Tootfinder

Propagation and emission of gravitational waves in the weak-field limit within the Palatini formalism
Albert Duran-Cabac\'es, Diego S\'aez-Chill\'on G\'omez
https://arxiv.org/abs/2403.04683

Propagation and emission of gravitational waves in the weak-field limit within the Palatini formalism
In the era of gravitational waves physics, when detections of wave fronts are increasing in number, sensibility, frequencies and distances, gravitational physics has entered a period of maximum activity and brilliance. This has open a new window where General Relativity can be challenged in both weak as strong-field regimes. In this paper, we focus on the analysis of gravitational waves propagation and emission in the weak-field regime for gravitational theories within the Palatini formalism. O…

Tensor bispectrum mediated by an excited scalar field during inflation
Zhi-Zhang Peng, Cheng-Jun Fang, Zong-Kuan Guo
https://arxiv.org/abs/2403.04617 https…

Tensor bispectrum mediated by an excited scalar field during inflation
We calculate the tensor bispectrum mediated by an excited scalar field during inflation and find that the bispectrum peaks in the squeezed configuration, which is different from that of gravitational waves induced by enhanced curvature perturbations re-entering the horizon in the radiation-dominated era. Measuring the bispectrum provides a promising way to distinguish the stochastic gravitational-wave background generated during inflation from that generated after inflation.

This https://arxiv.org/abs/2401.08370 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_qu…

Digital quantum simulation of gravitational optomechanics with IBM quantum computers
We showcase the digital quantum simulation of the action of a Hamiltonian that governs the interaction between a quantum mechanical oscillator and an optical field, generating quantum entanglement between them via gravitational effects. This is achieved by making use of a boson-qubit mapping protocol and a digital gate decomposition that allow us to run the simulations in the quantum computers available in the IBM Quantum platform. We present the obtained results for the fidelity of the experim…

Backfiring Bosonisation
Philip Boyle Smith, Yunqin Zheng
https://arxiv.org/abs/2403.03953 https://arxiv.org/pdf/2403.03953

Backfiring Bosonisation
For a fermionic quantum field theory in $d=1+1$ dimensions, there is a subtle difference between summing over spin structures and gauging $(-1)^F$. If the gravitational anomaly vanishes mod 16, then both operations are equivalent and yield a bosonic theory. But if the gravitational anomaly only vanishes mod 8, then only gauging $(-1)^F$ is allowed, and the result is a fermionic theory. Our goal is to understand in detail how this happens, despite the fact $(-1)^F$ is defined in terms of shiftin…

This https://arxiv.org/abs/2312.16059 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Self-gravitating Higgs field of scalar charge
The self-gravitating Higgs field of a scalar charge has been studied. It is shown that in the zero and first approximation of the smallness of the scalar charge, the gravitational field of the scalar charge is described by the Schwarzschild-de Sitter metric with a cosmological constant determined by the vacuum potential of the Higgs field. An equation for the perturbation of the vacuum potential is obtained and studied. Particular exact solutions of the field equation are given. It is shown tha…

This https://arxiv.org/abs/2203.05889 has been replaced.
link: https://scholar.google.com/scholar?q=a

Addressing the Gravitational Wave - Collider Inverse Problem
We provide a roadmap for analyzing the interplay between hypothetical future collider observations and the detection of a gravitational wave signal produced by a strong first order electroweak phase transition in beyond the Standard Model (BSM) theories. A cornerstone of this roadmap is a combination of a dimensionally reduced, three-dimensional effective field theory and results of both perturbation theory and non-perturbative lattice simulations. For the first time we apply these state-of-the…

MHD Modeling of the Molecular Filament Evolution
I. M. Sultanov, S. A. Khaibrakhmanov
https://arxiv.org/abs/2405.02930 https://arxiv.…

MHD Modeling of the Molecular Filament Evolution
We perform numerical magnetohydrodynamic (MHD) simulations of the gravitational collapse and fragmentation of a cylindrical molecular cloud with the help of the FLASH code. The cloud collapses rapidly along its radius without any signs of fragmentation in the simulations without magnetic field. The radial collapse of the cloud is stopped by the magnetic pressure gradient in the simulations with parallel magnetic field. Cores with high density form at the cloud ends during further evolution. The…

Gravitational lensing by a Lorentz-violating black hole
A. A. Ara\'ujo Filho, J. R. Nascimento, A. Yu. Petrov, P. J. Porf\'irio
https://arxiv.org/abs/2404.04176

Gravitational lensing by a Lorentz-violating black hole
In this work, we study the gravitational lensing by a Lorentz-violating (LV) black hole inspired by the recent contribution [1]. Explicitly, we concentrate on a specific application: we perform the computation of gravitational lensing effects under the strong field limit. In particular, we analytically derive the deflection angle so that the lens equation can also be addressed. This methodological approach yields physically measurable outcomes, including the determination of relativistic image …

Correlated scalar perturbations and gravitational waves from axion inflation
Sofia P. Corb\`a, Lorenzo Sorbo
https://arxiv.org/abs/2403.03338 https://

Correlated scalar perturbations and gravitational waves from axion inflation
The scalar and tensor fluctuations produced during inflation can be correlated, if arising from the same underlying mechanism. In this paper we investigate such correlation in the model of axion inflation, where the rolling inflaton produces quanta of a $U(1)$ gauge field which, in turn, source scalar and tensor fluctuations. We compute the primordial correlator of the curvature perturbation, $ζ$, with the amplitude of the gravitational waves squared, $h_{ij}h_{ij}$, at frequencies probed by g…

This https://arxiv.org/abs/2403.15493 has been replaced.
initial toot: https://mastoxiv.page/@arX…

The ALPHA-g experiment, the hunt for gravitational dipoles and the quantum vacuum as the source of gravity in the Universe
More recently, the ALPHA-g experiment has shown that antiatoms fall in the Earth's gravitational field like ordinary atoms, with the non-negligible possibility that antiatoms fall with a slightly lower acceleration. A possible lower acceleration of antiatoms (which could be revealed with two orders of magnitude higher precision measurements) would be an epoch-making discovery and a window to a new physics, suggesting among other things that quarks and antiquarks have gravitational charges of op…

A bonafide model of structure formation from gravitational collapse
Koushiki, Dipanjan Dey, Pankaj S. Joshi
https://arxiv.org/abs/2404.03901 https://

A bonafide model of structure formation from gravitational collapse
This paper explores the cosmological implications of a scalar field with a specific potential, crucial for achieving the final equilibrium state of gravitational collapse. We consider a system with two fluids: minimally coupled matter representing dust-like dark matter and a scalar field acting as dark energy. Our model, akin to the top-hat collapse model, focuses on isolated over-dense regions within a closed FLRW metric, while the background follows a flat FLRW metric. We analyze spacetime co…

The effective field theory of multi-field inflationary fluctuations
Lucas Pinol
https://arxiv.org/abs/2405.02190 https://arxiv.org/pd…

The effective field theory of multi-field inflationary fluctuations
We build an effective field theory of multi-field inflationary fluctuations based on the adiabatic perturbation and on any number of matter fluctuations in the non-adiabatic sector, without imposing extra symmetries on the latter. Focusing on terms with at most two derivatives in fields' fluctuations, we argue that taking the decoupling limit -- in which gravitational interactions are neglected -- is justified in a quasi de Sitter spacetime with slow-varying Hubble scale. With these working hyp…

This https://arxiv.org/abs/2311.09156 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hept…

Radiative Asymptotic Symmetries of 3D Einstein-Maxwell Theory
We study the null asymptotic structure of Einstein-Maxwell theory in three-dimensional (3D) spacetimes. Although devoid of bulk gravitational degrees of freedom, the system admits a massless photon and can therefore accommodate electromagnetic radiation. We derive fall-off conditions for the Maxwell field that contain both Coulombic and radiative modes with non-vanishing news. The latter produces non-integrability and fluxes in the asymptotic surface charges, and gives rise to a non-trivial 3D …

