Tootfinder

Non-local quantum field theory from doubly special relativity
J. J. Relancio, L. Santamar\'ia-Sanz
https://arxiv.org/abs/2403.18772 https://

Non-local quantum field theory from doubly special relativity
Non-local quantum field theories could be a solution to the inconsistencies arising when quantizing gravity. Doubly special relativity is regarded as a low-energy limit of a quantum gravity theory with testable predictions. We present a new formulation of quantum field theories in doubly special relativity with non-local behavior. Our construction restricts the models to those showing linear Lorentz invariance. The deformed Klein--Gordon, Dirac, and electromagnetic Lagrangians are derived. 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…

This https://arxiv.org/abs/2312.17053 has been replaced.
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Galaxy-galaxy lensing data: $f(T)$ gravity challenges General Relativity
We use galaxy-galaxy lensing data to test General Relativity and $f(T)$ gravity at galaxies scales. We consider an exact spherically symmetric solution of $f(T)$ theory which is obtained from an approximate quadratic correction, and thus it is expected to hold for every realistic deviation from General Relativity. Quantifying the deviation by a single parameter $Q$, and following the post-Newtonian approximation, we obtain the corresponding deviation in the gravitational potential, shear compon…

Jimmy Buffett's /Math Suks/ is about the equations from general relativity that describe the irresistible attraction that a black hole exercises on the matter in its accretion disk, and the ultimate fate of the latter.
#MisinterpretASong
#HashTagGames

Black-hole formation in binary neutron star mergers: The impact of spin on the prompt-collapse scenario
F. Schianchi, M. Ujevic, A. Neuweiler, H. Gieg, I. Markin, T. Dietrich
https://arxiv.org/abs/2402.16626

Black-hole formation in binary neutron star mergers: The impact of spin on the prompt-collapse scenario
Accurate modeling of the multi-messenger signatures connected to binary neutron star mergers requires proper knowledge on the final remnant's fate and the conditions under which black holes (BHs) can form in such mergers. In this article, we use a suite of 84 numerical-relativity simulations in 28 different physical setups to explore the impact of the individual stars' spin on the merger outcome and on the early postmerger dynamics. We find that for setups close to the prompt-collapse threshold…

This https://arxiv.org/abs/2311.14470 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hepp…

Accessing the gravitational form factors of the nucleon and nuclei through a massive graviton
In contrast to the electromagnetic form factors of the nucleon and nuclei that have been extensively studied in electron scattering, there is no known way to directly measure the gravitational form factors (GFFs), the off-forward hadronic matrix element of the QCD energy-momentum tensor. I suggest exploring the possibility to use massive gravitons in beyond the Standard Model and General Relativity scenarios as a means to access the GFFs of the proton and nuclei at future TeV-scale lepton-ion c…

This https://arxiv.org/abs/2307.12755 has been replaced.
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Testing General Relativity with Black Hole X-Ray Data and ABHModels
The past 10 years have seen tremendous progress in our capability of testing General Relativity in the strong field regime with black hole observations. 10 years ago, the theory of General Relativity was almost completely unexplored in the strong field regime. Today, we have gravitational wave data of the coalescence of stellar-mass black holes, radio images of the supermassive black holes SgrA$^*$ and M87$^*$, and high-quality X-ray data of stellar-mass black holes in X-ray binaries and superm…

This https://arxiv.org/abs/2401.11975 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Crossing the singularity of a gravitational wave collision
A reformulation of general relativity inspired by the Belinski-Khalatnikov-Lifshitz conjecture had been introduced by Ashtekar, Henderson and Sloan which is based on variables closely related to the basic variables of loop quantum gravity, thereby providing a way of classically analyzing singularities that may be carried over to the quantum theory. It is reasonable to expect that these variables are regular at generic spacelike singularities. This has been shown on various examples -- particula…

This https://arxiv.org/abs/2311.07464 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hept…

Consistent first order action functional for gauge theories
A novel first order action principle has been proposed as the possible foundation for a more fundamental theory of General Relativity and the Standard Model. It is shown in this article that the proposal consistently incorporates gravity and matter fields, and guides to a new and robust path towards unification of fundamental interactions.

First investigation of void statistics in numerical relativity simulations
Michael J. Williams, Hayley J. Macpherson, David L. Wiltshire, Chris Stevens
https://arxiv.org/abs/2403.15134

First investigation of void statistics in numerical relativity simulations
We apply and extend standard tools for void statistics to cosmological simulations that solve Einstein's equations with numerical relativity (NR). We obtain a simulated void catalogue without Newtonian approximations, using a new watershed void finder which operates on fluid-based NR simulations produced with the Einstein Toolkit. We compare and contrast measures of void size and void fraction, and compare radial stacked density profiles to empirically-derived Hamaus-Sutter-Wandelt (HSW) densit…

This https://arxiv.org/abs/2403.04069 has been replaced.
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Relational Quantum Mechanics, Quantum Relativism, and the Iteration of Relativity
The idea that the dynamical properties of quantum systems are invariably relative to other systems has recently regained currency. Using Relational Quantum Mechanics (RQM) for a case study, this paper calls attention to a question that has been underappreciated in the debate about quantum relativism: the question of whether relativity iterates. Are there absolute facts about the properties one system possesses relative to a specified reference, or is this again a relative matter, and so on? It …

Gravity induced effective photon mass in the presence of gravity gradient
Igor I. Smolyaninov
https://arxiv.org/abs/2402.15530 https://

Gravity induced effective photon mass in the presence of gravity gradient
Geometry and gravity induced effective photon mass is known to arise in many cases, such as various optical waveguides, Kaluza-Klein theories, and many other optical and general relativity situations. Here we study the appearance of effective photon mass in the Newtonian limit due to the presence of gravity gradient in a locally inertial reference frame. The effective photon mass squared appears to be proportional to the local gravity gradient, and it becomes tachyonic around unstable equilibri…

This https://arxiv.org/abs/2312.02507 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Post-Newtonian Binary Dynamics in Effective Field Theory of Horndeski Gravity
General relativity has been very successful since its proposal more a century ago. However, various cosmological observations and theoretical consistency still motivate us to explore extended gravity theories. Horndeski gravity stands out as one attractive theory by introducing only one scalar field. Here we formulate the post-Newtonian effective field theory of Horndeski gravity and investigate the conservative dynamics of the inspiral compact binary systems. We calculate the leading effective…

This https://arxiv.org/abs/2312.16021 has been replaced.
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Conformal Transformations and Cosmological Perturbations in New General Relativity
We study conformal transformations in the most general parity-preserving models of the New General Relativity type. Then we apply them to analysis of cosmological perturbations in the (simplest) spatially flat cosmologies. Strong coupling issues around Minkowski spacetime are seen for many special cases of these models. At the same time, the behaviour of the most general three-parameter case seems to be very robust, presumably always with only the eight first-class constraints coming from diffe…

