Article
Physics, Particles & Fields
Masoud Ghezelbash, Haryanto M. Siahaan
Summary: A new class of exact solutions in the Einstein-Maxwell theory was discovered by applying the Ernst magnetization process to Kerr-Newman-Taub-NUT spacetimes. The solutions were found to be regular everywhere, and quasilocal conserved quantities, the corresponding Smarr formula, and the first law of thermodynamics were also identified for these spacetimes.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Mathematical
Oliver Petersen, Andras Vasy
Summary: It is proven in this paper that quasinormal modes (or resonant states) for linear wave equations in the subextremal Kerr and Kerr-de Sitter spacetimes are real analytic. The main novelty lies in the observation that the bicharacteristic flow associated with the linear wave equations for quasinormal modes, with respect to a suitable Killing vector field, exhibits a stable radial point source/sink structure rather than simply a generalized normal source/sink structure. The analyticity is then established based on a recent result in the microlocal analysis of radial points by Galkowski and Zworski. The results can be reformulated with respect to the standard Killing vector field.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2023)
Article
Physics, Mathematical
Siyuan Ma, Lin Zhang
Summary: In this work, the sharp global decay of the spin +/- s components, which are solutions to the Teukolsky equation, in the black hole exterior and on the event horizon of a slowly rotating Kerr spacetime, is derived. These estimates are generalized to any subextreme Kerr background under an integrated local energy decay estimate. The results apply to the scalar field (s = 0), the Maxwell field (s = 1), and the linearized gravity (s = 2), confirming the sharp decay law conjectured by Price. The analyses rely on a novel global conservation law for the Teukolsky equation, and this new approach can be used to derive the precise asymptotics for solutions to semilinear wave equations.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2023)
Article
Physics, Mathematical
Lars Andersson, Thomas Backdahl, Pieter Blue, Siyuan Ma
Summary: This paper introduces and explores a new gauge choice for the vacuum Einstein equation, inspired by the ingoing and outgoing radiation gauges (IRG, ORG) used for the linearized vacuum Einstein equation. Previous research has shown that the IRG/ORG are consistent gauges for the linearized vacuum Einstein equation on Petrov type II backgrounds. The new nonlinear radiation gauge introduced in this paper is a direct generalization of the ORG gauge condition, and is intended for studying the stability of Kerr black holes under the evolution generated by the vacuum Einstein equation.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(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
Meng-He Wu, Hong Guo, Xiao-Mei Kuang
Summary: We investigated the impact of the hairy Kerr spacetimes on the spin of a test gyro and accretion disk. Our analysis showed that the black hole hair suppresses the precession frequencies of the test gyro in comparison with Kerr spacetime in general relativity. Additionally, the frequencies can be used to differentiate the hairy Kerr black hole from the naked singularity. We also examined the quasiperiodic oscillations phenomena as the accretion disk approaches the hairy Kerr black hole or naked singularity and found that the hairy parameters significantly affect the frequencies.
Article
Astronomy & Astrophysics
Sourabh Nampalliwar, Aristomenis I. Yfantis, Kostas D. Kokkotas
Summary: This paper presents the extension of general relativistic magnetohydrodynamic simulations to parametrically deformed black holes, allowing for a better understanding of the disk structure, stability, and radiative efficiency. Fe K alpha profiles are computed and future outlook is discussed.
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
Astronomy & Astrophysics
Ming Zhang, Jie Jiang
Summary: In the extended scalar-tensor-Gauss-Bonnet (ESTGB) field theory, a specific nonminimal coupling between a massless scalar field and the Gauss-Bonnet curvature invariant promotes the tachyonic instability of the Kerr-Newman (KN) black hole. The critical spin and charge for the onset of the spontaneous scalarization phenomenon in the KN black hole are calculated under the infinitely large coupling limit. Furthermore, an analytical formula for the coupling-strength-dependent critical existence line is obtained for the black-hole-scalar-field configuration in the finite large coupling regime. Numerical methods are used to plot threshold curves between bald KN black holes and their hairy counterparts. Interestingly, scalarization of the KN black hole is found to occur in the vanishing spin limit in the ESTGB theory.
Article
Astronomy & Astrophysics
Kris Schroven, Saskia Grunau
Summary: This article investigates the innermost stable circular orbit (ISCO) of electrically charged particles in different spacetimes. The study shows that the radius of the ISCO is affected by the product of the charges of the particle and the black hole, while repulsive and attractive Coulomb interactions can change the characteristics of the ISCO.