On the inefficiency of fermion level-crossing under the parity-violating spin-2 gravitational field
Kohei Kamada, Jun'ya Kume
https://arxiv.org/abs/2404.19726 https://arxiv.org/pdf/2404.19726
arXiv:2404.19726v1 Announce Type: new
Abstract: Gravitational chiral anomaly connects the topological charge of spacetime and the chirality of fermions. It has been known that the chirality is carried by the particles (or the excited states) and also by vacuum. While the gravitational anomaly equation has been applied to cosmology, distinction between these two contributions has been rarely discussed. In the study of gravitational leptogenesis, for example, lepton asymmetry associated with the chiral gravitational waves sourced during inflation is evaluated only by integrating the anomaly equation. How these two contributions are distributed has not been seriously investigated. Meanwhile, a dominance of vacuum contribution is observed in some specific types of Bianchi spacetime with parity-violating gravitational fields, whose application to cosmology is not straightforward. One may wonder whether such a vacuum dominance takes place also in the system with chiral gravitational waves around the flat background, which is more suitable for application to realistic cosmology. In this work, we apply an analogy between U(1) electromagnetism and the weak gravity to the spacetime that resembles the one considered in the gravitational leptogenesis scenario. This approach allows us to obtain intuitive understanding of the fermion chirality generation under the parity-violating spin-2 gravitational field. By assuming the emergence of Landau level-like dispersion relation in our setup, we conjecture that level-crossing does not seem to be efficient while the charge accumulation in the vacuum likely takes place. Phenomenological implication is also discussed in the context of gravitational leptogenesis.

Status Report on Global Pulsar-Timing-Array Efforts to Detect Gravitational Waves
Joris P. W. Verbiest, Sarah J. Vigeland, Nataliya K. Porayko, Siyuan Chen, Daniel J. Reardon
https://arxiv.org/abs/2404.19529

Status Report on Global Pulsar-Timing-Array Efforts to Detect Gravitational Waves
The stability of the spin of pulsars and the precision with which these spins can be determined, allows many unique tests of interest to physics and astrophysics. Perhaps the most challenging and revolutionary of these, is the detection of nanohertz gravitational waves. An increasing number of efforts to detect and study long-period gravitational waves by timing an array of pulsars have been ongoing for several decades and the field is moving ever closer to actual gravitational-wave science. In…

This https://arxiv.org/abs/1712.10045 has been replaced.
link: https://scholar.google.com/scholar?q=a

Nonlinear stability of self-gravitating massive fields
We consider the global evolution problem for Einstein's field equations in the near-Minkowski regime and study the long-time dynamics of a massive scalar field evolving under its own gravitational field. We establish the existence of a globally hyperbolic Cauchy development associated with any initial data set that is sufficiently close to a data set in Minkowski spacetime. In addition to applying to massive fields, our theory allows us to cover metrics with slow decay in space. The strategy of…

Simulating Holographic Conformal Field Theories on Hyperbolic Lattices
Santanu Dey, Anffany Chen, Pablo Basteiro, Alexander Fritzsche, Martin Greiter, Matthias Kaminski, Patrick M. Lenggenhager, Rene Meyer, Riccardo Sorbello, Alexander Stegmaier, Ronny Thomale, Johanna Erdmenger, Igor Boettcher
https://arxiv.org/abs/2404.03062…

Simulating Holographic Conformal Field Theories on Hyperbolic Lattices
We demonstrate how table-top settings combining hyperbolic lattices with nonlinear dynamics universally lead to a genuine realization of the bulk-boundary-correspondence between gravity in anti-de-Sitter (AdS) space and conformal field theory (CFT). Our concrete and broadly applicable holographic toy model simulates gravitational self-interactions in the bulk and features an emergent CFT with nontrivial correlations on the boundary. We measure the CFT data contained in the two- and three-point …

This https://arxiv.org/abs/2307.01911 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Dynamical system analysis in multiscalar-torsion cosmology
We explore the phase-space of a multiscalar-torsion gravitational theory within a cosmological framework characterized by a spatially flat Friedmann-Lema\^ıtre-Robertson-Walker model. Our investigation focuses on teleparallelism and involves a gravitational model featuring two scalar fields, where one scalar field is coupled to the torsion scalar. We consider coupling in the two scalar fields' kinetic and potential components. We employ exponential functions for the scalar field potentials and…

Gravitational field due a moving Schwarzschild object
Ranchhaigiri Brahma, A. K. Sen
https://arxiv.org/abs/2405.01932 https://arxiv.o…

Gravitational field due a moving Schwarzschild object
In this paper we analyze the spacetime geometry due to a Schwarzschild object having accelerated motion. In the beginning we investigated the gravitational field due to a uniformly moving Schwarzschild object and obtained the spacetime line element for such an object. After analyzing the necessary boundary conditions the obtained line element is found to be consistent. Next we extended our work to a uniformly accelerated Schwarzschild object. In that case we obtained the spacetime line element …

On the properties and implications of collapse-driven MHD turbulence
Enrique V\'azquez-Semadeni, Yue Hu, Siyao Xu, Rub\'en Guerrero-Gamboa, Alex Lazarian
https://arxiv.org/abs/2403.00744

On the properties and implications of collapse-driven MHD turbulence
We numerically investigate the driving of MHD turbulence by gravitational contraction using simulations of an initially spherical, magnetically supercritical cloud core with initially transonic and trans-Alfvénic turbulence. We perform a Helmholtz decomposition of the velocity field, and investigate the evolution of its solenoidal and compressible parts, as well as of the velocity component along the gravitational acceleration vector, a proxy for the infall component of the velocity field. We …

Gravitational algebras and the generalized second law
Thomas Faulkner, Antony J. Speranza
https://arxiv.org/abs/2405.00847 https://ar…

Gravitational algebras and the generalized second law
We derive the generalized second law (GSL) for arbitrary cuts of Killing horizons from the perspective of crossed-product gravitational algebras, making use of a recent proposal by one of us for the construction of local gravitational algebras. This construction relies on the existence of a state whose modular flow is geometric on the horizon. In both free and interacting quantum field theories, such states are guaranteed to exist by the properties of half-sided translations on the horizon. Usi…

Series A, Episode 05 - The Web
ZEN: Sensors register increasing gravitational influence. Field strength now eight point six.
BLAKE: We're moving closer into the planet. [He moves to the navigation position] Vila, I want a new course. Locate the centre of that gravitational field. I want an attitude that takes us directly away from it.
https://blake.torpidity.net/s/105/209 📺 B7BA

Probing Stochastic Ultralight Dark Matter with Space-based Gravitational-Wave Interferometers
Yue-Hui Yao, Yong Tang
https://arxiv.org/abs/2404.01494 https…

Probing Stochastic Ultralight Dark Matter with Space-based Gravitational-Wave Interferometers
Ultralight particles are theoretically well-motivated dark matter candidates. In the vicinity of the solar system, these ultralight particles are described as a superposition of plane waves, resulting in a stochastic field with amplitude fluctuations on scales determined by the velocity dispersion of dark matter. In this work, we systematically investigate the sensitivity of space-based gravitational-wave interferometers to the stochastic ultralight dark matter field within the frequentist fram…

Possible Causes of False General Relativity Violations in Gravitational Wave Observations
Anuradha Gupta, K. G. Arun, Enrico Barausse, Laura Bernard, Emanuele Berti, Sajad A. Bhat, Alessandra Buonanno, Vitor Cardoso, Shun Yin Cheung, Teagan A. Clarke, Sayantani Datta, Arnab Dhani, Jose Mar\'ia Ezquiaga, Ish Gupta, Nir Guttman, Tanja Hinderer, Qian Hu, Justin Janquart, Nathan K. Johnson-McDaniel, Rahul Kashyap, N. V. Krishnendu, Paul D. Lasky, Andrew Lundgren, Elisa Maggio, Parthapr…