Parity violation in the observed galaxy trispectrum
Pritha Paul, Chris Clarkson, Roy Maartens
https://arxiv.org/abs/2402.16478 https://

Parity violation in the observed galaxy trispectrum
Recent measurements of the 4-point correlation function in large-scale galaxy surveys have found apparent evidence of parity violation in the distribution of galaxies. This cannot happen via dynamical gravitational effects in general relativity. If such a violation arose from physics in the early Universe it could indicate important new physics beyond the standard model, and would be at odds with most models of inflation. It is therefore now timely to consider the galaxy trispectrum in more det…

This https://arxiv.org/abs/2401.00339 has been replaced.
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Cylindrical Gravitational Waves in Einstein-Aether Theory
Along the lines of the Einstein-Rosen wave equation of General Relativity (GR), we derive a gravitational wave equation with cylindrical symmetry in the Einstein-aether (EA) theory. We show that the gravitational wave in the EA is periodic in time for both the metric functions $Ψ(r,t)$ and $H(r,t)$. However, in GR, $Ψ(r,t)$ is periodic in time, but $H(r,t)$ is semi-periodic in time, having a secular drifting in the wave frequency. The evolution of wave pulses of a given width is entirely diff…

This https://arxiv.org/abs/2311.13644 has been replaced.
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Towards a measurement theory in QFT: "Impossible" quantum measurements are possible but not ideal
Naive attempts to put together relativity and quantum measurements lead to signaling between space-like separated regions. In QFT, these are known as impossible measurements. We show that the same problem arises in non-relativistic quantum physics, where joint nonlocal measurements (i.e., between systems kept spatially separated) in general lead to signaling, while one would expect no-signaling (based for instance on the principle of no-nonphysical communication). This raises the question: Whic…

This https://arxiv.org/abs/2307.01555 has been replaced.
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A comparative study of MOND and MOG theories versus the$κ$-model: An application to galaxy clusters
Many models have been proposed to minimize the dark matter (DM) content in various astronomical objects at every scale in the Universe. The most widely known model isMOdified Newtonian Dynamics (MOND). MOND was first published by Mordehai Milgromin 1983 (Milgrom, 1983; 2015; see also Banik and Zhao, 2022 for a review). A second concurrent model is modified gravity (MOG), which is a covariant scalar-tensor-vector (STVG)extension of general relativity (Moffat, 2006; 2020). Other theories also exi…

Neutron Stars Mass-Radius relations analysis in the Quintessence scenario
A. Campitelli, L. Mastrototaro
https://arxiv.org/abs/2403.18752 https://

Neutron Stars Mass-Radius relations analysis in the Quintessence scenario
In this paper, we explore the effects of General Relativity modification on the Mass-Radius relations of Neutron Stars induced by the presence of the Quintessence field. We consider, in particular, the Kiselev model, according to which the Quintessence field, being present in the entire Universe, might also be present around massive objects. Considering the Equation of State (EoS) for Baryonic matter BSk22 derived by A. Y. Potekhin et al., we infer the upper limit for NS masses in the presence …

that's not how relativity works #monsterdon

This https://arxiv.org/abs/2311.01424 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

The Hamiltonian constraint in the symmetric teleparallel equivalent of general relativity
General relativity (GR) admits two alternative formulations with the same dynamics attributing the gravitational phenomena to torsion or nonmetricity of the manifold's connection. They lead, respectively, to the teleparallel equivalent of general relativity (TEGR) and the symmetric teleparallel equivalent of general relativity (STEGR). In this work, we focus on STEGR and present its differences with the conventional, curvature-based GR. We exhibit the 3+1 decomposition of the STEGR Lagrangian i…

Hidden Zeros in Scaffolded General Relativity and Exceptional Field Theories
Yang Li, Diederik Roest, Tonnis ter Veldhuis
https://arxiv.org/abs/2403.12939 …

Hidden Zeros in Scaffolded General Relativity and Exceptional Field Theories
It was recently discovered by Arkani-Hamed et al that the colour-ordered scattering amplitudes of Tr$(Φ^3)$, the NLSM and scaffolded YM vanish at specific loci. We build on this observation and demonstrate that, beyond colour ordering, scattering amplitudes can display multiple instances of these hidden zeros. A first example are the flavour-ordered amplitudes of scaffolded General Relativity, corresponding to graviton exchange. The other two cases are multi-flavour DBI and the special Galileo…

This https://arxiv.org/abs/2401.03474 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Nontensorial gravitational wave polarizations from the tensorial degrees of freedom: I. Linearized Lorentz-violating theory of gravity with s tensor
General relativity predicts the existence of only two tensorial gravitational wave polarizations, while a generic metric theories of gravity can possess up to four additional polarizations, including two vector and two scalar ones. These vector/scalar polarizations are in general generated by the intrinsic new vector/scalar degrees of freedom of the specific theories of gravity. In this paper, we show that, with the violation of the Lorentz symmetry in the framework of the standard model extens…

Three dimensional end-to-end simulation for kilonova emission from a black-hole neutron-star merger
Kyohei Kawaguchi, Nanae Domoto, Sho Fujibayashi, Kota Hayashi, Hamid Hamidani, Masaru Shibata, Masaomi Tanaka, Shinya Wanajo
https://arxiv.org/abs/2404.15027

Three dimensional end-to-end simulation for kilonova emission from a black-hole neutron-star merger
We study long-term evolution of the matter ejected in a black-hole neutron-star (BH-NS) merger employing the results of a long-term numerical-relativity simulation and nucleosynthesis calculation, in which both dynamical and post-merger ejecta formation are consistently followed. In particular, we employ the results for the merger of a $1.35\,M_\odot$ NS and a $5.4\,M_\odot$ BH with the dimensionless spin of 0.75. We confirm the finding in the previous studies that thermal pressure induced by r…

This is by Christopher Hoggins. It's an illustration from his book "Roof-less" about his experience of being suddenly made homeless. More details on his blog here: https://christopherhogginsartist.wordpress.com/

This https://arxiv.org/abs/2212.13107 has been replaced.
link: https://scholar.google.com/scholar?q=a

Study on data analysis for Ives-Stilwell-type experiments
Ives-Stilwell experiment in 1938 was a historic experiment for confirming Einstein's special relativity, and various modern types have been repeated by use of laser technology. In this paper, we reveal and solve a long-lasting unrecognized fundamental issue that the data analysis for all those experiments was not consistent with Einstein's definition of the relativistic Doppler effect so that the Doppler effect was not actually confirmed. Based on existing data, we propose a justified data anal…

