Article
Astronomy & Astrophysics
Fabio M. Mele, Johannes Muench, Stratos Pateloudis
Summary: In this paper, the authors continue the analysis of the effective model of quantum Schwarzschild black holes. They find that the central singularity is resolved in the quantum-corrected spacetime and quantum effects become relevant at a mass-independent curvature scale. They focus on the thermodynamic properties of the effective polymer black hole and analyze the quantum corrections as functions of black and white hole masses. The study reveals an extremal minimal-sized configuration characterized by vanishing temperature and entropy. For large masses, the classical results are recovered and quantum corrections are negligible.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Antonio De Felice, Andreas Doll, Francois Larrouturou, Shinji Mukohyama
Summary: This study investigates spherically symmetric vacuum solutions in the context of the recently proposed type-II minimally modified gravity theory. Despite local differences from the traditional metric, the solutions can be recovered to the standard metric by imposing suitable asymptotic conditions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Jitendra Kumar, Shafqat Ul Islam, Sushant G. Ghosh
Summary: In this study, a rotating black hole metric is constructed based on the research of LQG black holes, which exhibits rich spacetime structures and differs from Kerr black holes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
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
Astronomy & Astrophysics
Alejandro Perez, Salvatore Ribisi, Sami Viollet
Summary: In this paper, a solvable toy model is constructed to describe the quantum dynamics of the interior of a spherical black hole with falling spherical scalar field excitations. The quantum gravity dynamics of realistic black holes emitting Hawking radiation is modeled using Kantowski-Sachs solutions with a massless scalar field when focusing on the deep interior region. The KS model becomes exactly solvable at both the classical and quantum levels in the suitable variables in the regime where r K M.
Article
Astronomy & Astrophysics
Kunal Pal, Kuntal Pal, Rajibul Shaikh, Tapobrata Sarkar
Summary: By observing the shadows of M87* and Sgr A*, we studied a rotating version of a modified Janis-Newman-Winicour metric and constrained the size of the wormhole using parameter values. The results show that the case of a naked singularity is inconsistent with the observations, while the shadow formed by the wormhole branch is consistent with the observations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Naritaka Oshita, Niayesh Afshordi, Shinji Mukohyama
Summary: This study investigates the ringdown waveform and reflectivity of a Lifshitz scalar field around a fixed Schwarzschild black hole, finding that Lifshitz waves scattered by the black hole exhibit superradiance due to Lorentz breaking terms leading to superluminal propagation. This can allow Lifshitz waves to carry additional positive energy to infinity while leaving negative energy inside the Killing horizon, similar to the Penrose process in Kerr spacetime. The study also observes the emergence of long-lived quasinormal modes and drastic modifications to the greybody factor of a microscopic black hole with Hawking temperature comparable to the Lifshitz energy scale.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
R. Casadio, R. da Rocha, P. Meert, L. Tabarroni, W. Barreto
Summary: Two types of information entropy in the quantum states of a black hole's matter core are studied. The quantum mechanical picture of a collapsing ball of dust in general relativity, including a non-trivial ground state and a spectrum of bound states, is described. Computed information entropies shed new light on the stability of the ground state and the spectrum of higher excited states.
CLASSICAL AND QUANTUM GRAVITY
(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
Astronomy & Astrophysics
Sina Kazemian, Mateo Pascual, Carlo Rovelli, Francesca Vidotto
Summary: The existence of an area gap as predicted by loop quantum gravity removes a main objection to the scenario where a black hole may leave a remnant with a large amount of stored information at the end of its evaporation. We have modeled the emission from these remnants and derived properties of the diffuse radiation emitted by a population of such objects. By measuring the frequency and energy density of this radiation, it is possible to estimate the mass of the parent black holes and the remnant density, if the age of the population is known.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Astrid Eichhorn, Aaron Held
Summary: This paper investigates the true nature of black holes by constructing regular black-hole spacetimes based on new-physics models, characterizing them by curvature invariants, and analyzing features such as the shadow shape and photon rings. Simulated images of the regular spinning black hole are generated to test the visibility of characteristic features in the intensity map, providing insights into the new-physics effects.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Multidisciplinary
J. R. M. de Nova, P. F. Palacios, I Carusotto, F. Sols
Summary: This study examines the instability spectrum and time evolution of a flowing quantum gas in a black-hole laser configuration, providing a theoretical tool for identification of black-hole lasing in future experiments. The research confirms the presence of a well-defined phase diagram at long times, indicating universality in the long-time behavior of a black-hole laser.
NEW JOURNAL OF PHYSICS
(2021)
Review
Physics, Particles & Fields
Thomas G. G. Mertens, Gustavo J. J. Turiaci
Summary: We review recent developments in Jackiw-Teitelboim gravity, a simple solvable model of quantum gravity in two dimensions. It has been proven to be a fruitful toy model to analyze important questions such as the relation between black holes and chaos, the role of wormholes in black hole physics and holography, and the recovery of information that falls into a black hole.
