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On supertranslation invariant Lorentz charges Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-15 Sumanta Chakraborty, S. K. Jahanur Hoque, Amitabh Virmani
In recent papers, Fuentealba, Henneaux, and Troessaert (FHT) gave definitions for supertranslation invariant Lorentz charges in the ADM Hamiltonian formalism and showed that their definitions match with the Chen, Wang, Yau (CWY) definitions of Lorentz charges at null infinity which are free from “supertranslation ambiguities”. In this brief note, motivated by the analysis of FHT, we write expressions
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Proca stars in excited states Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-15 Carlos Joaquin, Miguel Alcubierre
In this paper, we consider families of solutions for excited states of Proca stars in spherical symmetry. We focus on the first two excited configurations and perform a series of fully non-linear dynamical simulations in order to study their properties and stability. Our analysis reveals that excited Proca stars are always unstable against even very small perturbations, and their dynamical evolution
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Black holes as laboratories: searching for ultralight fields Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-13 Richard Brito
The interaction of black holes with classical fields can lead to many interesting phenomena such as black-hole superradiance and the superradiant instability. The existence of these effects has been shown to have implications for beyond Standard Model particles that could explain dark matter, namely ultralight bosonic fields. In this note I give a historical account of this topic and briefly go through
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The enigmatic gravitational partition function Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-13 Batoul Banihashemi, Ted Jacobson
The saddle point approximation to formal quantum gravitational partition functions has yielded plausible computations of horizon entropy in various settings, but it stands on shaky ground. In this paper we visit some of that shaky ground, address some foundational questions, and describe efforts toward a more solid footing. We focus on the case of de Sitter horizon entropy which, it has been argued
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Non-static axisymmetric structures embedded in an asymptotically $$\Lambda $$ CDM universe Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-12 Gonzalo García-Reyes
We construct non-static adiabatic axisymmetric structures embedded in an asymptotically \(\Lambda \)CDM universe from given solutions of the Poisson’s equation of Newtonian gravity, using a particular form of the metric in isotropic coordinates. The approach is used in building of a razor-thin disk source made of perfect fluid for the McVittie metric, a system composite by a Plummer-type perfect fluid
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Testing the nature of compact objects and the black hole paradigm Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-08 Mariafelicia De Laurentis, Paolo Pani
Do compact objects other than black holes and neutron stars exist in the universe? Do all black holes conform with the predictions of Einstein’s General Relativity? Do classical black holes exist at all? Future gravitational-wave observations and black-hole imaging might shed light on these foundational questions and deepen our understanding of the dark cosmos.
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Thin shell wormhole from rotating hairy black hole in (2+1)-dimensions Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-08 Farook Rahaman, Nilofar Rahman, Mehedi Kalam, Masum Murshid, Amit Das, Sayeedul Islam, Shyam Das
In this article, we theoretically construct a (2 + 1)-dimensional rotating thin shell wormhole using the Darmois-Israel junction formalism. This thin shell wormhole whose validity has been checked by analyzing the energy conditions, specifically, the weak and null energy conditions, is actually constructed by cutting and pasting two rotating hairy black hole spacetimes in (2+1)-dimensions. We further
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Quintessence scalar field and cosmological constant: dynamics of a multi-component dark energy model Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-07 Prasanta Sahoo, Nandan Roy, Himadri Shekhar Mondal
This study explores the dynamics and phase-space behavior of a multi-component dark energy model, where the dark sector consists of a minimally coupled canonical scalar field and the cosmological constant, using a dynamical system analysis setup for various types of potential for which a general parameterization of the scalar field potentials has been considered. Several fixed points with different
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Thermodynamic phase transition of Anti-de Sitter Reissner–Nordström black holes with exotic Einstein–Maxwell gravities Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-06 Hossein Ghaffarnejad, Elham Ghasemi
To consider the inevitable cosmic magnetic effects instead of the unknown dark sector of matter/energy on the inflation phase of the expanding universe some authors have proposed several extended exotic Einstein–Maxwell gravities which are addressed in this work. Some of these exotic models include directional interaction terms between the electromagnetic vector field and the metric tensor field. We
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Slowly rotating and charged black-holes in entangled relativity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-04 Maxime Wavasseur, Théo Abrial, Olivier Minazzoli