This https://arxiv.org/abs/2312.12498 has been replaced.
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Testing Graviton Parity and Gaussianity with Planck T-, E- and B-mode Bispectra
Many inflationary theories predict a non-Gaussian spectrum of primordial tensor perturbations, sourced from non-standard vacuum fluctuations, modified general relativity or new particles such as gauge fields. Several such models also predict a chiral spectrum in which one polarization state dominates. In this work, we place constraints on the non-Gaussianity and parity properties of primordial gravitational waves utilizing the Planck PR4 temperature and polarization dataset. Using recently deve…

This https://arxiv.org/abs/2307.09338 has been replaced.
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What is a reference frame in General Relativity?
In General Relativity, reference frames must be distinguished from coordinates. The former represent physical systems interacting with the gravitational system, aside from possible approximations, while the latter are mathematical artefacts. We propose a novel three-fold distinction between Idealised Reference Frames, Dynamical Reference Frames and Real Reference Frames. In doing so, the paper not only clarifies the physical significance of reference frames, but also sheds light on the similari…

An intrinsic connection of space-time points
Ty Shedleski, Muhammad Usman
https://arxiv.org/abs/2403.15508 https://arxiv.org/pdf/2403…

An intrinsic connection of space-time points
Quantum field theory (QFT) describes the dynamics of quantum particles in the quantum realm in the Minkowski space-time, whereas the General Relativity (GR) is a classical theory describing the nature of dynamical behavior of large bodies in different space-times. This research is a proposal to the proof of concept that through the Einstein-Rosen bridge (also known as wormhole) the information can travel between two points %through quantum mechanical phenomenon, Hawking radiation thus proving t…

This https://arxiv.org/abs/2404.11913 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

General Relativity from Intersection Theory
This paper combines the post-Minkowskian expansion of general relativity with the language of intersection theory. Due to the nature of the soft limit inherent to the post-Minkowskian expansion, the intersection-based approach is of enhanced utility in that theory compared to a generic QFT. In the language of intersection theory, Feynman integrals are rephrased in terms of twisted cocycles. The intersection number is a pairing between two such cocycles and its existence allows for the direct pr…

This https://arxiv.org/abs/2307.14256 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Lorentz invariance violation from GRB221009A
The Large High Altitude Air Shower Observatory~(LHAASO) reported observation of photons with energies above 10~TeV from gamma-ray burst GRB 221009A. A suggestion was proposed that this result may contradict our knowledge of special relativity~(SR) and the standard model~(SM), according to which photons of about 10~TeV from such a distant object should be severely suppressed because of the absorption by extragalactic background light. As a result, a number of mechanisms have been proposed to sol…

New measurements of $E_G$: Testing General Relativity with the Weyl potential and galaxy velocities
Nastassia Grimm, Camille Bonvin, Isaac Tutusaus
https://arxiv.org/abs/2403.13709

New measurements of $E_G$: Testing General Relativity with the Weyl potential and galaxy velocities
We combine measurements of galaxy velocities from galaxy surveys with measurements of the Weyl potential from the Dark Energy Survey to test the consistency of General Relativity at cosmological scales. Taking the ratio of two model-independent observables - the growth rate of structure and the Weyl potential - we obtain new measurements of the $E_G$ statistic with precision of $5.8-10.7\%$ at four different redshifts. These measurements provide a considerable improvement to past measurements o…

This https://arxiv.org/abs/2308.01728 has been replaced.
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A new 2D formulation of modified General Relativity
It is well known that the Einstein-Hilbert action in two dimensions is topological and yields an identically vanishing Einstein tensor. Consequently one is faced with difficulties when formulating a non-trivial gravity model. We present a new, intrinsically two-dimensional, approach to this problem based on the Einstein action. This yields a well defined variational approach which results in new field equations that break diffeomorphism invariance. Our proposed approach does not require the int…

[2024-02-26 Mon (UTC), 18 new articles found for gr-qc General Relativity and Quantum Cosmology]

Tensor gauge fields and dark matter in general relativity with fermions
Kevin Cahill
https://arxiv.org/abs/2404.05766 https://arxiv.o…

Tensor gauge fields and dark matter in general relativity with fermions
The action of general relativity with fermions has two independent symmetries: general coordinate invariance and local Lorentz invariance. General coordinate transformations act on coordinates and tensor indices, while local Lorentz transformations act on Dirac and Lorentz indices, much like a noncompact internal symmetry. \par The internal-symmetry character of local Lorentz invariance suggests that it might be implemented by tensor gauge fields with their own Yang-Mills action rather than by …

This https://arxiv.org/abs/2401.00703 has been replaced.
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Exploring Ladder Symmetry and Love Numbers for Static and Rotating Black Holes
Black hole solutions of general relativity exhibit a symmetry for the static perturbations around these spacetimes, known as "ladder symmetry". This symmetry proves useful in constructing a tower of solutions for perturbations and elucidating their general properties. Specifically, the presence of this symmetry leads to vanishing of the tidal love number associated with black holes. In this work, we find the most general spherical symmetric and static black hole spacetime that accommodates this…

Michelson-Morley Experiments: at the crossroads of Relativity, Cosmology and Quantum Physics
Maurizio Consoli, Alessandro Pluchino
https://arxiv.org/abs/2402.12421

Michelson-Morley Experiments: at the crossroads of Relativity, Cosmology and Quantum Physics
Quantum nonlocality would naturally fit into a version of relativity with a preferred reference system. However, acceptance of this idea has traditionally required experimental evidence. Namely, detecting in laboratory a small angular dependence of the velocity of light correlated to the cosmic motion of the Earth. Here, we summarize a new theoretical framework where the tiny, irregular residuals observed so far, from Michelson-Morley to current experiments of laser interferometry, can indeed b…

Kasner Eons
Pablo Bueno, Pablo A. Cano, Robie A. Hennigar
https://arxiv.org/abs/2402.14912 https://arxiv.org/pdf/2402.14912

Kasner Eons
As shown in the classic work of Belinski, Khalatnikov and Lifshitz, the approach to a generic space-like singularity in general relativity consists of a sequence of eras and epochs in which the metric is locally Kasner, connected by brief transitions. When quantum gravity effects are included, we argue that a new type of transition arises, giving rise to Kasner eons: periods which are dominated by emergent physics at each energy scale. We comment on the different ways in which the Einsteinian e…

This https://arxiv.org/abs/2210.07299 has been replaced.
link: https://scholar.google.com/scholar?q=a

Deep learning waveform anomaly detector for numerical relativity catalogs
Numerical Relativity has been of fundamental importance for studying compact binary coalescence dynamics, waveform modelling, and eventually for gravitational waves observations. As the sensitivity of the detector network improves, more precise template modelling will be necessary to guarantee a more accurate estimation of astrophysical parameters. To help improve the accuracy of numerical relativity catalogs, we developed a deep learning model capable of detecting anomalous waveforms. We analy…