Possible Causes of False General Relativity Violations in Gravitational Wave Observations
General relativity (GR) has proven to be a highly successful theory of gravity since its inception. The theory has thrivingly passed numerous experimental tests, predominantly in weak gravity, low relative speeds, and linear regimes, but also in the strong-field and very low-speed regimes with binary pulsars. Observable gravitational waves (GWs) originate from regions of spacetime where gravity is extremely strong, making them a unique tool for testing GR, in previously inaccessible regions of …

On the properties and implications of collapse-driven MHD turbulence
Enrique V\'azquez-Semadeni, Yue Hu, Siyao Xu, Rub\'en Guerrero-Gamboa, Alex Lazarian
https://arxiv.org/abs/2403.00744

On the properties and implications of collapse-driven MHD turbulence
We numerically investigate the driving of MHD turbulence by gravitational contraction using simulations of an initially spherical, magnetically supercritical cloud core with initially transonic and trans-Alfvénic turbulence. We perform a Helmholtz decomposition of the velocity field, and investigate the evolution of its solenoidal and compressible parts, as well as of the velocity component along the gravitational acceleration vector, a proxy for the infall component of the velocity field. We …

This https://arxiv.org/abs/2403.04683 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Propagation and emission of gravitational waves in the weak-field limit within the Palatini formalism
In the era of gravitational waves physics, when detections of wave fronts are increasing in number, sensibility, frequencies and distances, gravitational physics has entered a period of maximum activity and brilliance. This has open a new window where General Relativity can be challenged in both weak as strong-field regimes. In this paper, we focus on the analysis of gravitational waves propagation and emission in the weak-field regime for gravitational theories within the Palatini formalism. O…

Impact of Black Hole Parameters on Photon Sphere and Shadow Radius: New Analytical Approach
Vitalii Vertogradov, Ali \"Ovg\"un
https://arxiv.org/abs/2404.04046

Impact of Black Hole Parameters on Photon Sphere and Shadow Radius: New Analytical Approach
In this letter, we present a novel approach to investigate the behavior of the photon sphere and shadow radius. Our method leverages extended gravitational decoupling and unveils two key analytic results. First, the additional matter field alters the photon sphere radius: it increases if $g'(r_{ph}^{(0)})>0$ and decreases if $g'(r_{ph}^{(0)})<0$ (where $g'$ represents the derivative of a specific metric function evaluated at the original photon sphere radius). Second, the presence of the matter…

Phase field modelling of the detachment of bubbles from a solid substrate
Carlos Uriarte, Marco A. Fontelos, Manuel Array\'a% s
https://arxiv.org/abs/2403.12246

Phase field modelling of the detachment of bubbles from a solid substrate
We develop and implement numerically a phase field model for the evolution and detachment of a gas bubble resting on a solid substrate and surrounded by a viscous liquid. The bubble has a static contact angle $θ$ and will be subject to gravitational forces. We compute, as a function of the static contact angle, the cricital Bond number over which bubbles detach from the substrate. Then, we perform similar studies for bubble resting on inclined substrates and bubbles under the action of an exte…

Graviton mass due to dark energy as a superconducting medium: theoretical and phenomenological aspects
Nader Inan, Ahmed Farag Ali, Kimet Jusufi, Abdelrahman Yasser
https://arxiv.org/abs/2404.03872

Graviton mass due to dark energy as a superconducting medium: theoretical and phenomenological aspects
It is well known that the cosmological constant term in the Einstein field equations can be interpreted as a stress tensor for dark energy. This stress tensor is formally analogous to an elastic constitutive equation in continuum mechanics. As a result, the cosmological constant leads to a "shear modulus" and "bulk modulus" affecting all gravitational fields in the universe. The form of the constitutive equation is also analogous to the London constitutive equation for a superconductor. Treatin…

A complex geometric perspective on a,c anomalies
Brian R Williams
https://arxiv.org/abs/2404.16128 https://arxiv.org/pdf/2404.16128…

A complex geometric perspective on a,c anomalies
In four-dimensional conformal field theory, the numbers a and c are defined as coefficients of particular terms in the operator product expansion (OPE) of the energy-momentum tensor. With supersymmetry there are relations between these coefficients and mixed R-symmetry and gravitational anomalies. In this paper we prove a relationship between these coefficients and anomalies to holomorphic reparametrization symmetry at the level of the holomorphic twist.

Background information: a study on the sensitivity of astrophysical gravitational-wave background searches
Arianna I. Renzini, Thomas A. Callister, Katerina Chatziioannou, Will M. Farr
https://arxiv.org/abs/2403.14793

Background information: a study on the sensitivity of astrophysical gravitational-wave background searches
The vast majority of gravitational-wave signals from stellar-mass compact binary mergers are too weak to be individually detected with present-day instruments and instead contribute to a faint, persistent background. This astrophysical background is targeted by searches that model the gravitational-wave ensemble collectively with a small set of parameters. The traditional search models the background as a stochastic field and estimates its amplitude by cross-correlating data from multiple inter…

This https://arxiv.org/abs/2402.18604 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Dynamics of holographic dark energy with apparent-horizon cutoff and non-minimal derivative coupling gravity in non-flat FLRW universe
Background cosmological dynamics for a universe with matter, a scalar field non-minimally derivative coupling to Einstein tensor under power-law potential and holographic vacuum energy is considered here. The holographic IR cutoff scale is apparent horizon which, for accelerating universe, forms a trapped null surface in the same spirit as blackhole's event horizon. For non-flat case, effective gravitational constant can not be expressed in the Friedmann equation. Therefore holographic vacuum d…

Gravitational Duals from Equations of State
Yago Bea, Raul Jimenez, David Mateos, Shuheng Liu, Pavlos Protopapas, Pedro Taranc\'on-\'Alvarez, Pablo Tejerina-P\'erez
https://arxiv.org/abs/2403.14763

Gravitational Duals from Equations of State
Holography relates gravitational theories in five dimensions to four-dimensional quantum field theories in flat space. Under this map, the equation of state of the field theory is encoded in the black hole solutions of the gravitational theory. Solving the five-dimensional Einstein's equations to determine the equation of state is an algorithmic, direct problem. Determining the gravitational theory that gives rise to a prescribed equation of state is a much more challenging, inverse problem. We…

Determining the difference between local acceleration and local gravity: applications of the equivalence principle to relativistic trajectories
Steven A. Balbus
https://arxiv.org/abs/2403.03965

Determining the difference between local acceleration and local gravity: applications of the equivalence principle to relativistic trajectories
We show by direct calculation that the common Equivalence Principle explanation for why gravity must deflect light is quantitatively incorrect by a factor of three in Schwarzschild geometry. It is therefore possible, at least as a matter of principle, to tell the difference between local acceleration and a true gravitational field by measuring the local deflection of light. We calculate as well the deflection of test particles of arbitrary energy, and construct a leading-order coordinate transf…

This https://arxiv.org/abs/2304.04281 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Time dilation of quantum clocks in a Newtonian gravitational field
We consider two non-relativistic quantum clocks interacting with a Newtonian gravitational field produced by a spherical mass. In the framework of Page and Wootters approach, we derive a time dilation for the time states of the clocks. The delay is in agreement up to first order with the gravitational time dilation obtained from the Schwarzschild metric. This result can be extended by considering the relativistic gravitational potential: in this case we obtain the agreement with the exact Schwa…

This https://arxiv.org/abs/2307.03724 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hepp…

Challenges in Interpreting the NANOGrav 15-Year Data Set as Early Universe Gravitational Waves Produced by ALP Induced Instability
In this paper, we study a possible early universe source for the recent observation of a stochastic gravitational wave background at the NANOGrav pulsar timing array. The source is a tachyonic instability in a dark gauge field induced by an axion-like particle (ALP), a known source for gravitational waves. We find that relative to the previous analysis with the NANOGrav 12.5-year data set, the current 15-year data set favors parameter space with a relatively larger axion mass and decay constant…