Entangled Relativity is a non-linear reformulation of Einstein’s General Theory of Relativity (General Relativity) that offers a more parsimonious formulation. This non-linear approach notably requires the simultaneous definition of matter fields, thus aligning more closely with Einstein’s principle of relativity of inertia than General Relativity does. Solutions for spherically charged black holes
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Periodic orbits of neutral test particles in Reissner–Nordström naked singularities Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-04 Zoe C. S. Chan, Yen-Kheng Lim
We conduct studies on Levin’s taxonomy of periodic orbits for neutral test particles around a Reissner-Nordström naked singularity. It was known that naked singularities could harbor two distinct regions of time-like bound orbits and thus we expect periodic orbits to appear in both regions. It is possible for a pair of periodic orbits from both regions to possess the exact same angular momentum L and
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Generation of effective massive Spin-2 fields through spontaneous symmetry breaking of scalar field Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-05 Susobhan Mandal, S. Shankaranarayanan
General relativity and quantum field theory are the cornerstones of our understanding of physical processes, from subatomic to cosmic scales. While both theories work remarkably well in their tested domains, they show minimal overlap. However, our research challenges this separation by revealing that non-perturbative effects bridge these distinct domains. We introduce a novel mechanism wherein, at
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Taming the classically divergent curvature in self-adjoint quantum black holes Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-03 Harpreet Singh, Malay K. Nandy
It is well-known that the Kretschmann curvature diverges strongly at the classical singularity of the black hole interior. In this paper, we are therefore interested in whether such a strong divergence can be tamed quantum mechanically in the vicinity of the black hole singularity. For this purpose, we consider DeWitt-regular quantum black hole solutions of a self-adjoint Wheeler–DeWitt equation originating
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The confluent Heun functions in black hole perturbation theory: a spacetime interpretation Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-04 Marica Minucci, Rodrigo Panosso Macedo
This work provides a spacetime interpretation of the confluent Heun functions within black hole perturbation theory (BHPT) and explores their relationship to the hyperboloidal framework. In BHPT, the confluent Heun functions are solutions to the radial Teukolsky equation, but they are traditionally studied without an explicit reference to the underlying spacetime geometry. Here, we show that the distinct
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Geometry from geodesics: fine-tuning Ehlers, Pirani, and Schild Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-02 James T. Wheeler
Ehlers, Pirani, and Schild argued that measurements of null and timelike geodesics yield Weyl and projective connections, respectively, with compatibility in the lightlike limit giving an integrable Weyl connection. Their conclusions hold only for a 4-dim representation of the conformal connection on the null cone, and by restricting reparameterizations of timelike geodesics to yield a torsion-free
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The backreaction problem for black holes in semiclassical gravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-02-01 Adrian del Rio
The question of black hole evaporation is reviewed in the framework of quantum field theory in curved spacetimes and semiclassical gravity. We highlight the importance of taking backreaction effects into account to have a consistent picture of the fate of gravitational collapse in this framework. We describe the difficulties of solving the backreaction semiclassical equations due to practical complications
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Dynamics of redshift/blueshift during free fall under the Schwarzschild horizon Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-31 H. V. Ovcharenko, O. B. Zaslavskii
We consider a free-falling observer who crosses the event horizon in the Schwarzschild background. In the course of this fall, he/she can receive signals from an object (like a star surface) that emits radiation. We study how the frequency received by an observer changes depending on the proper time on his/her trajectory. The scenarios are classified depending on whether the frequency is infinite,
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Lorentzian Robin Universe of Gauss-Bonnet Gravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-31 Manishankar Ailiga, Shubhashis Mallik, Gaurav Narain
The gravitational path-integral of Gauss–Bonnet gravity is investigated and the transition from one spacelike boundary configuration to another is analyzed. Of particular interest is the case of Neumann and Robin boundary conditions which is known to lead to a stable Universe in Einstein–Hilbert gravity in four spacetime dimensions. After setting up the variational problem and computing the necessary
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Gravitational reduction of the wave function through the quantum theory of motion Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-29 Faramarz Rahmani
We present a novel perspective on gravity-induced wave function reduction using Bohmian trajectories. This study examines the quantum motion of both point particles and objects, identifying critical parameters for the transition from quantum to classical regimes. By analyzing the system’s dynamics, we define the reduction time of the wave function through Bohmian trajectories, introducing a fresh viewpoint