Elements formation in radiation-hydrodynamics simulations of kilonovae
Fabio Magistrelli, Sebastiano Bernuzzi, Albino Perego, David Radice
https://arxiv.org/abs/2403.13883

Elements formation in radiation-hydrodynamics simulations of kilonovae
Understanding the details of $r$-process nucleosynthesis in binary neutron star mergers (BNSMs) ejecta is key to interpret kilonovae observations and to identify the role of BNSMs in the origin of heavy elements. We present a self-consistent 2-dimensional (ray-by-ray) radiation-hydrodynamic evolution of BNSM ejecta with an online nuclear network (NN) up to the days timescale. For the first time, an initial numerical-relativity ejecta profile composed of the dynamical component, spiral-wave and …

This https://arxiv.org/abs/2312.05438 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Adaptive mesh refinement in binary black holes simulations
We discuss refinement criteria for the Berger-Rigoutsos (block-based) refinement algorithm in our numerical relativity code GR-Athena++ in the context of binary black hole merger simulations. We compare three different strategies: the "box-in-box" approach, the "sphere-in-sphere" approach and a local criterion for refinement based on the estimation of truncation error of the finite difference scheme. We extract and compare gravitational waveforms using the three different mesh refinement method…

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…

Probing black hole `charge' from the binary black hole inspiral
N. V. Krishnendu, Sumanta Chakraborty
https://arxiv.org/abs/2402.15336 https://<…

Probing black hole `charge' from the binary black hole inspiral
Recent gravitational wave (GW) observations have enabled us to look beyond the standard paradigm of gravitational physics, namely general relativity (GR). Along with the mass and the angular momentum, which typical astrophysical black holes (BHs) are endowed with, theories beyond GR generically induce `charge' to these BHs. Notably, for BHs carrying the extra `charge' hair, we expect the BH absorption effects to modify accordingly and alter the tidal heating terms. Hence, the inclusion of the c…

This https://arxiv.org/abs/2312.08811 has been replaced.
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Theoretically motivated dark electromagnetism as the origin of relativistic MOND
The present paper is a modest attempt to initiate the research program outlined in this abstract. We propose that general relativity and relativistic MOND (RelMOND) are analogues of the broken electroweak symmetry. That is, $SU(2)_R \times U(1)_{YDEM} \rightarrow U(1)_{DEM}$ (DEM stands for dark electromagnetism), and GR is assumed to arise from the broken $SU(2)_R$ symmetry, and is analogous to the weak force. RelMOND is identified with dark electromagnetism $U(1)_{DEM}$, which is the remainin…

A study of the Inspiral-Merger-Ringdown Consistency Test with gravitational-wave signals from compact binaries in eccentric orbits
Md Arif Shaikh, Sajad A. Bhat, Shasvath J. Kapadia
https://arxiv.org/abs/2402.15110

A study of the Inspiral-Merger-Ringdown Consistency Test with gravitational-wave signals from compact binaries in eccentric orbits
The Inspiral Merger Ringdown Consistency Test (IMRCT) is one among a battery of tests of general relativity (GR) employed by the LIGO-Virgo-KAGRA (LVK) collaboration. It is used to search for deviations from GR in detected gravitational waves (GWs) from compact binary coalescences (CBCs) in a model-agnostic way. The test compares source parameter estimates extracted independently from the inspiral and post-inspiral portions of the CBC signals and, therefore, crucially relies on the accurate mod…

This https://arxiv.org/abs/2312.07794 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hept…

Observational Tests of 4D Double Field Theory
Although General Relativity (GR) is a very successful theory of gravity, it cannot explain every observational phenomenon. People have tried many kinds of modified gravity theory to explain these phenomena which GR cannot explain very well, such as string theory. In recent years Double Field Theory (DFT) has been an exciting research area in string theory. The most general, spherically symmetric, asymptotically flat, static vacuum solution to D = 4 double field theory has been derived by S.M. K…

Numerical relativity simulations of black hole and relativistic jet formation
Takami Kuroda, Masaru Shibata
https://arxiv.org/abs/2404.02792 https://

Numerical relativity simulations of black hole and relativistic jet formation
We investigate impacts of stellar rotation and magnetic fields on black hole (BH) formation and its subsequent explosive activities, by conducting axisymmetric radiation-magnetohydrodynamics simulations of gravitational collapse of a 70 $M_\odot$ star with two-moment multi energy neutrino transport in numerical relativity. Due to its dense stellar structure, all models cannot avoid the eventual BH formation even though a strongly magnetized model experiences the so-called magnetorotational expl…

Perturbations of bimetric gravity on most general spherically symmetric spacetimes
David Brizuela, Marco de Cesare, Araceli Soler Oficial
https://arxiv.org/abs/2402.15327

Perturbations of bimetric gravity on most general spherically symmetric spacetimes
We present a formalism to study linear perturbations of bimetric gravity on any spherically symmetric background, including dynamical spacetimes. The setup is based on the Gerlach-Sengupta formalism for general relativity. Each of the two background metrics is written as a warped product between a two-dimensional Lorentzian metric and the round metric of the two-sphere. The different perturbations are then decomposed in terms of tensor spherical harmonics, which makes the two polarity (axial an…

Towards testing the general bounce cosmology with the CMB B-mode auto-bispectrum
Shingo Akama, Giorgio Orlando, Paola C. M. Delgado
https://arxiv.org/abs/2404.14393

Towards testing the general bounce cosmology with the CMB B-mode auto-bispectrum
It has been shown that a three-point correlation function of tensor perturbations from a bounce model in general relativity with a minimally-coupled scalar field is highly suppressed, and the resultant three-point function of cosmic microwave background (CMB) B-mode polarizations is too small to be detected by CMB experiments. On the other hand, bounce models in a more general class with a non-minimal derivative coupling between a scalar field and gravity can predict the three-point correlation…

Numerical Relativity Multimodal Waveforms using Absorbing Boundary Conditions
Luisa T. Buchman, Matthew D. Duez, Marlo Morales, Mark A. Scheel, Tim M. Kostersitz, Andrew M. Evans
https://arxiv.org/abs/2402.12544

Numerical Relativity Multimodal Waveforms using Absorbing Boundary Conditions
Errors due to imperfect boundary conditions in numerical relativity simulations of binary black holes can produce unphysical reflections of gravitational waves which compromise the accuracy of waveform predictions, especially for subdominant modes. A system of higher order absorbing boundary conditions which greatly reduces this problem was introduced in earlier work [arXiv:gr-qc/0608051]. In this paper, we devise two new implementations of this boundary condition system in the Spectral Einstei…

Quantum Spacetimes from General Relativity?
Albert Much
https://arxiv.org/abs/2404.13029 https://arxiv.org/pdf/2404.13029