This https://arxiv.org/abs/2404.13684 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hept…

Generalized Entanglement Capacity of de Sitter Space
Near horizons, quantum fields of low spin exhibit densities of states that behave asymptotically like 1+1 dimensional conformal field theories. In effective field theory, imposing some short-distance cutoff, one can compute thermodynamic quantities associated with the horizon, and the leading cutoff sensitivity of the heat capacity is found to equal to the leading cutoff sensitivity of the entropy. One can also compute contributions to the thermodynamic quantities from the gravitational path in…

This https://arxiv.org/abs/2307.13374 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Classical radiation fields for scalar, electromagnetic, and gravitational waves with spacetime-symmetry breaking
An effective field theory framework is used to investigate some Lorentz-violating effects on the generation of electromagnetic and gravitational waves, complementing previous work on propagation. Specifically we find solutions to a modified, anisotropic wave equation, sourced by charge or fluid matter. We derive the radiation fields for scalars, classical electromagnetic radiation, and partial results for gravitational radiation. For gravitational waves, the results show longitudinal and breath…

This https://arxiv.org/abs/2401.08370 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_qu…

Digital quantum simulation of gravitational optomechanics with IBM quantum computers
We showcase the digital quantum simulation of the action of a Hamiltonian that governs the interaction between a quantum mechanical oscillator and an optical field, generating quantum entanglement between them via gravitational effects. This is achieved by making use of a boson-qubit mapping protocol and a digital gate decomposition that allow us to run the simulations in the quantum computers available in the IBM Quantum platform. We present the obtained results for the fidelity of the experim…

This https://arxiv.org/abs/2403.04617 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Tensor bispectrum mediated by an excited scalar field during inflation
We calculate the tensor bispectrum mediated by an excited scalar field during inflation and find that the bispectrum peaks in the squeezed configuration, which is different from that of gravitational waves induced by enhanced curvature perturbations re-entering the horizon in the radiation-dominated era. Measuring the bispectrum provides a promising way to distinguish the stochastic gravitational-wave background generated during inflation from that generated after inflation.

This https://arxiv.org/abs/2303.17518 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Constraining a relativistic mean field model using neutron star mass-radius measurements I: Nucleonic models
Measurements of neutron star mass and radius or tidal deformability deliver unique insight into the equation of state (EOS) of cold dense matter. EOS inference is very often done using generalized parametric or non-parametric models which deliver no information on composition. In this paper we consider a microscopic nuclear EOS model based on a field theoretical approach. We show that current measurements from NICER and gravitational wave observations constrain primarily the symmetric nuclear m…

Gravitational wave signatures of post-fragmentation reheating
Marcos A. G. Garcia, Mathias Pierre
https://arxiv.org/abs/2404.16932 https://

Gravitational wave signatures of post-fragmentation reheating
After cosmic inflation, coherent oscillations of the inflaton field about a monomial potential $V(ϕ)\sim ϕ^k$ result in an expansion phase characterized by a stiff equation-of-state $w\simeq(k-2)/(k+2)$. Sourced by the oscillating inflaton condensate, parametric (self)resonant effects can induce the exponential growth of inhomogeneities eventually backreacting and leading to the fragmentation of the condensate. In this work, we investigate realizations of inflation giving rise to such dynamic…

This https://arxiv.org/abs/2210.10790 has been replaced.
link: https://scholar.google.com/scholar?q=a

Strong Lensing by Galaxies
Strong gravitational lensing at the galaxy scale is a valuable tool for various applications in astrophysics and cosmology. The primary uses of galaxy-scale lensing are to study elliptical galaxies' mass structure and evolution, constrain the stellar initial mass function, and measure cosmological parameters. Since the discovery of the first galaxy-scale lens in the 1980s, this field has made significant advancements in data quality and modeling techniques. In this review, we describe the most …

Gravito-magnetic Polarization of Schwarzschild Black Hole
Tomer Hadad, Barak Kol, Michael Smolkin
https://arxiv.org/abs/2402.16172 https://

Gravito-magnetic Polarization of Schwarzschild Black Hole
We determine the gravito-magnetic Love numbers of non-rotating black holes in all spacetime dimensions through a novel and direct derivation. The Ishibashi- Kodama master field and its associated field equation are avoided. The matching to the EFT variables is simple. This method allows us to correct the values in the literature. Moreover, we highlight a parity-based selection rule for nonlinear terms that include both electric-type and magnetic-type gravitational field tensors, enabling us to …

Gravitational wave signatures of post-fragmentation reheating
Marcos A. G. Garcia, Mathias Pierre
https://arxiv.org/abs/2404.16932 https://

Gravitational wave signatures of post-fragmentation reheating
After cosmic inflation, coherent oscillations of the inflaton field about a monomial potential $V(ϕ)\sim ϕ^k$ result in an expansion phase characterized by a stiff equation-of-state $w\simeq(k-2)/(k+2)$. Sourced by the oscillating inflaton condensate, parametric (self)resonant effects can induce the exponential growth of inhomogeneities eventually backreacting and leading to the fragmentation of the condensate. In this work, we investigate realizations of inflation giving rise to such dynamic…

Imprints of Supermassive Black Hole Evolution on the Spectral and Spatial Anisotropy of Nano-Hertz Stochastic Gravitational-Wave Background
Mohit Raj Sah, Suvodip Mukherjee, Vida Saeedzadeh, Arif Babul, Michael Tremmel, Thomas R. Quinn
https://arxiv.org/abs/2404.14508

Imprints of Supermassive Black Hole Evolution on the Spectral and Spatial Anisotropy of Nano-Hertz Stochastic Gravitational-Wave Background
The formation and evolution of supermassive black holes (SMBHs) remains an open question in the field of modern cosmology. The detection of nanohertz (n-Hz) gravitational waves via pulsar timing arrays (PTAs) in the form of individual events and the stochastic gravitational wave background (SGWB) offers a promising avenue for studying SMBH formation across cosmic time, with SGWB signal being the immediately detectable signal with the currently accessible telescope sensitivities. By connecting t…

Gravito-magnetic Polarization of Schwarzschild Black Hole
Tomer Hadad, Barak Kol, Michael Smolkin
https://arxiv.org/abs/2402.16172 https://

Gravito-magnetic Polarization of Schwarzschild Black Hole
We determine the gravito-magnetic Love numbers of non-rotating black holes in all spacetime dimensions through a novel and direct derivation. The Ishibashi- Kodama master field and its associated field equation are avoided. The matching to the EFT variables is simple. This method allows us to correct the values in the literature. Moreover, we highlight a parity-based selection rule for nonlinear terms that include both electric-type and magnetic-type gravitational field tensors, enabling us to …

This https://arxiv.org/abs/2306.02464 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Graviton Mass Bounds in Very Special Relativity from Binary Pulsar's Gravitational Waves
In this work we study the gravitational radiation produced by a keplerian binary system within the context of Very Special Linear Gravity (VSLG), a novel theory of linearized gravity in the framework of Very Special Relativity (VSR) allowing for a gauge-invariant mass $m_g$ of the graviton. For this task, we exploit Effective Field Theory's techniques, which require, among others, the calculation of the squared amplitude of the emission process and therefore the polarization sum for VSLG gravit…

Exploring field-evolution and dynamical-capture coalescing binary black holes in GWTC-3
Yin-Jie Li, Shao-Peng Tang, Shi-Jie Gao, Dao-Cheng Wu, Yuan-Zhu Wang
https://arxiv.org/abs/2404.09668

Exploring field-evolution and dynamical-capture coalescing binary black holes in GWTC-3
The continuously expanding sample of gravitational-wave observations is revealing the formation and evolutionary mechanism of merging compact binaries. Two primary channels, namely, isolated field binary evolution and dynamical capture, are widely accepted as potential producers of merging binary black holes (BBHs), which are distinguishable with the spin-orientation distributions of the BBHs. We investigate the two formation channels in GWTC-3, with a dedicated semi-parametric population model…

