Article
Astronomy & Astrophysics
Joao Paulo Cavalcante, Bruno Carneiro da Cunha
Summary: The study investigates spin perturbations for nonextremal and extremal Reissner-Nordstrom backgrounds using the isomonodromic method. By calculating the fundamental quasinormal modes associated with each perturbation, the study reveals the existence of nondamping modes for qQ above a spin-dependent critical value and determines the bifurcation point in the q - Q parameter space.
Article
Astronomy & Astrophysics
Christiane Klein, Jochen Zahn
Summary: The Hadamard point-split renormalization of the current density of a charged scalar field in a Reissner-Nordstrom-de Sitter spacetime was performed, with numerical computations of the expectation values in the Unruh state in the exterior region. The study examined the dependence on field parameters and position.
Article
Astronomy & Astrophysics
Libo Xie, Chaoxi Fang, Jie Jiang, Ming Zhang
Summary: In this study, we analytically investigate the scalarization of higher-dimensional charged Reissner-Nordstrom black hole. It is found that a static massive scalar field, which is non-minimally coupled to the Gauss-Bonnet invariant, can be supported by the higher-dimensional black hole in the super-critical charge regime. Moreover, we demonstrate that the static massive scalar shell can be incredibly thin in the large mass regime.
Article
Astronomy & Astrophysics
Bo Yang, Chunhua Jiang, Wenbin Lin
Summary: In this study, we derive the second post-Newtonian solution for the quasi-Keplerian motion of a charged test particle in the Reissner-Nordstrom spacetime under harmonic coordinates. The solution is formulated in terms of the test particle's orbital energy and angular momentum, which are both constants at the second post-Newtonian order. We explicitly display the effects of charge on the test particle's motion, including the orbital period and perihelion precession. Our results can be applied to cases where the test particle has a small charge-to-mass ratio or the multiplication of the test particle and the gravitational source's charge-to-mass ratios is much smaller than 1.
Article
Astronomy & Astrophysics
Adolfo Cisterna, Carla Henriquez-Baez, Nicolas Mora, Leonardo Sanhueza
Summary: In this work, consistent compactifications of Einstein-Maxwell and Einstein-Maxwell-Lovelock theories are provided on direct product spacetimes, with specific flux distribution of p-forms over the internal manifold. The dynamics of the p-forms are controlled by interactions with curvature tensor and electromagnetic field, leading to the construction of homogenously charged black p-branes in the corresponding compactified theories.
Article
Astronomy & Astrophysics
Julian Barragan Amado, Bruno Carneiro da Cunha, Elisabetta Pallante
Summary: We investigated the quasinormal modes (QNMs) of a charged scalar field on a Reissner-Nordstrom-anti-de Sitter (RN-AdS(5)) black hole in the small radius limit using the isomonodromic method. We derived the low-temperature expansion of the fundamental QNM frequency and provided numerical evidence of instabilities appearing for large values of the charge of the scalar field in the small radius limit.
Article
Astronomy & Astrophysics
Gustavo Garcia, Marcelo Salgado
Summary: This work reanalyzes the possibility of finding bound states of a charged and complex-valued scalar field in the background of a Reissner-Nordstrom black hole, with numerical evidence and a theorem. It shows that under certain conditions such clouds do not exist, but with the inclusion of a self-interacting potential, there may be charged clouds present.
Article
Astronomy & Astrophysics
R. D. B. Fontana, P. A. Gonzalez, Eleftherios Papantonopoulos, Yerko Vasquez
Summary: The anomalous decay rate behavior of scalar field perturbations in charged spacetimes shows a critical scalar field mass in photon sphere modes. The dominant mode/family for massless and massive scalar fields in these geometries depends on black hole mass and charge. The critical mass value increases with raising black hole charge, with a minimum in the Schwarzschild limit.
Article
Physics, Particles & Fields
Jing Zhang, Yi Xie
Summary: We investigate the weak and strong deflection gravitational lensing by a black-bounce-Reissner-Nordstrom spacetime and compare it with other spacetimes. We find that distinguishing these spacetimes may be possible by measuring the fluxes difference of the lensed images.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
P. A. Gonzalez, Marco Olivares, Yerko Vasquez, J. R. Villanueva
Summary: The study focuses on the motion of photons around a five-dimensional black hole and observational tests such as light bending and time delay effects. It was found that the motion of photons follows a specific type of geodesic, indicating new characteristics in their trajectories.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Jia-Hui Huang, Run-Dong Zhao, Yi-Feng Zou
Summary: The study analytically investigated the superradiant stability of asymptotically flat higher dimensional non-extremal Reissner-Nordstrom black holes under charged massive scalar perturbation. The results suggest that these black holes may exhibit superradiant stability.
Article
Astronomy & Astrophysics
Sanjar Shaymatov, Bakhtiyor Narzilloev, Ahmadjon Abdujabbarov, Cosimo Bambi
Summary: The study investigates the dynamics of neutral and charged test particles around axially symmetric magnetized black hole spacetime, showing that the combined effects of black hole electric charge and magnetic field strongly affect the innermost stable circular orbit radius. The repulsive (attractive) Coulomb force dominates over the Lorentz force from the black hole magnetic field, and increases in black hole magnetic field and electric charge lead to high center of mass energy extracted by the collision of particles. Ultimately, the presence of magnetic field in a magnetized black hole solution results in axially symmetric spacetime.