Quantum Spacetimes from General Relativity?
We introduce a non-commutative product for curved spacetimes, that can be regarded as a generalization of the Rieffel (or Moyal-Weyl) product. This product employs the exponential map and a Poisson tensor, and the deformed product maintains associativity under the condition that the Poisson tensor $Θ$ satisfies $Θ^{μν}\nabla_νΘ^{ρσ}=0$, in relation to a Levi-Cevita connection. We proceed to solve the associativity condition for various physical spacetimes, uncovering non-commutative str…

General Relativity from Intersection Theory
Hjalte Frellesvig, Toni Teschke
https://arxiv.org/abs/2404.11913 https://arxiv.org/pdf/24…

General Relativity from Intersection Theory
This paper combines the post-Minkowskian expansion of general relativity with the language of intersection theory. Due to the nature of the soft limit inherent to the post-Minkowskian expansion, the intersection-based approach is of enhanced utility in that theory compared to a generic QFT. In the language of intersection theory, Feynman integrals are rephrased in terms of twisted cocycles. The intersection number is a pairing between two such cocycles and its existence allows for the direct pr…

This https://arxiv.org/abs/2404.02783 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Simulating the Universe from the cosmological horizon to halo scales
Ultra-large scales close to the cosmological horizon will be probed by the upcoming observational campaigns. They hold the promise to constrain single-field inflation as well as general relativity, but in order to include them in the forthcoming analyses, their modelling has to be robust. In particular, general relativistic effects may be mistaken for primordial signals, and no consensus has emerged either from analytical modelling nor from the numerical route, obstructed by the large dynamical…

[2024-03-25 Mon (UTC), 8 new articles found for gr-qc General Relativity and Quantum Cosmology]

This https://arxiv.org/abs/2310.01249 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Probing nontensorial gravitational waves with a next-generation ground-based detector network
In General Relativity, there are only two polarizations for gravitational waves. However, up to six polarizations are possible in a generic metric theory of gravity. Therefore, measuring the polarization content of gravitational waves provides an efficient way to test theories of gravity. We analyze the sensitivity of a next-generation ground-based detector network to nontensorial polarizations. We present our method to localize GW signals in the time-frequency domain and construct the model-in…

This https://arxiv.org/abs/2311.11311 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Actively Learning Numerical Relativity
Data analysis of gravitational waves detected by the Ligo-Virgo-Kagra collaboration and future observatories relies on precise modelling of the sources. In order to build, calibrate and validate current models, we resort to expensive simulations in Numerical Relativity (NR), the fully-fledged simulation of Einstein's Equations. Since simulation costs and the dimensionality of parameter space are prohibitive to perform a dense coverage, approximate models interpolate among the available simulati…

Primordial black hole formation processes with full numerical relativity
Eloy de Jong
https://arxiv.org/abs/2403.02878 https://arxiv.…

Primordial black hole formation processes with full numerical relativity
See thesis for complete abstract. Primordial black holes (PBHs) can form in the early universe, and there are several mass windows in which their abundance today may be large enough to comprise a significant part of the dark matter density. Additionally, numerical relativity (NR) allows one to investigate the formation processes of PBHs in the fully nonlinear strong-gravity regime. In this thesis, we will describe the use of NR methods to study PBH formation, motivated in particular by open q…

This https://arxiv.org/abs/2307.12096 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

The Interiors of Singularity-Free Rotating Black Holes
General Relativity provides us with some solutions for rotating black holes. However, there are some problems associated with them: the appearance of singularities, the possibility of violations of the cosmic censorship conjecture, the existence of regions where the mass acts repulsively and the violation of causality. Many authors consider that these problems reveal the existence of certain limits in the applicability of General Relativity. For instance, it is believed that the same existence …

Optimizing post-Newtonian parameters and fixing the BMS frame for numerical-relativity waveform hybridizations
Dongze Sun, Michael Boyle, Keefe Mitman, Mark A. Scheel, Leo C. Stein, Saul A. Teukolsky, Vijay Varma
https://arxiv.org/abs/2403.10278

Optimizing post-Newtonian parameters and fixing the BMS frame for numerical-relativity waveform hybridizations
Numerical relativity (NR) simulations of binary black holes provide precise waveforms, but are typically too computationally expensive to produce waveforms with enough orbits to cover the whole frequency band of gravitational-wave observatories. Accordingly, it is important to be able to hybridize NR waveforms with analytic, post-Newtonian (PN) waveforms, which are accurate during the early inspiral phase. We show that to build such hybrids, it is crucial to both fix the Bondi-Metzner-Sachs (BM…

Optimizing post-Newtonian parameters and fixing the BMS frame for numerical-relativity waveform hybridizations
Dongze Sun, Michael Boyle, Keefe Mitman, Mark A. Scheel, Leo C. Stein, Saul A. Teukolsky, Vijay Varma
https://arxiv.org/abs/2403.10278

Optimizing post-Newtonian parameters and fixing the BMS frame for numerical-relativity waveform hybridizations
Numerical relativity (NR) simulations of binary black holes provide precise waveforms, but are typically too computationally expensive to produce waveforms with enough orbits to cover the whole frequency band of gravitational-wave observatories. Accordingly, it is important to be able to hybridize NR waveforms with analytic, post-Newtonian (PN) waveforms, which are accurate during the early inspiral phase. We show that to build such hybrids, it is crucial to both fix the Bondi-Metzner-Sachs (BM…

This https://arxiv.org/abs/2310.18962 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

About the ability of agnostic X-ray tests of the Kerr Hypothesis to discover new physics
In the past decade, we have seen an unprecedented progress in our ability of testing general relativity in the strong field regime with black hole observations. Most studies have focused on the so-called tests of the Kerr hypothesis: they have tried to verify whether the spacetime geometry around black holes is described by the Kerr solution as expected in general relativity. One can follow either a theory-specific analysis or an agnostic approach. Each strategy has its advantages and disadvant…

Loop Special Relativity: Kaluza-Klein area metric as a line element for stringy events
Aharon Davidson, Nadav Barkai
https://arxiv.org/abs/2403.11800 https…

Loop Special Relativity: Kaluza-Klein area metric as a line element for stringy events
Let a physical event constitute a simple loop in spacetime. This in turn calls for a generalized loop line element (= distance$^2$ between two neighboring loops) capable of restoring, at the shrinking loop limit, the special relativistic line element (= distance$^2$ between the two neighboring center-of-masses, respectively). Sticking at first stage to a flat Euclidean/Minkowski background, one is led to such a preliminary loop line element, where the role of coordinates is played by the orient…

Approximations of the quasi-local Bartnik mass in general relativity
Leon Escobar-Diaz, Chris Stevens
https://arxiv.org/abs/2403.11372 https://