The Tolman-Ehrenfest effect for an ideal gas in a background of time-independent electric, magnetic, and gravitational fields
H. Arthur Weldon
https://arxiv.org/abs/2403.18652

The Tolman-Ehrenfest effect for an ideal gas in a background of time-independent electric, magnetic, and gravitational fields
The statistical mechanics of an ideal gas of point particles moving in a time independent background metric with $g_{0j}\neq 0$ is investigated. An explicit calculation shows that when there is no background electrostatic or magnetostatic field the thermodynamic pressure, energy density, and thermally averaged energy-momentum tensor depend on temperature and chemical potential only through the ratios $T_{0}/\sqrt{g_{00}}$ and $μ_{0}/\sqrt{g_{00}}$. A background magnetostatic field does not cha…

Linear dynamics and classical tests of the gravitational quantum field theory
Yuan-Kun Gao, Da Huang, Yong-Liang Ma, Yong Tang, Yue-Liang Wu, Yu-Feng Zhou
https://arxiv.org/abs/2403.17619

Linear dynamics and classical tests of the gravitational quantum field theory
We explore the new physics phenomena of gravidynamics governed by the inhomogeneous spin gauge symmetry based on the gravitational quantum field theory. Such a gravidynamics enables us to derive the generalized Einstein equation and an equation beyond it. To simplify the analyses, we linearize the dynamic equations of gravitational interaction by keeping terms up to the leading order in the dual gravigauge field. We then apply the linearized dynamic equations into two particular gravitational p…

This https://arxiv.org/abs/2307.03249 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Single field inflation in the light of Pulsar Timing Array Data: Quintessential interpretation of blue tilted tensor spectrum through Non-Bunch Davies initial condition
In this work, we present a quintessential interpretation of having a blue-tilted tensor power spectrum for canonical single-field slow-roll inflation to explain the recently observed Pulsar Timing Array (NANOGrav 15-year and EPTA) signal of Gravitational Waves (GW). We formulate the complete semi-classical description of cosmological perturbation theory in terms of scalar and tensor modes using the Non-Bunch Davies initial condition. We found that the existence of the blue tilt ($n_t$) within t…

Gravitational Wave Probe of Gravitational Dark Matter from Preheating
Ruopeng Zhang, Sibo Zheng
https://arxiv.org/abs/2403.09089 https://

Gravitational Wave Probe of Gravitational Dark Matter from Preheating
Following our previous studies on gravitational dark matter (GDM) production in the early Universe of preheating,we forecast high-frequency gravitational wave (GW) spectra as the indirect probe of such GDM. We use proper lattice simulations to handle the resonance,and to solve the GW equation of motion with resonance induced scalar field excitations as the source term.Our numerical results show that the Higgs scalar excitations in the Higgs preheating model give rise to magnitudes of GW energy …

Effects of $f(\mathcal{R},\mathcal{T},\mathcal{R}_{\gamma\upsilon}\mathcal{T}^{\gamma\upsilon})$ Gravity on Anisotropic Charged Compact Structures
M. Sharif, T. Naseer
https://arxiv.org/abs/2403.00253

Effects of $f(\mathcal{R},\mathcal{T},\mathcal{R}_{γ\upsilon}\mathcal{T}^{γ\upsilon})$ Gravity on Anisotropic Charged Compact Structures
This paper focuses on the analysis of static spherically symmetric anisotropic solutions in the presence of electromagnetic field through the gravitational decoupling approach in $f(\mathcal{R},\mathcal{T},\mathcal{R}_{γ\upsilon}\mathcal{T}^{γ\upsilon})$ gravity. We use geometric deformation only on radial metric function and obtain two sets of the field equations. The first set deals with isotropic fluid while the second set yields the influence of anisotropic source. We consider the modifie…

Exploring Primordial Black Holes and Gravitational Waves with R-Symmetric GUT Higgs Inflation
Nadir Ijaz, Mansoor Ur Rehman
https://arxiv.org/abs/2402.13924

Exploring Primordial Black Holes and Gravitational Waves with R-Symmetric GUT Higgs Inflation
This study investigates the realization of R-symmetric Higgs inflation within the framework of no-scale-like supergravity, aiming to elucidate the formation of primordial black holes and observable gravitational waves within a class of GUT models. We explore the possibility of an ultra-slow-roll phase in a hybrid inflation framework, where the GUT Higgs field primarily takes on the role of the inflaton. The amplification of the scalar power spectrum gives rise to scalar-induced gravitational wa…

This https://arxiv.org/abs/2311.05380 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Quasinormal spectrum in the asymptotically safe gravity
Asymptotically safe gravity is based on the idea of the dependence of the gravitational coupling upon the distance from the origin, approaching its classical value in the weak field regime. We consider three cases of identifying the cut-off parameter in the asymptotically safe gravity, leading to the three distinctive models for black holes. We find that the deviation of the fundamental mode from the Schwarzschild limit is a few percent, in contrast to the higher overtones, where the deviation …

This https://arxiv.org/abs/2311.05380 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Quasinormal spectrum in the asymptotically safe gravity
Asymptotically safe gravity is based on the idea of the dependence of the gravitational coupling upon the distance from the origin, approaching its classical value in the weak field regime. We consider three cases of identifying the cut-off parameter in the asymptotically safe gravity, leading to the three distinctive models for black holes. We find that the deviation of the fundamental mode from the Schwarzschild limit is a few percent, in contrast to the higher overtones, where the deviation …

Exploring Primordial Black Holes and Gravitational Waves with R-Symmetric GUT Higgs Inflation
Nadir Ijaz, Mansoor Ur Rehman
https://arxiv.org/abs/2402.13924

Exploring Primordial Black Holes and Gravitational Waves with R-Symmetric GUT Higgs Inflation
This study investigates the realization of R-symmetric Higgs inflation within the framework of no-scale-like supergravity, aiming to elucidate the formation of primordial black holes and observable gravitational waves within a class of GUT models. We explore the possibility of an ultra-slow-roll phase in a hybrid inflation framework, where the GUT Higgs field primarily takes on the role of the inflaton. The amplification of the scalar power spectrum gives rise to scalar-induced gravitational wa…

Effects of gravitational particle production on Higgs portal dark matter
Soichiro Izumine, Kazunori Nakayama
https://arxiv.org/abs/2403.05199 https://

Effects of gravitational particle production on Higgs portal dark matter
The gravitational interaction is ubiquitous and the effect of gravitational particle production necessarily contributes to the dark matter abundance. A simple candidate of dark matter is a scalar particle, whose only renormalizable interaction is the Higgs portal coupling. We show that the abundance of Higgs portal dark matter is significantly affected by the gravitational production effect. In particular, the gravitational production from the coherently oscillating inflaton field during the re…

This https://arxiv.org/abs/2305.00877 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Novel high-frequency gravitational waves detection with split cavity
Gravitational waves can generate electromagnetic effects inside a strong electric or magnetic field within the Standard Model and general relativity. Here we propose using a quarterly split cavity and LC(inductor and capacitor)-resonance circuit to detect a high-frequency gravitational wave from 0.1 MHz to GHz. We perform a full 3D simulation of the cavity's signal for sensitivity estimate. Our sensitivity depends on the coherence time scale of the high-frequency gravitational wave sources and …

This https://arxiv.org/abs/2312.07295 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Gravitational atoms in the braneworld scenario
In the Randall-Sundrum (RS) II braneworld scenario, general relativity (GR) is modified by adding an extra dimension such that it is indistinguishable from GR in the weak gravity limit. However, such modifications may leave a mark in the strong field regime. We therefore analyze massive scalar perturbations around rotating black holes in the RS II model. Unlike black holes in GR, these braneworld black holes carry a tidal charge that contains information about the extra spatial dimension, and t…

Gravitational signatures of ALP dark matter fragmentation
Aleksandr Chatrchyan, Cem Er\"oncel, Matthias Koschnitzke, G\'eraldine Servant
https://arxiv.org/abs/2402.10313 …