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Quantum theory of the Lemaître model for gravitational collapse Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-28 Claus Kiefer, Hamid Mohaddes
We investigate the quantum fate of the classical singularities that occur by gravitational collapse of a dust cloud. For this purpose, we address the quantization of a model first proposed by Georges Lemaître in 1933. We find that the singularities can generically be avoided. This is a consequence of unitary evolution in the quantum theory, whereby the quantum dust cloud collapses, bounces at a minimal
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Inflation and acceleration of the universe from nonminimal coupling gravity with nonlinear electrodynamics Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-23 Chilwatun Nasiroh, Ramy F. Izzah, Fiki T. Akbar, Bobby E. Gunara
In this paper, we consider a nonminimal coupling model between gravity and nonlinear electrodynamics with cosmological constant. This cosmological model is designed to account for both the inflationary epoch of the early universe and the current phase of accelerated cosmic expansion. The nonlinear electrodynamic fields provide a mechanism for a graceful exit from the inflationary period, preventing
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Non-commutative classical and quantum fractionary cosmology: anisotropic Bianchi type I case Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-24 J. Socorro, J. Juan Rosales, Leonel Toledo Sesma
In this work, we explore non-commutative effects in fractional classical and quantum schemes using the anisotropic Bianchi type I cosmological model coupled to a scalar field in the K-essence formalism. We introduce non-commutative variables considering that all minisuperspace variables \(q^{i}_{nc}\) do not commute, so the symplectic structure was modified, resulting in some changes concerning the
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Simulating black hole imposters Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-24 Frans Pretorius
I briefly describe motivation for, and the current state of research into understanding the structure and dynamics of black hole “imposters”: objects that could be misidentified as Kerr black holes given the current precision of LIGO/Virgo gravitational wave observations, or EHT accretion disk measurements. I use the term “weak imposter” to describe an object which is a black hole, i.e. it has an event
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Quantum black holes: from regularization to information paradoxes Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-24 Niayesh Afshordi, Stefano Liberati
Quantum black holes, a broad class of objects that refine the solutions of general relativity by incorporating semiclassical and/or quantum gravitational effects, have recently attracted renewed attention within the scientific community. This resurgence of interest is largely driven by advances in gravitational wave astronomy, which have opened the possibility of testing some of these models in the
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Horizon-bound objects: Kerr–Vaidya solutions Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-22 Pravin K. Dahal, Swayamsiddha Maharana, Fil Simovic, Daniel R. Terno
Kerr–Vaidya metrics are the simplest dynamical axially-symmetric solutions, all of which violate the null energy condition and thus are consistent with the formation of a trapped region in finite time according to distant observers. We examine different classes of Kerr–Vaidya metrics, and find two which possess spherically-symmetric counterparts that are compatible with the finite formation time of
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Covariant single-field formulation of effective cosmological bounces Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-22 Marcello Miranda
This study explores the feasibility of an effective Friedmann equation in removing the classical Big Bang initial singularity and replacing it with a non-singular bounce occurring at a critical energy density value. In a spatially flat, homogeneous, and isotropic universe, the effective theory is obtained by introducing a function parametrically dependent on the critical energy density. This function
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On the origin and fate of our universe Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-20 Cumrun Vafa
This brief review, intended for high energy and astrophysics researchers, explores the implications of recent theoretical advances in string theory and the Swampland program for understanding bounds on the structure of positive potentials allowed in quantum gravity. This has a bearing on both inflationary models for the early universe as well as the fate of our universe. The paper includes a review
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Mass and topology of hypersurfaces in static perfect fluid spaces Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-20 Maria Andrade, Benedito Leandro, Thamara Policarpo
We investigate the topological implications of stable minimal surfaces existing in a static perfect fluid space while ensuring that the fluid satisfies certain energy conditions. Based on the main findings, the topology of the level set \(\{f=c\}\) (the boundary of a stellar model) is studied, where c is a positive constant and f is the static potential of a static perfect fluid space. Bounds for the
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A Background Independent Algebra in Quantum Gravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-18 Edward Witten
I consider the algebra of operators along the world line of an observer as a background independent algebra in quantum gravity.