Approximations of the quasi-local Bartnik mass in general relativity
In this study, we employ eth-operators and spin-weighted spherical harmonics to express the ADM mass of a static space-time based on the mean values of its components over a a radius-$r$ sphere. While initially derived for standard spherical coordinates, we showcase its adaptability by demonstrating its usefulness in expressing a quasilocal mass; specifically, the Bartnik mass, of an almost round 2D-hypersurface in terms of some specific boundary conditions. Additionally, we utilize this formul…

This https://arxiv.org/abs/2312.12947 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Euclidean self-dual gravity: Ashtekar variables without gauge fixing
The Gotay-Nester-Hinds method is used in this paper to study the Hamiltonian formulation of the Euclidean self-dual action. This action can be used to arrive at the complex Ashtekar formulation of General Relativity or a real connection formulation for Euclidean General Relativity. The main result of the paper is a derivation of the Ashtekar formulation for Euclidean gravity without using any gauge fixing. It is interesting to compare this derivation with the one corresponding to the Holst acti…

[2024-02-23 Fri (UTC), 10 new articles found for gr-qc General Relativity and Quantum Cosmology]

This https://arxiv.org/abs/2212.05536 has been replaced.
link: https://scholar.google.com/scholar?q=a

Local Limit of Nonlocal Gravity: A Teleparallel Extension of General Relativity
We describe a general constitutive framework for a teleparallel extension of the general theory of relativity. This approach goes beyond the teleparallel equivalent of general relativity (TEGR) by broadening the analogy with the electrodynamics of media. In particular, the main purpose of this paper is to investigate in detail a local constitutive extension of TEGR that is the local limit of nonlocal gravity (NLG). Within this framework, we study the modified FLRW cosmological models. Of these,…

[2024-04-22 Mon (UTC), 7 new articles found for gr-qc General Relativity and Quantum Cosmology]

This https://arxiv.org/abs/2308.07232 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Lyapunov Exponents to Test General Relativity
Photon rings are key targets for near-future space-based very-long baseline interferometry missions. The ratio of flux measured between successive light-rings is characterized by the Lyapunov exponents of the corresponding nearly-bound null geodesics. Therefore, understanding Lyapunov exponents in this environment is of crucial importance to understanding black hole observations in general, and in particular, they may offer a route for constraining modified theories of gravity. While recent wor…

A robust test of general relativity at the galactic scales by combining strong lensing systems and gravitational wave standard sirens
Tonghua Liu, Marek Biesiada, Shuxun Tian, Kai Liao
https://arxiv.org/abs/2404.05907

A robust test of general relativity at the galactic scales by combining strong lensing systems and gravitational wave standard sirens
The measurement of the parametrized post-Newtonian parameter $γ_{\rm{PPN}}$ is a robust test of general relativity (GR). In some modified theories of gravity, $γ_{\rm{PPN}}$ may evolve with the redshift and deviate from one at high redshifts. This means that precise constraints on $γ_{\rm{PPN}}$ acquired in the solar system experiments could not be sufficient to test such theories and it is necessary to constrain $γ_{\rm{PPN}}$with high precision at high redshifts. However, in many approach…

The impact of anisotropic sky-sampling on the Hubble constant in numerical relativity
Hayley J. Macpherson
https://arxiv.org/abs/2402.09659 https://…

The impact of anisotropic sky-sampling on the Hubble constant in numerical relativity
We study the impact of nearby inhomogeneities on an observer's inference of the Hubble constant. Large-scale structures induce a dependence of cosmological parameters on observer position as well as an anisotropic variance of those parameters across an observer's sky. While the former has been explored quite thoroughly, the latter has not. Incomplete sampling of an anisotropic sky could introduce a bias in our cosmological inference if we assume an isotropic expansion law. In this work, we use …

This https://arxiv.org/abs/2307.16534 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Single-rotating Five-dimensional Near-horizon Extremal Geometry in General Relativity
The geometries with SL$(2,\mathbb{R})$ and some axial U$(1)$ isometries are called ``near-horizon extremal geometries" and are found usually, but not necessarily, in the near-horizon limit of the extremal black holes. We present a new member of this family of solutions in five-dimensional Einstein-Hilbert gravity that has only one nonzero angular momentum. In contrast with the single-rotating Myers-Perry extremal black hole and its near-horizon geometry in five dimensions, this solution may hav…

This https://arxiv.org/abs/2404.09374 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Classical double copy in the black hole mini-superspace
We give a novel formulation of classical double copy in the mini-superspace of static, spherically symmetric black holes where the map between the solutions of general relativity and Maxwell's theory can be realized in Boyer-Lindsquit coordinates. By employing the reduced action principle, we show that the double copy structure can be generalized to Lovelock gravities and quasi-topological gravities. However, the gravitational solutions are mapped to the purely electric solutions of Maxwell's t…

This https://arxiv.org/abs/2307.06629 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

A well-balanced discontinuous Galerkin method for the first--order Z4 formulation of the Einstein--Euler system
In this paper we develop a new well-balanced discontinuous Galerkin (DG) finite element scheme with subcell finite volume (FV) limiter for the numerical solution of the Einstein--Euler equations of general relativity based on a first order hyperbolic reformulation of the Z4 formalism. The first order Z4 system, which is composed of 59 equations, is analyzed and proven to be strongly hyperbolic for a general metric. The well-balancing is achieved for arbitrary but a priori known equilibria by su…

This https://arxiv.org/abs/2403.19608 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Classical Kerr-Schild double copy in bigravity for maximally symmetric spacetimes
A generalized Kerr-Schild ansatz for bigravity, already considered in the literature, which leads to linear interactions between the metrics is used to study the bigravity equations in the context of the double copy. By contracting the resulting spin-2 field bigravity equations of motion using Killing vector fields, as is usually carried out in general relativity, we arrive to the single and zeroth copy equations for the mentioned ansatz. For the case of stationary solutions, we obtain two Maxw…

[2024-02-21 Wed (UTC), 10 new articles found for gr-qc General Relativity and Quantum Cosmology]

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…

Angular momentum sensitivities in scalar-tensor theories
Adrien Kuntz, Enrico Barausse
https://arxiv.org/abs/2403.07980 https://arxiv…

Angular momentum sensitivities in scalar-tensor theories
Scalar-tensor theories have a long history as possible phenomenological alternatives to General Relativity, but are known to potentially produce deviations from the (strong) equivalence principle in systems involving self-gravitating objects, as a result of the presence of an additional gravitational scalar field besides the tensor modes of General Relativity. We describe here a novel mechanism whereby the equivalence principle is violated for an isolated rotating neutron star, if the gravitati…

This https://arxiv.org/abs/2203.04824 has been replaced.
link: https://scholar.google.com/scholar?q=a