Gravitational signatures of ALP dark matter fragmentation
The misalignment mechanism for axion-like particles (ALPs) is a leading explanation for dark matter. In this work we investigate ALPs with non-periodic potentials, which allow for large misalignment of the field from the minimum and make it possible for ALPs to match the relic density of dark matter in a large part of the parameter space. Such potentials give rise to self-interactions which can trigger an exponential growth of fluctuations in the ALP field via parametric resonance, leading to t…

Gravitational Lensing of Galaxy Clustering
Brandon Buncher, Gilbert Holder, Selim Hotinli
https://arxiv.org/abs/2402.07988 https://ar…

Gravitational Lensing of Galaxy Clustering
We investigate lensing reconstruction using the clustered galaxy distribution as a source field, using both the traditional cosmic microwave background quadratic estimator and a shear-only estimator. We calculate the expected signal-to-noise ratio of the cross power spectrum of such reconstructions with cosmic shear measurements for an LSST-like galaxy survey. Modeling the galaxy field as a Gaussian random field, we find that there is substantial clustering signal in the source field at angular…

This https://arxiv.org/abs/2308.03645 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hept…

Island formula in Planck brane
Double holography offers a profound understanding of the island formula by describing a gravitational system on AdS$_d$ coupled to a conformal field theory on $\mathbb{R}^{1,d-1}$, dual to an AdS$_{d+1}$ spacetime with an end-of-the-world (EOW) brane. In this work, we extend the proposal in [A. Almheiri et al. JHEP 03 (2020) 149] by considering that the dual bulk spacetime has two EOW branes: one with a gravitational system and the other with a thermal bath. We demonstrate an equivalence betwee…

This https://arxiv.org/abs/2403.11301 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Can nonlocal gravity really explain dark energy?
In view to scrutinize the idea that nonlocal modifications of General Relativity could dynamically address the dark energy problem, we investigate the evolution of the Universe at infrared scales as an Infinite Derivative Gravity model of the Ricci scalar, without introducing the cosmological constant $Λ$ or any scalar field. The accelerated expansion of the late Universe is shown to be compatible with the emergence of nonlocal gravitational effects at sufficiently low energies. A technique fo…

This https://arxiv.org/abs/2310.19762 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Core and Halo Properties in Multi-Field Wave Dark Matter
In this work, we compute multi-field core and halo properties in wave Dark Matter models. We focus on the case where Dark Matter consists of two light (real) scalars, interacting gravitationally. As in the single-field Ultra Light Dark Matter (ULDM) case, the scalar field behaves as a coherent BEC with a definite ground state (at fixed total mass), often referred to in the literature as a gravitational soliton. We establish an efficient algorithm to find the ground and excited states of such tw…

This https://arxiv.org/abs/2310.06039 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hepp…

Rescuing Gravitational-Reheating in Chaotic Inflation
We show, within the single-field inflationary paradigm, that a linear non-minimal interaction $ξ\,M_P\,ϕ\,R$ between the inflaton field $ϕ$ and the Ricci scalar $R$ can result in successful inflation that concludes with an efficient heating of the Universe via perturbative decays of the inflaton, aided entirely by gravity. Considering the inflaton field to oscillate in a quadratic potential, we find that $\mathcal{O}(10^{-1}) \lesssim ξ\lesssim \mathcal{O}(10^2)$ is required to satisfy the …

This https://arxiv.org/abs/2304.09671 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Modified General Relativity and dark matter
Modified General Relativity (MGR) is the natural extension of General Relativity (GR). MGR explicitly uses the smooth regular line element vector field $(\bm{X},-\bm{X}) $, which exists in all Lorentzian spacetimes, to construct a connection-independent symmetric tensor that represents the energy-momentum of the gravitational field. It solves the problem of the non-localization of gravitational energy-momentum in GR, preserves the ontology of the Einstein equation, and maintains the equivalence…

High Frequency Gravitational Wave Bounds from Galactic Neutron Stars
Virgile Dandoy, Toni Bert\'olez-Mart\'inez, Francesco Costa
https://arxiv.org/abs/2402.14092

High Frequency Gravitational Wave Bounds from Galactic Neutron Stars
High-Frequency Gravitational Waves (HFGWs) constitute a unique window on the early Universe as well as exotic astrophysical objects. If the current gravitational wave experiments are more dedicated to the low frequency regime, the graviton conversion into photons in a strong magnetic field constitutes a powerful tool to probe HFGWs. In this paper, we show that neutron stars, due to their extreme magnetic field, are a perfect laboratory to study the conversion of HFGWs into photons. Using realis…

This https://arxiv.org/abs/2402.07969 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Photon-Gravity Coupling in Schwarzschild Spacetime
A canonical formalism for quantum electrodynamics in curved spacetime is developed. This formalism enables a systematic investigation of photons in the Schwarzschild gravitational field, yielding novel results as well as refining previous results that were predicted by heuristic methods. The claim that "the gravitational redshift is a shift in the sharp frequencies of the photons for all frequencies of the spectrum" is proved. It is shown the gravitational superposition decoherence is due to ph…

Constraining Self-interacting Scalar Field Dark Matter From the Black Hole Shadow of the Event Horizon Telescope
Gabriel G\'omez, Patrick Valageas
https://arxiv.org/abs/2403.08988

Constraining Self-interacting Scalar Field Dark Matter From the Black Hole Shadow of the Event Horizon Telescope
An exciting possibility to constrain dark matter (DM) scenarios is to search for their gravitational imprints on Black Hole (BH) observations. In this paper, we investigate the impact of self-interacting scalar field DM on the shadow radius of a Schwarzschild BH. We implement a self-consistent formulation, paying attention to the enhancement of the DM density due to the BH gravitational influence and the accretion flow onto the BH. First, we calculate the first-order correction to the shadow ra…

This https://arxiv.org/abs/2206.15333 has been replaced.
link: https://scholar.google.com/scholar?q=a

Classification of Gravitational Waves in Higher-dimensional Space-time and Possibility of Observation
The direct detection of gravitational waves opens the possibility to test general relativity and its alternatives in the strong field regime. Here we focus on the test of the existence of extra dimensions. The classification of gravitational waves in metric gravity theories according to their polarizations in higher-dimensional space-time and the possible observation of these polarizations in 3-dimensional subspace are discussed in this work. And we show that the difference in the response of g…

This https://arxiv.org/abs/2402.19459 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Anomalous contribution to galactic rotation curves due to stochastic spacetime
We consider a proposed alternative to quantum gravity, in which the spacetime metric is treated as classical, even while matter fields remain quantum. Consistency of the theory necessarily requires that the metric evolve stochastically. Here, we show that this stochastic behaviour leads to a modification of general relativity at low accelerations. In the low acceleration regime, the variance in the acceleration produced by the gravitational field is high in comparison to that produced by the Ne…

Non-local gravitational corrections in black hole shadow images
Stanislav Alexeyev, Artem Baiderin, Alexandra Nemtinova, Oleg Zenin
https://arxiv.org/abs/2404.16079

Non-local gravitational corrections in black hole shadow images
With the help of Newman-Janis method new spinning black hole (BH) solution for a non-local gravity model was obtained. We show how to account the quantum gravitational correction part in BH shadows modelling using spinning BH metrics with a model independent approach. It is confirmed that in the future to follow the increasing of the experimental accuracy and therefore to reproduce new results theoretically one could take into account different field correction terms instead of introducing of n…

Study of Charged Cylindrical Collapse in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ Gravity
M. Sharif, Tayyab Naseer
https://arxiv.org/abs/2405.00374 https:/…