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Differential curvature invariants and event horizon detection for accelerating Kerr–Newman black holes in (anti-)de Sitter spacetime Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-16 G. V. Kraniotis
We compute analytically differential curvature invariants for accelerating, rotating and charged black holes with a cosmological constant \(\varLambda \). Specifically, we compute novel closed-form expressions for the Karlhede and the Abdelqader-Lake invariants, for accelerating Kerr–Newman black holes in (anti-)de Sitter spacetime or subsets thereof with the aim of detecting physically relevant surfaces
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Kaluza–Klein bubble with massive scalar field Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-15 Darrell Jackson
A well-known soliton (bubble) solution of five-dimensional Kaluza–Klein General Relativity is modified by imposing mass on the scalar field. By forcing the scalar field to be short-range, the failure of the original bubble solution to satisfy the equivalence principle is remedied, and the bubble acquires gravitational mass. Most importantly, the mass is quantized, even in this classical setting, and
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Cosmic evolution of Bianchi III model within Born-Infeld f(R) gravity theory Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-13 Debika Kangsha Banik, Sebika Kangsha Banik, Kalyan Bhuyan
In this paper, we have put forwarded a detailed investigation on the cosmic evolution of Bianchi type III model within the realm of Born-Infeld f(R) gravity executing the Palatini approach. Using a very eminent tool known as Dynamical System Approach (DSA), we have curtailed the complexity of the non linear field equations and study the dynamics for the form \(f(R) =R-\beta / R^n\). The main focus
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Same as ever: looking for (in)variants in the black holes landscape Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-13 Carlos A. R. Herdeiro
Abstract "Is it a goose, a duck or a swan?"—asked the alien. "I do not know; and to know we have to look closer."—said the earthling. "But even from here we can see it has webbed feet... so it is not a chicken." Graphical Abstract
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Black holes beyond General Relativity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-13 Enrico Barausse, Jutta Kunz
Here, we will discuss some ideas for possible classical/semi-classical modifications of the black hole solutions in General Relativity (GR). These modifications/extensions include black holes in higher dimensions; black holes with additional gravitational fields, or fields beyond the Standard Model of Particle Physics; black holes in alternative classical theories of gravity and in semiclassical gravity;
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Dynamics of the temporal evolution in radiating stars Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-10 S. D. Maharaj, K. S. Govinder
We study the dynamics of a charged radiating star in general relativity. The junction conditions at the surface of the star lead to a restriction that connects the radial pressure to the heat flux. The master equation reduces to a nonlinear second order differential equation which determines the temporal evolution. The dynamical behaviour is studied via a phase plane analysis which reveals interesting
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Thermodynamics as a framework for understanding gravitational dynamics and quantum gravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2025-01-08 Ana Alonso-Serrano, Marek Liška
We present a review of concepts of thermodynamic of spacetime that allows for an understanding of the gravitational dynamics encoding in it, discussing also the recovery of Weyl transverse gravity instead of General Relativity. We also discuss how these tools can provide some hints in the search of quantum gravity phenomenology, by introducing a formalism to analyze low-energy quantum gravity modifications
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Linearized stability of Harada thin-shell wormholes Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-30 Hassan Alshal, Leyang Ding, Adelina Hernandez, Leo A. Illing, Ivar Rydstrom
Using Darmois-Israel-Sen junction conditions, and with help of Visser’s cut-and-paste method, we study the dynamics of thin-shell wormholes that are made of two conformally Killing gravity (a.k.a Harada gravity) black holes. We check the energy conditions for different values of the new parameter that Harada introduced, as alternative for dark energy. We examine the radial acceleration to reveal the
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Euler-heisenberg black holes in einsteinian cubic gravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-28 Gustavo Gutierrez-Cano, Gustavo Niz
We explore black hole solutions and some of its physical properties in Einstein’s theory in 4D, modified by a cubic gravity term and in the presence of non-linear electrodynamics. In the context of Effective Field Theories (EFT) and under certain assumptions, these curvature and non-linear electromagnetic terms represent the first corrections to the Einstein-Maxwell theory. We obtain static and spherically
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On the interrelation of the generalized holographic equipartition and entropy maximization in Kaniadakis paradigm Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-26 Pranav Prasanthan, Sarath Nelleri, Archana K. Pradeepan, Navaneeth Poonthottathil, Emmanuel Tom
