Article
Physics, Particles & Fields
Haryanto M. Siahaan
Summary: This study explores the holographic picture for the Kerr-de Sitter spacetime with multiple horizons, demonstrating the existence of hidden conformal symmetry for both black hole and cosmological horizons. Scalar scattering calculations are used in the near region of each horizon to support the holographic approach, showing that the cosmological horizon entropy and associated scalar scattering can be understood through a two-dimensional conformal field theory.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
Javlon Rayimbaev, Sanjar Shaymatov, Mubasher Jamil
Summary: This paper investigates circular orbits around a black hole surrounded by dark matter, showing how dark matter impacts the existence of circular orbits and exploring its applications in fitting and explaining black hole parameters.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Abhishek Mathur, Sumati Surya, X. Nomaan
Summary: In this study, we calculate the manifestly covariant entanglement entropy S for a massive and massless minimally coupled free Gaussian scalar field on the de Sitter horizon and Schwarzschild de Sitter horizons, respectively. The calculations show that S for the mixed state is independent of the effective mass and matches the results obtained by Higuchi and Yamamoto. By using a cut-off in the angular modes, it is found that S is proportional to the area of the respective horizons.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Physics, Multidisciplinary
Eunice Omwoyo, Humberto Belich, Julio C. Fabris, Hermano Velten
Summary: Analytical solutions using Jacobi elliptic functions for bound and nearly bound photon orbits in Kerr-de Sitter and Kerr-de Sitter revisited spacetimes are derived in this paper. Analytic ray-tracing is conducted based on the obtained solutions in both spacetimes. Direct images, lensing rings and photon rings for equatorial disks are obtained for inclined locally static observers. The images corresponding to n = (2, 3) exhibit a significantly closer resemblance to the critical curve, showcasing the potential of these higher-order images as robust testing grounds for general relativity.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Astronomy & Astrophysics
Emil T. Akhmedov, Kirill V. Bazarov
Summary: In this paper, we study a quantum real massive scalar field in the de Sitter-Schwarzschild spacetime background. To make analytical progress, we focus on the two-dimensional case, assuming that the situation in four dimensions will be similar conceptually. We assume the quantum field to be in a thermal state, described by the Planckian distribution for the exact modes in the given geometry. We approximately calculate the expectation value of the stress-energy tensor near the cosmological and black hole horizons. It is found that the geometry is strongly modified by the quantum fluctuations of the matter fields, due to the backreaction from quantum fields with a generic temperature.
Article
Physics, Particles & Fields
Mohammad Reza Khosravipoor, Mehrdad Farhoudi
Summary: By implementing the gravitational decoupling method, the deformed AdS-Schwarzschild black hole solution with an additional gravitational source was found. The effect of the deformation parameter on the horizon structure, thermodynamics, and phase transition temperature was investigated.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Cheng-Yong Zhang, Peng Liu, Yun-Qi Liu, Chao Niu, Bin Wang
Summary: The study focuses on the fully nonlinear dynamics of spherically symmetric black hole spontaneous scalarization in Einstein-Maxwell-scalar theory. It is found that by adjusting the coupling function and black hole charge, the development and stabilization of hairy black holes can be influenced.
Article
Astronomy & Astrophysics
Aditya Sharma, Kinjal Banerjee, Jishnu Bhattacharyya
Summary: In this work, an alternative method is proposed to characterize the evolution of cosmological spacetimes evolving in the presence of a positive cosmological constant and matter satisfying reasonable energy conditions. By defining certain functions, the evolution towards the de Sitter spacetime can be manifested.
Article
Physics, Multidisciplinary
B. C. Lutfuoglu, B. Hamil, L. Dahbi
Summary: This study investigates the thermodynamics of a Schwarzschild black hole surrounded by quintessence matter with a deformation on the Heisenberg algebra. The temperature, entropy, and heat capacity functions of the black hole are obtained, showing upper and lower bound values based on the quintessence and deformed algebra. The corrected density of quintessence matter and the black hole's equation of state functions are derived and compared with standard Schwarzschild black holes with graphical methods, interpreting the quantum deformation effects.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Physics, Particles & Fields
Serena Giardino, Andrea Giusti, Valerio Faraoni
Summary: This article analyzes the stealth solutions of scalar-tensor gravity and less-known generalizations of de Sitter spaces, examining their potential role as thermal equilibria at non-zero temperature in the new first-order thermodynamics of scalar-tensor gravity. No stable equilibria are discovered, further confirming the exceptional status of general relativity as an equilibrium state in the landscape of gravity theories, as seen through the lens of first-order thermodynamics.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Diego Fernandez-Silvestre, Joshua Foo, Michael R. R. Good
Summary: The Schwarzschild-de Sitter metric provides a simple background for studying Hawking radiation. While the black hole temperature is typically higher than the cosmological horizon temperature, heat flow from the black hole horizon to the cosmological horizon can occur. This study investigates the accelerating boundary correspondence in SdS spacetime and finds the solutions for boundary dynamics, energy flux, and asymptotic particle spectrum. The particle distribution is globally non-thermal but asymptotically reaches equilibrium.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Joao P. B. Brito, Rafael P. Bernar, Luis C. B. Crispino
Summary: In this study, we investigate the scalar radiation emitted by a source orbiting a Schwarzschild-anti-de Sitter black hole in circular geodesics. We compare the emitted power with that in other spacetimes and find different patterns of enhancement depending on the multipole modes.
Article
Mathematics, Applied
Stefano Borghini, Piotr T. T. Chrusciel, Lorenzo Mazzieri
Summary: We establish a new uniqueness theorem for the three dimensional Schwarzschild-de Sitter metrics by developing new or improved tools, such as a reverse Lojasiewicz inequality. We also prove the smoothness of the set of maxima of the lapse when containing a topological hypersurface. These findings provide a new strategy for classifying well behaved static solutions of vacuum Einstein equations with a positive cosmological constant based on the geometry of the maximum-set of the lapse.
ARCHIVE FOR RATIONAL MECHANICS AND ANALYSIS
(2023)
Article
Astronomy & Astrophysics
D. Guerrero-Dominguez, P. Talavera
Summary: In this paper, we investigate two aspects of a black hole immersed in the Schwarzschild-de Sitter spacetime. Firstly, we discover a hidden conformal symmetry in the equation of motion for a massless scalar particle near the black hole horizon, when the two horizons satisfy a quadratic relation. Secondly, we present the leading quantum corrections to the entropy at large time in the semiclassical limit.
Article
Astronomy & Astrophysics
R. A. Konoplya, A. Zhidenko
Summary: This article proposes a simple metric which parameterizes spherically symmetric and asymptotically flat black holes, taking into account the post-Newtonian constraints and basic astrophysical characteristics. By varying the values of three parameters, two distinctive features can be obtained: the temperature and Hawking radiation of the black hole, as well as the outburst of overtones that are highly sensitive to small changes in the parameters.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)