De Sitter-invariant approach to cosmology
The spacetime short-distance structure at the Planck scale is governed by the Planck length, usually interpreted as a three-dimensional Euclidian length. As such, it is not Lorentz invariant and clashes with Einstein's special relativity, which is thus unable to describe the Planck scale kinematics. The solution to this problem is twofold. First, one has to re-interpret the Planck length as a Lorentz invariant four-dimensional pseudo-length. Second, to comply with a non-vanishing cosmological t…

This https://arxiv.org/abs/2311.17999 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Spherically symmetric vacuum solutions in 1-Parameter New General Relativity and their phenomenology
In this work, we study spherically symmetric vacuum solutions in 1-parameter New General Relativity (NGR), a specific theory in teleparallel gravity which is constructed from the three possible quadratic scalars obtained from torsion with arbitrary coefficients satisfying the requirements for the absence of ghosts. In this class of modified theories of gravity, the observable effects of gravity result from the torsion rather than the curvature of the spacetime. Unlike in GR, where the fundament…

This https://arxiv.org/abs/2312.01145 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Reconstruction the scalar-torsion gravity version from the frame of exact cosmological solutions
We consider the cosmological models based on the scalar-torsion gravity implying non-minimal coupling between torsion and the scalar field as modification of teleparallel equivalent of general relativity. Based on generalized exact solutions of the equations of cosmological dynamics, the type of scalar-torsion gravity was reconstructed. Also, based on observational constraints on the values of the parameters of cosmological perturbations, the type of the coupling function was determined. It was…

Scalarization of isolated black holes in scalar Gauss-Bonnet theory in the fixing-the-equations approach
Guillermo Lara, Harald P. Pfeiffer, Nikolas A. Wittek, Nils L. Vu, Kyle C. Nelli, Alexander Carpenter, Geoffrey Lovelace, Mark A. Scheel, William Throwe
https://arxiv.org/abs/2403.08705…

Scalarization of isolated black holes in scalar Gauss-Bonnet theory in the fixing-the-equations approach
One of the most promising avenues to perform numerical evolutions in theories beyond General Relativity is the fixing-the-equations approach, a proposal in which new ``driver'' equations are added to the evolution equations in a way that allows for stable numerical evolutions. In this direction, we extend the numerical relativity code SpECTRE to evolve a ``fixed'' version of scalar Gauss-Bonnet theory in the decoupling limit, a phenomenologically interesting theory that allows for hairy black h…

Testing the Boundary-to-Bound Correspondence with Numerical Relativity
Anuj Kankani, Sean T. McWilliams
https://arxiv.org/abs/2404.03607 https://

Testing the Boundary-to-Bound Correspondence with Numerical Relativity
The Boundary-to-Bound (B2B) correspondence, which connects orbital and radiative observables between bound and unbound orbits, has recently been introduced and demonstrated in the perturbative regime. We produce a large number of numerical relativity simulations of bound and unbound encounters between two nonspinning equal mass black holes in order to test this correspondence in the non-perturbative regime. We focus on testing the radiated energy and angular momentum, as well as orbital paramet…

Testing the Boundary-to-Bound Correspondence with Numerical Relativity
Anuj Kankani, Sean T. McWilliams
https://arxiv.org/abs/2404.03607 https://

Testing the Boundary-to-Bound Correspondence with Numerical Relativity
The Boundary-to-Bound (B2B) correspondence, which connects orbital and radiative observables between bound and unbound orbits, has recently been introduced and demonstrated in the perturbative regime. We produce a large number of numerical relativity simulations of bound and unbound encounters between two nonspinning equal mass black holes in order to test this correspondence in the non-perturbative regime. We focus on testing the radiated energy and angular momentum, as well as orbital paramet…

Modified gravity theories from the Barrow hypothesis
Ankit Anand, Ruben Campos Delgado
https://arxiv.org/abs/2403.13687 https://arxiv…

Modified gravity theories from the Barrow hypothesis
Barrow proposed that quantum gravity effects might introduce fractal corrections to the area of the event horizon of black holes. The area law gets modified as $S \propto A^{1+Δ/2}$, with $0\leqΔ\leq 1$. It was so far unclear whether this assumption could lead to meaningful quantum gravity theories beyond general relativity. In this paper, we argue that this is indeed the case. In particular, assuming $Δ$ to be a radial function, we show that the Barrow hypothesis, together with the Jacobson…

This https://arxiv.org/abs/2312.11351 has been replaced.
link: https://scholar.google.com/scholar?q=a

Disentangling photon rings beyond General Relativity with future radio-telescope arrays
New physics beyond General Relativity can modify image features of black holes and horizonless spacetimes and increase the separation between photon rings. This motivates us to explore synthetic images consisting of two thin rings. Our synthetic images are parameterized by the separation as well as the relative flux density of the two rings. We perform fits to the visibility amplitude and analyze closure quantities. The current Event Horizon Telescope array cannot detect the presence of a secon…

The classical-quantum hybrid canonical dynamics and its difficulties with special and general relativity
Lajos Di\'osi
https://arxiv.org/abs/2404.07723

The classical-quantum hybrid canonical dynamics and its difficulties with special and general relativity
We discuss the Hamiltonian hybrid coupling between a classical and a quantum subsystem. If applicable to classical gravity coupled to quantized matter, this hybrid theory might realize a captivating `postquantum' alternative to full quantum-gravity. We summarize the nonrelativistic hybrid dynamics in improved formalism adequate to Hamiltonian systems. The mandatory decoherence and diffusion terms become divergent in special and general relativistic extensions. It is not yet known if any renorma…

This https://arxiv.org/abs/2311.03656 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

The impact of selection biases on tests of general relativity with gravitational-wave inspirals
Tests of general relativity with gravitational wave observations from merging compact binaries continue to confirm Einstein's theory of gravity with increasing precision. However, these tests have so far only been applied to signals that were first confidently detected by matched-filter searches assuming general relativity templates. This raises the question of selection biases: what is the largest deviation from general relativity that current searches can detect, and are current constraints o…

This https://arxiv.org/abs/2306.11717 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Equivalence of matter-type modified gravity theories to general relativity with nonminimal matter interaction
In this study, we first establish that gravity models incorporating matter-related terms, such as $f(\mathcal{L}_{\rm m})$, $f(g_{μν} T^{μν})$, and $f(T_{μν} T^{μν})$, into the usual matter Lagrangian density $\mathcal{L}_{\rm m}$, are equivalent to general relativity with nonminimal matter interactions. Through the redefinition $\mathcal{L}_{\rm m}+f \rightarrow \mathcal{L}_{\rm m}^{\rm tot}$, these models are exactly GR, yet the usual material field $T_{μν}$ and its accompanying par…

On black bounce spacetimes in non-linear electrodynamics
Geov\'a Alencar, Manuel E. Rodrigues, Diego S\'aez-Chill\'on G\'omez, Marcos V. de S. Silva
https://arxiv.org/abs/2403.12897