Article
Astronomy & Astrophysics
A. Bokulic, I Smolic, T. Juric
Summary: Two theorems have been proven which show that under specific conditions, a nonlinear electromagnetic field must be either trivial or stealth. The first theorem applies to static spacetimes, while the second theorem relies on the positive energy theorem and does not require the spacetime metric to be static.
Article
Astronomy & Astrophysics
Jerzy Lewandowski, Maciej Ossowski
Summary: This paper extends and refines Misner's nonsingular interpretation of Taub-NUT spacetimes proposed in 1969, by utilizing the algebraic structure of Killing vector fields to completely solve the issue of a nonsingular extension of Kerr-NUT-(anti-)de Sitter solutions.
Article
Astronomy & Astrophysics
Przemyslaw Malkiewicz, Artur Miroszewski
Summary: Quantum cosmological models are commonly described using semiclassical approximations, with a focus on the uncertainty in background variables and its impact on primordial gravitational waves. The study reveals two quantum effects from the cosmological background, including a repulsive potential resolving the big bang singularity, and uncertainties in numerical values for background spacetime variables. Through quantization and the WKB approximation, an analytical formula for the amplitude spectrum of gravitational waves is derived.
Article
Astronomy & Astrophysics
Jiri Vesely, Martin Zofka
Summary: The study focused on cylindrically symmetric, static electrovacuum spacetimes generated by a magnetic field, potentially with the inclusion of the cosmological constant. Various classes of exact solutions were explored, all of which were due to magnetic fields perpendicular to the axis of symmetry.
Article
Astronomy & Astrophysics
Rafael F. Aranha, Carlos E. M. Cedeno, Rodrigo Maier, Ivano Damiao Soares
Summary: In this study, the spacetime of a boosted Bondi-Sachs rotating black hole is used as a background to examine electromagnetic configurations connected to analytic solutions of Maxwell equations. The Kerr-Schild form is employed to construct zero angular momentum observers (ZAMOs) and evaluate the components of the electric and magnetic fields. Nonsingular patterns of momentum-energy emission in a boosted Kerr-Schild black hole are investigated with varying boost parameters, extending the analysis to consider electromagnetic emission in the framework of a rotating boosted black hole moving at relativistic speeds. Possible mechanisms resembling magnetospheres of rotating boosted black holes are discussed, including the generation of hydromagnetic flows from accretion discs and the production of jets.
Article
Astronomy & Astrophysics
Ignacio F. Ranea-Sandovaol, Federico Garcia
ASTRONOMY & ASTROPHYSICS
(2015)
Article
Astronomy & Astrophysics
Ignacio F. Ranea-Sandoval, Hector Vucetich
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2015)
Article
Astronomy & Astrophysics
Ignacio F. Ranea-Sandovaol, Federico Garcia
ASTRONOMY & ASTROPHYSICS
(2015)
Article
Astronomy & Astrophysics
Federico Garcia, Ignacio F. Ranea-Sandoval, Tim Johannsen
ASTRONOMY & ASTROPHYSICS
(2016)
Article
Astronomy & Astrophysics
Federico Garcia, Ignacio F. Ranea-Sandoval, Tim Johannsen
ASTRONOMY & ASTROPHYSICS
(2016)
Article
Astronomy & Astrophysics
M. Orsaria, Ignacio F. Ranea-Sandoval, H. Vucetich
ASTROPHYSICAL JOURNAL
(2011)
Article
Astronomy & Astrophysics
Gustavo Dotti, Reinaldo J. Gleiser, Ignacio F. Ranea-Sandoval, Hector Vucetich
CLASSICAL AND QUANTUM GRAVITY
(2008)
Article
Physics, Nuclear
Gustavo Dotti, Reinaldo J. Gleiser, Jorge Pullin, Ignacio F. Ranea-Sandoval, Hector Vucetich
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2009)
Article
Physics, Nuclear
Gustavo Dotti, Reinaldo J. Gleiser
INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS
(2011)
Article
Physics, Nuclear
Ignacio F. Ranea-Sandoval, Milva G. Orsaria, Sophia Han, Fridolin Weber, William M. Spinella
Article
Physics, Nuclear
Ignacio F. Ranea-Sandoval, Sophia Han, Milva G. Orsaria, Gustavo A. Contrera, Fridolin Weber, Mark G. Alford
Article
Astronomy & Astrophysics
Federico Garcia, Ignacio F. Ranea-Sandoval
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2015)