This study examines the compatibility of the generalized holographic equipartition proposed in Sheykhi (Phys Rev D 87(6):061501, 2013) with the maximization of horizon entropy in an (n + 1)-dimensional non-flat Friedmann–Robertson–Walker (FRW) universe. Here, the entropy associated with the apparent horizon is described by Kaniadakis entropy, as well as truncated Kaniadakis entropy, which is expanded
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Free fall in modified symmetric teleparallel gravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-27 Nivaldo A. Lemos
The status of the equivalence principle in modified symmetric teleparallel gravity is examined. In this theory, minimum length geodesics are distinct from autoparallel geodesics, that is, the “shortest” paths are not the “straightest” paths. We show that a standard argument that singles out metric geodesics in general relativity does not apply in modified symmetric teleparallel gravity. This is because
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White Dwarf envelops and temperature corrections in exponential f(T) gravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-24 Gabriel Farrugia, Carlos Gafa’, Jackson Levi Said
Compact stars have long served as a test bed of gravitational models and their coupling with stellar matter. In this work, we explore the behavior of an exponential model in f(T) gravity through the Tolman-Oppenheimer-Volkoff equation. This is performed for different envelope thicknesses. Finally, constraints on the models parameters are obtained, which are comparable to the results obtained using
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Towards the entanglement entropy of two quantum black holes Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-23 J. Ríos–Padilla, O. Obregón, J. C. López–Domínguez
Starting from a Wheeler–DeWitt type equation for an uncharged black hole \(Q=0\), and by choosing the order parameter \((s=2)\) and running the gravitational degrees of freedom it is possible to reduce the Wheeler–DeWitt equation to the canonical form of a quantum harmonic oscillator. In this direction, a natural frequency of oscillation is identified for the black hole. The entanglement entropy of
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Quantum gravity, hydrodynamics and emergent cosmology: a collection of perspectives Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-18 Jibril Ben Achour, Dario Benedetti, Martin Bojowald, Robert Brandenberger, Salvatore Butera, Renata Ferrero, Flaminia Giacomini, Kristina Giesel, Christophe Goeller, Tobias Haas, Philipp A. Höhn, Joshua Kirklin, Luca Marchetti, Daniele Oriti, Roberto Percacci, Antonio D. Pereira, Andreas G. A. Pithis, Mairi Sakellariadou, Sebastian Steinhaus, Johannes Thürigen
This collection of perspective pieces captures recent advancements and reflections from a dynamic research community dedicated to bridging quantum gravity, hydrodynamics, and emergent cosmology. It explores four key research areas: (a) the interplay between hydrodynamics and cosmology, including analog gravity systems; (b) phase transitions, continuum limits and emergent geometry in quantum gravity;
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How the black hole puzzles are resolved in string theory Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-19 Samir D. Mathur
String theory has provided a resolution of the puzzles that arise in the quantum theory of black holes. The emerging picture of the hole, encoded in the ‘fuzzball paradigm’, offers deep lessons about the role of quantum gravity on macroscopic length scales. In this article we list these puzzles and explain how they get resolved. We extract the lessons of this resolution in a form that does not involve
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Inhomogeneous brane models Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-17 Pantelis S. Apostolopoulos, Noeleen Naidoo
The existence of a set of 10 Intrinsic Conformal Symmetries, which acts on three-dimensional hypersurfaces (spacelike or timelike), leads to the existence of two distinct families of 5D geometries. These models represent the general solutions of the bulk field equations where their energy-momentum tensor, includes only two components: a negative cosmological constant and a parallel pressure \(p_{\parallel
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Tests of general relativity with future detectors Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-12 Emanuele Berti
This "vision document" is about what the future has in store for tests of general relativity with gravitational wave detectors. I will make an honest attempt to answer this question by addressing the role of inspiral-based and ringdown-based tests; recent progress on quasinormal modes in modified theories of gravity; the complementarity between light ring tests and ringdown tests; and the interesting
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Black holes, Cauchy horizons, and mass inflation Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-12 Matt Visser
Event horizons and Cauchy horizons are highly idealized mathematical constructions that do not fully capture the key physics of either Hawking radiation or mass inflation. Indeed, because they are teleological, both event horizons and Cauchy horizons are (in a precise technical sense) not physically observable. In contrast, by inspecting the quasi-local behaviour of null geodesics, long-lived apparent
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Low-temperature holographic screens correspond to einstein-rosen bridges Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-09 Marco Alberto Javarone