On black bounce spacetimes in non-linear electrodynamics
One of the main issues in gravitation is the presence of singularities in the most common spacetime solutions of General Relativity, as the case of black holes. A way of constructing regular solutions that remove space-like singularities consist on implement a bounce on such spacetime, leading what is usually known as black bounce spacetimes. Such spacetimes are known to describe regular black holes or traversable wormholes. However, one of the main issues lies on reconstructing the appropriate…

This https://arxiv.org/abs/2311.05983 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Prospects of detecting deviations to Kerr geometry with radiation reaction effects in EMRIs
Direct detection of gravitational waves and binary black hole mergers have proven to be remarkable investigations of general relativity. In order to have a definitive answer as to whether the black hole spacetime under test is the Kerr or non-Kerr, one requires accurate mapping of the metric. Since EMRIs are perfect candidates for space-based detectors, Laser Interferometer Space Antenna (LISA) observations will serve a crucial purpose in mapping the spacetime metric. In this article, we consid…

This https://arxiv.org/abs/2311.07193 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Membrane Models as a Means of Propulsion in General Relativity: Super-Luminal Warp-Drive that Satisfies the Weak Energy Condition
Presented are toy-models for sub-luminal and super-luminal warp-drives in 3+1 dimensions. The models are constructed in a chimeric manner - as different bulk space-times separated by thin membranes. The membranes contain perfect-fluid-like stress-energy tensors. The Israel junction conditions relate this stress-energy to a jump in extrinsic curvature across the brane, which in turn manifests as apparent acceleration in the bulk space-times. The acceleration on either side of the brane may be se…

This https://arxiv.org/abs/2310.10144 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Cosmology based on entropy
At present, there is practically no doubt that general relativity is closely related to gravity. Moreover, after the work of Jacobson, Padmanabhan and others, it became clear that a thermodynamic interpretation of Einstein's relativistic equations is possible. On the other hand, we are witnessing the conceptual problems of the SCM (the problem of the cosmological constant, the problem of coincidences) and many years of futile attempts to directly fix the main components of the model (dark energ…

On the weak and strong field effects in antiscalar background
Eduard Mychelkin, Maxim Makukov, Gulnara Suliyeva, Nosratollah Jafari
https://arxiv.org/abs/2403.11610

On the weak and strong field effects in antiscalar background
The triumph of general relativity under the banner "gravity is geometry" began with confirming the crucial effects within the Solar system and proceeded recently to the strong-field shadow effect for the compact object in the center of the Milky Way. Here, we examine some of those phenomena for the Einstein-scalar equations in the antiscalar regime to reveal the difference from vacuum both in weak and strong fields. As a result, we find that for week-field perihelion shift the difference betwee…

This https://arxiv.org/abs/2307.08867 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Spectral-infinite element method approach for computing asymptotically flat initial data sets in general relativity
In this work, we introduce a spectral-infinite element method for solving Einstein's constraint equations in hyperbolic form. As an application of this, we use this method for computing asymptotically flat perturbations of a Kerr black hole with small angular momentum. Our numerical infrastructure is based on the use of a spin-weighted spherical harmonic transform combined with an infinite element method for solving partial differential equations in unbounded domains.

Testing gravitational waveforms in full General Relativity
Fabio D'Ambrosio, Francesco Gozzini, Lavinia Heisenberg, Henri Inchausp\'e, David Maibach, Jann Zosso
https://arxiv.org/abs/2402.19397

Testing gravitational waveforms in full General Relativity
We perform a comprehensive analysis of state-of-the-art waveform models, focusing on their predictions concerning kick velocity and inferred gravitational wave memory. In our investigation we assess the accuracy of waveform models using energy-momentum balance laws, which were derived in the framework of full, non-linear General Relativity. The numerical accuracy assessment is performed for precessing as well as non-precessing scenarios for models belonging to the \textit{EOB}, \textit{Phenom},…

Space-time-matter gravity as the origin of rotation in 4-D stationary and axisymmetric vacuum solutions
Jos\'e Luis Hern\'andez-Pastora
https://arxiv.org/abs/2402.10560

Space-time-matter gravity as the origin of rotation in 4-D stationary and axisymmetric vacuum solutions
The standard theory of General Relativity (GR) currently provides the most reliable description of all gravitational events in Astrophysics and Cosmology. However, current Astronomy allows measurements that contradict the predictions of GR in some gravitational scenarios such as the accelerated expansion of the Universe, the fast rotation of cluster of galaxies of the so strongly deflection of light by gravitational lenses. This has led the scientific community to propose modifications of the t…

Does spacetime have memories? Searching for gravitational-wave memory in the third LIGO-Virgo-KAGRA gravitational-wave transient catalogue
Shun Yin Cheung, Paul D. Lasky, Eric Thrane
https://arxiv.org/abs/2404.11919

Does spacetime have memories? Searching for gravitational-wave memory in the third LIGO-Virgo-KAGRA gravitational-wave transient catalogue
Gravitational-wave memory is a non-linear effect predicted by general relativity that remains undetected. We apply a Bayesian analysis framework to search for gravitational-wave memory using binary black hole mergers in LIGO-Virgo-KAGRA's third gravitational-wave transient catalogue. We obtain a Bayes factor of $\ln \text{BF}=0.01$, in favour of the no-memory hypothesis, which implies that we are unable to measure memory with currently available data. This is consistent with previous work, sugg…

This https://arxiv.org/abs/2309.11383 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_grqc_…

Shadows of a generic class of spherically symmetric, static spacetimes
We explore the characteristics of shadows for a general class of spherically symmetric, static spacetimes, which may arise in general relativity or in modified theories of gravity. The chosen line element involves a sum (with constant but different coefficients) of integer powers of $\frac{1}{\text{r}}$ in $\text{g}_\text{tt}$ and $\text{g}_\text{rr}$, in the Schwarzschild gauge. We begin our discussion by motivating the line element through a study of the energy conditions (null and weak) and …

This https://arxiv.org/abs/2402.02534 has been replaced.
link: https://scholar.google.com/scholar?q=a

Black holes and regular black holes in coincident $f(\mathbb{Q},\mathbb{B}_Q)$ gravity coupled to nonlinear electrodynamics
In this work, we consider an extension of the symmetric teleparallel equivalent of General Relativity (STEGR), namely, $f(\mathbb{Q})$ gravity, by including a boundary term $\mathbb{B}_Q$, where $\mathbb{Q}$ is the non-metricity scalar. More specifically, we explore static and spherically symmetric black hole and regular black hole solutions in $f(\mathbb{Q},\mathbb{B}_Q)$ gravity coupled to nonlinear electrodynamics (NLED). In particular, to obtain black hole solutions, and in order to ensure …

[2024-03-18 Mon (UTC), 20 new articles found for gr-qc General Relativity and Quantum Cosmology]