2017)] we discussed the hypothesis that the ultrafast periodic spectral modulations with frequency $f_S \simeq 0.61$ THz found by Borra and Trottier (2016) in $236$ main sequence stars from a sample of $2.5$ million spectra of galactic halo stars of the Sloan Digital Sky Survey were due to axion-like dark matter piled up in the center of these stars. These temporary matter/dark matter structures are characterized by a spacetime geometry rapidly oscillating at frequencies that depend on the axion mass $m_a$ [Brito {\it et~al.} (2015); Brito {\it et~al.} (2016)]. Borra (2013) found two additional frequencies, $ f_{1,G} \simeq 9.5$ THz and $f_{2,G} \simeq 8.9$ THz, in the Sloan dataset of galaxies, redshifted by the cosmological expansion and, for any redshift value, $f_S + f_{2,G} = f_{1,G}$ is found. Hippke (2019) showed that $f_{2,G}$ is spurious and introduced by the data analysis procedure due to the nonrandom spacing of the spectral absorption lines. This was not even found by Isaacson (2019) when re-observed four of these stars with different instrumentation and data reduction procedure. Interestingly, Hippke found $f_S$ in the solar spectrum but not in the Kurucz (2005) artificial solar spectrum whilst its spectral power estimated by Isaacson resulted below the accepted error $(1\%)$. From these results, we discuss the validity of our ansatz by analyzing the common features present in all the spectra. In the worst case, if all the three frequencies are not real the oscillating axion core models is not valid. Assuming, instead, the validity of $f_S$ from the results from the analysis of the solar spectra, those oscillating modes may be transient modes favoring the axion hypothesis in the mass range $(10^{- 3} < m_a < 2.4 \times 10^{3})~ \mathrm{\mu eV}$, also according to the recent limits from the gamma ray burst GRB221009A.

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F. Tamburini and I. Licata
Mon, 31 Oct 22
44/60

Comments: 9 pages, 1 table