Article
Astronomy & Astrophysics
Ana Alonso-Serrano, Marek Liska
Summary: This work is based on a formalism developed in the study of spacetime thermodynamics to derive Einstein equations from entropy proportionality within an area. It introduces an additional logarithmic term in the entropy expression when considering low-energy quantum gravity effects. The derivation of quantum modified gravitational dynamics from this modified entropy expression is presented, along with its main features. The application of the modified dynamics to cosmology, suggesting a regular bounce instead of the Big Bang singularity, is also outlined.
Article
Physics, Particles & Fields
Everett Patterson, Robert B. Mann
Summary: Relativistic quantum metrology is the study of optimal measurement procedures in systems with quantum and relativistic components. In this study, we analyze thermal parameters in different spacetimes using Unruh-DeWitt detectors coupled to a massless scalar field. We consider both (2+1)-dimensional anti-de Sitter and BTZ black hole spacetimes and compute the Fisher information to identify characteristics and maximize precision.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Roberto Casadio
Summary: Classical general relativity predicts the occurrence of spacetime singularities under very general conditions. However, from the perspective of the complete quantum theory of matter and gravity, it is argued that this scenario cannot be physically realized since no proper quantum state may contain the infinite momentum modes required to resolve the singularity.
Article
Physics, Particles & Fields
Isaac Layton, Jonathan Oppenheim, Andrea Russo, Zachary Weller-Davies
Summary: In this paper, we derive the Newtonian limit of classical-quantum theories of gravity and compare it to previous models. The results show that the weak field dynamics differs from previous models. We also propose a system of stochastic differential equations for the trajectory of the hybrid classical-quantum state and provide a series of kernels for constructing figures of merit to experimentally test the parameter space of classical-quantum theories of gravity.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Roberto Casadio, Andrea Giusti, Jorge Ovalle
Summary: We study black holes formed by quantum matter with regular wavefunctions. This leads to integrable energy densities and the absence of Cauchy horizons in spherically symmetric configurations. Additionally, we discover that the ultrarigid rotation of Kerr spacetime results in the presence of an inner horizon in rotating systems, and we analyze the general properties of quantum matter cores at the center of rotating black holes, which exhibit integrable singularities and no Cauchy horizon.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Keagan Blanchette, Saurya Das, Saeed Rastgoo
Summary: The study investigates the generic corrections to the Raychaudhuri equation inside a Schwarzschild black hole due to modifications inspired by generalized uncertainty principle (GUP) theories. It shows that two specific models of GUP lead to finite Kretchmann scalar, expansion, and its rate, resolving the singularity issue.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Mathematical
Roberto Casadio
Summary: Researchers attempt to reconstruct the state of a Schwarzschild black hole by analyzing a collapsing ball of dust and describing the outer geometry using a coherent state.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Physics, Particles & Fields
Jacopo Mazza, Stefano Liberati
Summary: There is increasing evidence that Horava gravity is a viable quantum theory of gravity. This suggests that gravitational collapse in the non-projectable version of the theory should result in geometries without space-time singularities. Previous studies have identified different classes of such geometries, including regular black holes, non-connected black holes with wormhole mouths, and horizonless compact objects. This study focuses on a singular black hole in the low-energy limit of non-projectable Horava gravity, exploring examples of its regularizations within all viable classes. These examples are the first instances of black holes with inner universal horizons, black bounces, and stars with a de Sitter core in the context of Lorentz-violating theories of gravity.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Isaac Layton, Jonathan Oppenheim, Andrea Russo, Zachary Weller-Davies
Summary: Consistent coupling between quantum and classical degrees of freedom is achieved when there is diffusion of classical degrees of freedom and decoherence of the quantum system. This paper derives the Newtonian limit of classical-quantum (CQ) theories of gravity and finds that the Newtonian potential diffuses into mass eigenstates due to decoherence. The results are presented as a set of stochastic differential equations and can be used to experimentally test and eliminate certain parameter spaces of classical-quantum theories of gravity through the trade-off between decoherence and diffusion.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Radouane Gannouji, Yolbeiker Rodriguez Baez
Summary: This study examines the stability of static black holes in generalized Einstein-Maxwell-scalar theories. The master equations for odd and even parity perturbations are derived, and the sufficient and necessary conditions for the stability of black holes under odd-parity perturbations are determined. Interestingly, these conditions are often dissimilar to energy conditions, even in the simplest case. The necessary conditions for the stability of even-parity perturbations are also obtained, along with the speed of propagation of the five degrees of freedom. The study applies these findings to various black holes in nonlinear electrodynamics, scalar-tensor theories, and Einstein-Maxwell-dilaton theory, including the calculation of quasinormal modes.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Rong-Gen Cai, Chenghu Ge, Li Li, Run-Qiu Yang
Summary: This study investigates the internal structure of anisotropic black holes with charged vector hairs. It presents the discovery of radially conserved charges and provides a general proof of no inner horizon for these black holes. The study also reveals multiple intermediate regimes and phenomena such as oscillations of vector condensate and spatial geometry.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Fil Simovic, Danny Fusco, Robert B. Mann
Summary: The thermodynamic properties of 3+1 dimensional black holes conformally coupled to a real scalar field in asymptotically de Sitter spacetimes were investigated using a Euclidean action approach. By treating the cosmological constant as a thermodynamic pressure in the extended phase space, phase transitions resembling Hawking-Page transitions were observed in the black hole solutions, with the existence of these transitions further depending on a specific cosmic censorship bound.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Gokhan Alkac, Mehmet Kemal Gumus, Mustafa Tek
Summary: The Kerr-Schild double copy provides a map between exact solutions of general relativity and Maxwell's theory, showing the effect of curvature on gauge theory sources, and demonstrating the existence of constant charge density in solutions with curved backgrounds. By studying examples like the Lifshitz black hole, the paper highlights the cancellation of the constant charge density by contributions from matter fields, providing insights into non-localized source terms in vacuum gravity solutions corresponding to vacuum gauge theory solutions in arbitrary dimensions.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Hideki Maeda
Summary: In this paper, seven criteria are proposed to identify physically reasonable non-singular black hole models. These criteria are applied to four different spherically symmetric models, leading to the elimination of certain well-known non-singular black holes. The remaining models that satisfy the dominant energy condition and have no significant curvature singularities or closed timelike curves are discussed. However, the presence of parallelly propagated curvature singularities remains an open question.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Rong-Gen Cai, Li Li, Run-Qiu Yang
Summary: This study establishes a no inner-horizon theorem for black holes with charged scalar hairs, showing that they do not have an inner Cauchy horizon. The geometry near the singularity takes a universal Kasner form when the kinetic term of the scalar hair dominates, and novel behaviors are uncovered when the scalar potential becomes important. For hyperbolic horizon cases, hairy black holes can only have at most one inner horizon. These features also apply to Einstein gravity coupled with neutral scalars.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)