LIVING REVIEWS IN RELATIVITY
(2023)
Article
Physics, Particles & Fields
Kanato Goto, Thomas Hartman, Amirhossein Tajdini
Summary: This paper investigates replica wormholes for black holes formed by gravitational collapse in Jackiw-Teitelboim gravity, confirming that they lead to the island rule for entropy. The main technical challenge lies in the fact that replica wormholes rely on a Euclidean path integral, while the quantum extremal islands of an evaporating black hole exist only in Lorentzian signature.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Ruben Campos Delgado, Sergei V. Ketov
Summary: In this study, we investigate the physical properties of a Schwarzschild-type black hole in the framework of the recently proposed Starobinsky-Bel-Robinson (SBR) modified theory of gravity. We compute the temperature, entropy, pressure, and lifetime of the black hole using perturbation theory in the coupling constant.
Article
Astronomy & Astrophysics
Bogeun Gwak
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2019)
Article
Physics, Multidisciplinary
Bogeun Gwak
Article
Physics, Nuclear
Bogeun Gwak
Article
Physics, Nuclear
Bogeun Gwak
Summary: In the context of warped anti-de Sitter black holes within the framework of new massive gravity, the scattering of a massive scalar field can alter the state of the black hole by transferring conserved quantities. The changes observed in the black hole under scattering are consistent with the laws of thermodynamics, ensuring that the Hawking temperature remains non-zero and the black hole does not exceed the extremal condition.
Review
Physics, Multidisciplinary
Bogeun Gwak
Summary: This review briefly introduces particle absorption as a method for investigating the weak cosmic censorship conjecture for Kerr-(anti-)de Sitter black holes. The conjecture can be tested by perturbing the black hole with ingoing particles to determine the stability of its horizon. The analysis shows that the changes in black holes are consistent with the laws of thermodynamics.
JOURNAL OF THE KOREAN PHYSICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Bogeun Gwak
Summary: We investigate the weak cosmic censorship conjecture in extremal and near-extremal Kerr-Newman-(anti-)de Sitter black holes by scattering a massive scalar field with charge. While the black hole may exceed its extremal condition due to changes in its state caused by the scattering, it cannot be overcharged or overspun. The weak cosmic censorship conjecture is valid for any scalar field boundary conditions and is thermodynamically preferred for this scattering process.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Bogeun Gwak
Summary: We investigate the weak cosmic censorship conjecture in Myers-Perry black holes in general dimensions using the scattering of a massless scalar field. By analyzing the fluxes of the scalar field into the black hole and the changes in mass and angular momenta of the black hole, we find that the conjecture holds true. Moreover, the changes in the black hole are also examined from a thermodynamic perspective, which further supports the conjecture.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Bogeun Gwak, Naoto Kan, Bum-Hoon Lee, Hocheol Lee
Summary: This study investigates the conjectured bound on the Lyapunov exponent for a charged particle with angular motion in the Kerr-Newman-AdS black hole. The findings show that the negative cosmological constant reduces the chaotic behavior of the particle, resulting in a decrease in the Lyapunov exponent. However, the bound can be violated when the angular momenta of the black hole are turned on, particularly in an extremal black hole.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Multidisciplinary
Bogeun Gwak
Summary: We study the quasinormal modes of the spinning C-metric with a massless scalar field conformally coupled with gravity. By employing conformal transformation, we are able to separate and solve the massless scalar field equations. As the outer and acceleration horizons approach each other, the potential term of the field equation reduces to the Poshl-Teller potential due to the similarity between the acceleration horizon and the cosmological horizon of de Sitter spacetime. Finally, we obtain the analytical quasinormal frequency at which the decay rate is quantized.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Physics, Particles & Fields
Hyewon Han, Bogeun Gwak
Summary: We studied the effects of metric fluctuations on the geometry of higher-dimensional black holes and extended the four-dimensional model to higher dimensions to account for quantum vacuum fluctuations. Using a perturbation method for small fluctuation amplitudes, we obtained the null geodesic equation for radially outgoing rays up to second order in the fluctuations. The fluctuation of the event horizon and the thermodynamic variables defined at the horizon also have dimension-dependent correction terms up to second order. A general solution for rays propagating near the horizon in a fluctuating geometry was derived, and in the large D limit, a compact form solution was found.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Naoto Kan, Bogeun Gwak
Summary: We investigate the conjecture on the upper bound of the Lyapunov exponent for the chaotic motion of a charged particle around a Kerr-Newman black hole. Through considering the angular momenta, we find that the Lyapunov exponent can exceed the conjectured upper bound, and the location of the maximum is related to the value of the Lyapunov exponent and the extremal and nonextremal states of the black hole.
Article
Astronomy & Astrophysics
Supakchai Ponglertsakul, Bogeun Gwak
Summary: This study investigates a scalar field propagating in a higher-dimensional black hole, exploring various definitions of black hole temperatures and the impact of scalar field couplings on different properties. It is found that bulk dominance may be possible under certain temperature definitions and ranges of the cosmological constant.
Article
Physics, Particles & Fields
Supakchai Ponglertsakul, Bogeun Gwak
EUROPEAN PHYSICAL JOURNAL C
(2020)
Article
Astronomy & Astrophysics
Yongwan Gim, Bogeun Gwak