Study of Charged Cylindrical Collapse in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ Gravity
This paper investigates the effects of electromagnetic field on the gravitational collapse in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ theory, where $\mathcal{Q} = \mathcal{R}_{φ\vartheta} \mathcal{T}^{φ\vartheta}$. For this, we assume dynamical cylindrically symmetric self-gravitating geometry which is coupled with generalized anisotropic matter distribution as well as dissipation flux. We adopt the model $\mathcal{R}+Φ\sqrt{\mathcal{T}}+Ψ\mathcal{Q}$ to formulate the corresponding dynamic…

Sound speed as a source of the gravitational field in modified gravity
P. P. Avelino
https://arxiv.org/abs/2404.12373 https://arxiv.o…

Sound speed as a source of the gravitational field in modified gravity
In the context of $f(R,T)$ gravity and other modified theories of gravity, the knowledge of the first order variation of the trace $T$ of the energy-momentum tensor with respect to the metric is essential for an accurate characterization of the gravitational field. In this paper, by considering a paradigmatic example of a perfect fluid whose dynamics is described by a pure k-essence matter Lagrangian in $f(R,T)=R+\mathcal F(T)$ gravity, we show that the first order variation of the trace of the…

This https://arxiv.org/abs/2308.12943 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Characterization of the gravitational wave spectrum from sound waves within the sound shell model
We compute the gravitational wave (GW) spectrum sourced by sound waves produced during a first-order phase transition in the radiation-dominated epoch. The correlator of the velocity field is evaluated in accordance with the sound shell model. In our derivation we include the effects of the expansion of the Universe, which are relevant in particular for sourcing processes whose time duration is comparable with the Hubble time. Our results show a causal growth at small frequencies, $Ω_{\rm GW} …

Impenetrable Barriers in the Phase Space of a Particle Around a Kerr Rotating Black Hole
Francisco Gonzalez Montoya
https://arxiv.org/abs/2403.19846 https:…

Impenetrable Barriers in the Phase Space of a Particle Around a Kerr Rotating Black Hole
We study the phase space of a particle in the gravitational field of a rotating black hole described by the Kerr metric from a geometrical perceptive. In particular, we show the construction of a multidimensional generalization of the unstable periodic orbits and their stable and unstable invariant manifolds that direct the dynamics in the phase space. Those stable and unstable invariant manifolds divide the phase space and are robust under perturbations. To visualize the multidimensional invar…

This https://arxiv.org/abs/2402.07965 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Extension of Theory of Gravitomagnetism and Spinor Quantum Mechanics with Dynamics of Free Electromagnetic Field
The theory of Gravitomagnetism and spinor quantum mechanics describing the interaction between the Dirac spinor field, the electromagnetic field, and a weak gravitational field is extended by including the Lagrangian density of the free electromagnetic field. It is shown that the newly added term in the Lagrangian density is necessary to restore a symmetric energy-momentum tensor in the interaction term of the Lagrangian density within the theory. We prove that when the electromagnetic energy t…

Some curvature properties of perfect fluid spacetimes
Krishnendu De, Uday Chand De, Ljubica Velimirovic
https://arxiv.org/abs/2402.15354 https://

Some curvature properties of perfect fluid spacetimes
In this paper we assume that a perfect fluid is the source of the gravitational field while analyzing the solutions to the Einstein field equations.

This https://arxiv.org/abs/2312.07486 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Dark energy from topology change induced by microscopic Gauss-Bonnet wormholes
It is known that the appearance of microscopic objects with distinct topologies and different Euler characteristics, such as instatons and wormholes, at the spacetime-foam level in Euclidean quantum gravity approaches, leads to spacetime topology changes. Such changes, in principle, may affect the field equations that arise through the semiclassical variation procedure of gravitational actions. Although in the case of Einstein-Hilbert action the presence of microscopic wormholes does not lead t…

This https://arxiv.org/abs/2310.11336 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Polarization modes of gravitational waves in general modified gravity: General metric theory and general scalar-tensor theory
In this paper, we establish a unified parameterized framework for analyzing the polarization modes of gravitational waves in the general metric theory (gravity is only described by the metric) and the general scalar-tensor theory (gravity is described by the metric and an additional scalar field). Specifically, we study the polarization modes of gravitational waves in the most general metric theory and general scalar-tensor theory that satisfy the following conditions: (1) Spacetime is four-dim…

Dark energy and dark matter configurations for wormholes and solitionic hierarchies of nonmetric Ricci flows and $F(R,T,Q,T_{m})$ gravity
Lauren\c{t}iu Bubuianu, Sergiu I. Vacaru, El\c{s}en Veli Veliev, Assel Zhamysheva
https://arxiv.org/abs/2402.19362

Dark energy and dark matter configurations for wormholes and solitionic hierarchies of nonmetric Ricci flows and $F(R,T,Q,T_{m})$ gravity
We extend the anholonomic frame and connection deformation method, AFCDM, for constructing exact and parametric solutions in general relativity, GR, to geometric flow models and modified gravity theories, MGTs, with nontrivial torsion and nonmetricity fields. Following abstract geometric or variational methods, we can derive corresponding systems of nonmetric gravitational and matter field equations which consist of very sophisticated systems of coupled nonlinear PDEs. Using nonholonomic frames…

Anomalous contribution to galactic rotation curves due to stochastic spacetime
Jonathan Oppenheim, Andrea Russo
https://arxiv.org/abs/2402.19459 https://…

Anomalous contribution to galactic rotation curves due to stochastic spacetime
We consider a proposed alternative to quantum gravity, in which the spacetime metric is treated as classical, even while matter fields remain quantum. Consistency of the theory necessarily requires that the metric evolve stochastically. Here, we show that this stochastic behaviour leads to a modification of general relativity at low accelerations. In the low acceleration regime, the variance in the acceleration produced by the gravitational field is high in comparison to that produced by the …

This https://arxiv.org/abs/2311.17130 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Wide Binaries and Modified Gravity (MOG)
Wide binary stars are used to test the modified gravity called Scalar-Tensor-Vector Gravity or MOG. This theory is based on the additional gravitational degrees of freedom, the scalar field $G=G_N(1+α)$, where $G_N$ is Newton's constant, and the massive (spin-1 graviton) vector field $ϕ_μ$. The wide binaries have separations of 2-30 kAU. The MOG acceleration law, derived from the MOG field equations and equations of motion of a massive test particle for weak gravitational fields, depends on …

This https://arxiv.org/abs/2403.16741 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Spherically symmetric configurations in the quadratic $f(R)$ gravity
We study spherically symmetric configurations of the quadratic $f(R)$ gravity in the Einstein frame. In case of a purely gravitational system, we have determined the global qualitative behavior of the metric and the scalaron field for all static solutions satisfying the conditions of asymptotic flatness. These solutions are proved to be regular everywhere except for a naked singularity at the center; they are uniquely determined by the total mass $\mathfrak{M}$ and the "scalar charge" $Q$ chara…

Self-gravitating Higgs field of scalar charge. II. Asymmetric scalar doublet
Yu. G. Ignat'ev
https://arxiv.org/abs/2403.10472 https://

Self-gravitating Higgs field of scalar charge. II. Asymmetric scalar doublet
The self-gravitating Higgs field of a scalar charge is studied for the case of an asymmetric scalar doublet containing, along with a canonical and a phantom component. It is shown that in the zero and first approximation of the smallness of the canonical and phantom scalar charges, the gravitational field of the scalar charge is described by the Schwarzschild-de Sitter metric with a cosmological constant determined by the stable equilibrium point - the vacuum potential of the canonical Higgs fi…

Self-gravitating Higgs field of scalar charge. II. Asymmetric scalar doublet
Yu. G. Ignat'ev
https://arxiv.org/abs/2403.10472 https://

Self-gravitating Higgs field of scalar charge. II. Asymmetric scalar doublet
The self-gravitating Higgs field of a scalar charge is studied for the case of an asymmetric scalar doublet containing, along with a canonical and a phantom component. It is shown that in the zero and first approximation of the smallness of the canonical and phantom scalar charges, the gravitational field of the scalar charge is described by the Schwarzschild-de Sitter metric with a cosmological constant determined by the stable equilibrium point - the vacuum potential of the canonical Higgs fi…