Recent conjectures on the complexity of black holes suggest that their evolution manifests in the structural properties of Einstein-Rosen bridges, like the length and volume. The complexity of black holes relates to the computational complexity of their dual, namely holographic, quantum systems identified via the Gauge/Gravity duality framework. Interestingly, the latter allows us to study the evolution
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Hawking radiation with pure states Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-08 K. Sravan Kumar, João Marto
Hawking’s seminal work on black hole radiation highlights a critical issue in our understanding of quantum field theory in curved spacetime (QFTCS), specifically the problem of unitarity loss (where pure states evolve into mixed states). In this paper, we examine a recent proposal for a direct-sum QFTCS, which maintains unitarity through a novel quantization method that employs geometric superselection
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Quasitopological Lifshitz dilaton black brane Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-12-07 A. Bazrafshan, M. Ghanaatian, S. Rezaei, Gh. Forozani
We construct a new class of \((n+1)\)-dimensional Lifshitz dilaton black brane solutions in the presence of the cubic quasitopological gravity for a flat boundary. The related action supports asymptotically Lifshitz solutions by applying some conditions which are used throughout the paper. We have to add a new boundary term and some new counterterms to the bulk action to have finite solutions. Then
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Bose-Einstein condensate stars in combined Rastall-Rainbow gravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-22 O. P. Jyothilakshmi, Lakshmi J. Naik, V. Sreekanth
We study zero and finite temperature static Bose-Einstein condensate (BEC) stars in the combined Rastall-Rainbow (RR) theory of gravity by considering different BEC equation of states (EoSs). We obtain the global properties of BEC stars by solving the modified Tolman-Oppenheimer-Volkoff equations of RR gravity with values of Rastall parameter \(\kappa \) and Rainbow function \(\Sigma \) chosen accordingly
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Joule-thomson expansion of vanished cooling region for five-dimensional neutral Gauss-Bonnet AdS black hole Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-18 Tian-Yu Liu
This paper investigates the Joule-Thomson expansion for a five-dimensional neutral Gauss-Bonnet Anti-de Sitter black hole. Firstly, by taking Van der Waals gas as an example, we induce the definition of the Joule-Thomson coefficient and the inversion phenomena. One can give the T–P graph and the inversion curves. Then, we obtain the thermodynamic properties of the Gauss-Bonnet black hole and use the
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GUP deformed background dynamics of phantom field Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-16 Gaurav Bhandari, S. D. Pathak, Manabendra Sharma, Anzhong Wang
Quantum gravity has been baffling the theoretical physicist for decades now, both for its mathematical obscurity and phenomenological testing. Nevertheless, the new era of precision cosmology presents a promising avenue to test the effects of quantum gravity. In this study, we consider a bottom-up approach. Without resorting to any candidate quantum gravity, we invoke a generalized uncertainty principle
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Role of dynamical vacuum energy in the closed universe: implications for bouncing scenario Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-14 Ashutosh Singh
We consider a homogeneous and isotropic spacetime having a space of positive curvature and study the cosmic evolution of dynamical vacuum energy. We utilize the dynamical system technique to study the existence of fixed points and their corresponding stability in model. The corresponding cosmological solutions describe late-time accelerating universe having decelerating era composed of radiation and
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Novel approach to solving Schwarzschild black hole perturbation equations via physics informed neural networks Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-10 Nirmal Patel, Aycin Aykutalp, Pablo Laguna
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The black-hole limits of the spherically symmetric and static relativistic polytrope solutions Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-07 Jorge L. deLyra
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The study of the canonical forms of Killing tensor in vacuum with $$\Lambda $$ Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-06 D. Kokkinos, T. Papakostas
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Height-function-based 4D reference metrics for hyperboloidal evolution Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-07 Alex Vañó-Viñuales, Tiago Valente
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Again about singularity crossing in gravitation and cosmology Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-11-02 Alexander Kamenshchik
We discuss the problem of singularity crossing in isotropic and anisotropic universes. We study at which conditions singularities can disappear in quantum cosmology and how quantum particles behave in the vicinity of singularities. Some attempts to develop general approach to the connection between the field reparametrization and the elimination of singularities is presented as well.
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Colliding gravitino plane waves in $$N=1$$ supergravity Gen. Relativ. Gravit. (IF 2.1) Pub Date : 2024-10-29 Tekin Dereli, Yorgo Şenikoğlu