This https://arxiv.org/abs/2311.13497 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Gravitational fields of axially symmetric compact objects in 5D space-time-matter gravity
In the standard Einstein's theory the exterior gravitational field of any static and axially symmetric stellar object can be described by means of a single function from which we obtain a metric into a four-dimensional space-time. In this work we present a generalization of those so called Weyl solutions to a space-time-matter metric in a five-dimensional manifold within a non-compactified Kaluza-Klein theory of gravity. The arising field equations reduce to those of vacuum Einstein's gravity w…

Gravitational wave probes of Barrow cosmology with LISA standard sirens
Mahnaz Asghari, Alireza Allahyari, David F. Mota
https://arxiv.org/abs/2404.13025 h…

Gravitational wave probes of Barrow cosmology with LISA standard sirens
We study the Barrow cosmological model, which proposes that quantum gravity effects create a complex, fractal structure for the universe's apparent horizon. We leverage the thermodynamics - gravity conjecture. By applying the Clausius relation to the apparent horizon of the Friedmann - Lemaître - Robertson - Walker universe within this framework, we derive modified field equations where the Barrow entropy is linked to the horizon. We assess the Barrow cosmology against current observations - c…

This https://arxiv.org/abs/2307.02214 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Inflation in simple one-loop effective potentials of perturbative quantum gravity
We study inflation in scalar-tensor perturbative quantum gravity driven by a one-loop effective potential. We consider effective potentials generated by three models. The first model describes a single scalar field with a non-vanishing mass. The second model describes a massless scalar field with non-minimal coupling to the Einstein tensor. The third model generalises the Coleman-Weinberg model for the gravitational case. The first model can be consistent with the observational data for $N\sim …

Observational Constraints on the Maximum Masses of White Dwarfs, Neutron Stars, and Exotic Stars in Non-Minimal Derivative Coupling Gravity
M. D. Danarianto, I. Prasetyo, A. Suroso, B. E. Gunara, A. Sulaksono
https://arxiv.org/abs/2403.19450

Observational Constraints on the Maximum Masses of White Dwarfs, Neutron Stars, and Exotic Stars in Non-Minimal Derivative Coupling Gravity
The advancement of astronomical observations opens the possibility of testing our current understanding of gravitational theory in the strong-field regime and probing any deviation from general relativity. We explore to what extent compact stars predicted by non-minimal derivative coupling (NMDC) gravity theory agree with observed data. We investigate white dwarfs (WDs), neutron stars (NSs), and quark stars (QSs) mass and radius in various values of constant scalar $|Q_{\infty}|$ at c…

A Post-Newtonian Analysis of Regularized 4D-EGB Theory: Complete Set of PPN Parameters and Observational Constraints
J\'unior D. Toniato, Mart\'in G. Richarte
https://arxiv.org/abs/2402.13951

A Post-Newtonian Analysis of Regularized 4D-EGB Theory: Complete Set of PPN Parameters and Observational Constraints
We performed a post-Newtonian analysis of the regularized four-dimensional Einstein-Gauss-Bonnet gravitational theory (4D-EGB). The resulting metric differs from the classical parametrized post-Newtonian (PPN) formalism in that a new gravitational potential arises from the integration of the approximate field equations. We also investigated the conserved quantities and equations of motion for massive bodies and light rays to a certain degree. By computing the predicted periastron advance rate i…

A Coordinate-Independent Formalism for Detecting High-Frequency Gravitational Waves
Wolfram Ratzinger, Sebastian Schenk, Pedro Schwaller
https://arxiv.org/abs/2404.08572

A Coordinate-Independent Formalism for Detecting High-Frequency Gravitational Waves
In an external electric or magnetic field, a gravitational wave (GW) may be converted into electromagnetic radiation. We present a coordinate-invariant framework to describe the GW signal in a detector that is based on this effect, such as cavities for axion searches. In this framework, we pay special attention to the definition of manifestly coordinate-independent expressions for the electromagnetic fields that an external observer would detect. A careful assessment of the detector's perceived…

Spinfoams, $\gamma$-duality and parity violation in primordial gravitational waves
Eugenio Bianchi, Monica Rincon-Ramirez
https://arxiv.org/abs/2403.06053 …

Spinfoams, $γ$-duality and parity violation in primordial gravitational waves
The Barbero-Immirzi parameter $γ$ appears as a coupling constant in the spinfoam dynamics of loop quantum gravity and can be understood as a measure of gravitational parity violation via a duality rotation. We investigate an effective field theory for gravity and a scalar field, with dynamics given by a $γ$-dual action obtained via a duality rotation of a parity-non-violating one. The resulting relation between the coupling constants of parity-even and parity-odd higher-curvature terms is det…

Gravitational wave pulse and memory effects for hairy Kiselev black hole and its analogy with Bondi-Sachs formalism
H. Hadi, Amin Rezaei Akbarieh, David F. Mota
https://arxiv.org/abs/2404.08026

Gravitational wave pulse and memory effects for hairy Kiselev black hole and its analogy with Bondi-Sachs formalism
The investigation of non-vacuum cosmological backgrounds containing black holes is greatly enhanced by the Kiselev solution. This solution plays a crucial role in understanding the properties of the background and its relationship with the features of the black hole. Consequently, the gravitational memory effects at large distances from the black hole offer a valuable means of obtaining information about the surrounding field parameter N and parameters related to the hair of the hairy Kiselev B…

Optical appearance of black holes surrounded by a dark matter halo
Caio F. B. Macedo, Jo\~ao Lu\'is Rosa, Diego Rubiera-Garcia
https://arxiv.org/abs/2402.13047

Optical appearance of black holes surrounded by a dark matter halo
Black holes in General Relativity are described by space-time metrics that are simpler in comparison to non-vacuum compact objects. However, given the universality of the gravitational pull, it is expected that dark matter accumulates around astrophysical black holes, which can have an impact in the overall gravitational field, especially at galactic centers, and induce non-negligible effects in their observational imprints. In this work we study the optical appearance of a spherically symmetri…

$f(R,\square R)$-gravity and equivalency with the modified GUP Scalar field models
Andronikos Paliathanasis
https://arxiv.org/abs/2404.04519 https://

$f(R,\square R)$-gravity and equivalency with the modified GUP Scalar field models
Inspired by the generalization of scalar field gravitational models with a minimum length we study the equivalent theory in modified theories of gravity. The quadratic Generalized Uncertainty Principle (GUP) gives rise to a deformed Heisenberg algebra in the application, resulting in the emergence of additional degrees of freedom described by higher-order derivatives. The new degrees of freedom can be attributed to the introduction of a new scalar field, trasforming the resulting theory into a …

This https://arxiv.org/abs/2310.11041 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Weak-field regime of scalar-tensor theories with an instantaneous mode
Higher-order scalar-tensor theories having an instantaneous mode do not develop the Ostrogradsky instability even if a seemingly dangerous mode is present. Such theories satisfy only partially the degeneracy conditions that are usually imposed to remove the dangerous mode completely, and are dubbed as U-DHOST theories. We study weak gravitational fields sourced by nonrelativistic matter distributions in U-DHOST theories. In contrast to the case of totally degenerate theories where nonlinear der…

Towards a Consistent Calculation of the Lunar Response to Gravitational Waves
Han Yan, Xian Chen, Jinhai Zhang, Fan Zhang, Mengyao Wang, Lijing Shao
https://arxiv.org/abs/2403.08681

Towards a Consistent Calculation of the Lunar Response to Gravitational Waves
The recent increasing interest in detecting gravitational waves (GWs) by lunar seismic measurement urges us to have a clear understanding of the response of the moon to passing GWs. In this paper, we clarify the relationship between two seemly different response functions which have been derived previously using two different methods, one taking the field-theory approach and the other using the tidal force induced by GWs. We revisit their derivation and prove, by both analytical arguments and n…