Article
Astronomy & Astrophysics
Julio Arrechea, Carlos Barcelo, Raul Carballo-Rubio, Luis J. Garay
Summary: The study focuses on the renormalized stress-energy tensor and backreaction of a massless scalar field on the classical Reissner-Nordstrom spacetime. Different geometries are observed depending on the charge-to-mass ratio, including singularities, wormhole necks, and naked singularities. The resulting horizon from the semiclassical backreaction is shown to be singular despite the finite RSET over the extremal horizon.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Run-Dong Zhao, Jia-Hui Huang
Summary: The superradiant stability of higher dimensional non-extremal Reissner-Nordstrom black hole under charged massive scalar perturbation is analytically studied. It is found that there is no potential well outside the outer horizon of the black hole for the superradiant scalar modes, indicating the absence of a black hole bomb and the superradiant stability of the system.
Article
Astronomy & Astrophysics
Theodoros Nakas, Panagiota Kanti
Summary: In this work, a five-dimensional spherically symmetric, charged, and asymptotically anti-de Sitter black hole with a pointlike singularity localized on a brane is constructed. The horizons are shown to be exponentially localized close to the brane with a pancake shape. The effective gravitational equations on the brane reveal that the Reissner-Nordstrom-(A)dS geometry is caused by the combined effect of the five-dimensional geometry and bulk matter.
Article
Astronomy & Astrophysics
Eugeny Babichev, Christos Charmousis, Adolfo Cisterna, Mokhtar Hassaine
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2020)
Article
Physics, Particles & Fields
Eugeny Babichev
JOURNAL OF HIGH ENERGY PHYSICS
(2020)
Article
Astronomy & Astrophysics
Eugeny Babichev, Dmitry Gorbunov, Sabir Ramazanov
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2020)
Review
Astronomy & Astrophysics
Vyacheslav Dokuchaev, Natalia O. Nazarova
Article
Astronomy & Astrophysics
V. A. Berezin, V. Dokuchaev, Yu N. Eroshenko, A. L. Smirnov
Summary: The equations for double layers in quadratic gravity were derived using the least action principle without the use of the δ'-function, instead canceling out the δ-functions during integration. The study revealed that the surface energy-momentum tensor of matter fields does not affect the trajectory of double layers, and suggested that space-like double layers could provide an adequate description of the creation of the Universe from a black hole singularity. Related topics such as the Gauss-Bonnet term and F(R)-theories were briefly discussed.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Physics, Particles & Fields
Timothy Anson, Eugeny Babichev, Christos Charmousis, Mokhtar Hassaine
Summary: This study analytically constructs disformal versions of the Kerr spacetime with scalar hair in a higher order scalar tensor theory, finding that the resulting metric is not Ricci flat, not circular, and has a ring singularity. Approaching the rotating compact object reveals differences in the stationary limit ergosurface and the event horizon compared to the traditional Kerr solution. The disformed Kerr metric is therefore identified as a black hole distinct from the standard Kerr solution.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Vyacheslav Dokuchaev, Natalia O. Nazarova
Summary: We study the general relativistic motion of a bright spot in a jet from an accreting black hole, calculating the corresponding lens images numerically in discrete time intervals. Observations of moving bright spots in black hole jets provide a unique opportunity to verify different gravitational theories in the strong field limit.
GENERAL RELATIVITY AND GRAVITATION
(2021)
Article
Astronomy & Astrophysics
V. A. Berezin, V. I. Dokuchaev, Yu. N. Eroshenko, A. L. Smirnov
Summary: This study investigates the construction of homogeneous and isotropic cosmological solutions in Weyl geometry, deriving a self-consistency condition for conformal invariance. Special solutions are found when the Weyl vector equals zero, leading to new vacuum cosmological solutions not present in General Relativity. Additionally, a new solution for a radiation dominated universe with a cosmological term is discovered, potentially relating to our understanding of dark matter and dark energy.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
E. Babichev, D. Gorbunov, S. Ramazanov, A. Vikman
Summary: Cosmic domain walls are harmless if their tension decreases with the expansion of the Universe. The tension can be large in the early Universe without conflicting observations if it is induced dynamically through interaction with hot primordial plasma. These topological defects can serve as a powerful source of gravitational waves due to their large initial tension.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
V. A. Berezin, V. Dokuchaev
Summary: This study investigates the possibility of homogeneous and isotropic cosmological solutions in Weyl geometry. By introducing the Weyl vector and constructing a gravitational Lagrangian that is quadratic in curvatures and conformal invariant, Weyl gravity is obtained. It is found that a solution can exist if there is a direct interaction between the Weyl vector and matter fields. Assuming matter is a perfect fluid, the study explores how this interaction can be realized and determines the rate of particle production, which is found to be conformal invariant. Furthermore, the study examines the persistence of the vacuum state in the case of creating the Universe 'from nothing,' showing that the vacuum can persist in producing non-dust matter but not dust particles, which may serve as candidates for dark matter.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Eugeny Babichev, Christos Charmousis, Mokhtar Hassaine, Nicolas Lecoeur
Summary: In arbitrary higher dimension, we consider the combination of Lovelock gravity and a scalar-tensor action built out of higher order operators and Euler densities. The existence of black hole solutions interpreted as stealth configurations within Lovelock gravity theory is shown. The stealth solutions can include a time-dependent scalar field despite the underlying theory being non shift symmetric. Also, a procedure to obtain a nonconformally invariant action in even dimensions from the considered theory is presented.
Article
Astronomy & Astrophysics
Eugeny Babichev, Christos Charmousis, Mokhtar Hassaine, Nicolas Lecoeur
Summary: This article studies a higher order conformally coupled scalar tensor theory with a covariant geometric constraint that relates the scalar curvature to the Gauss-Bonnet scalar. The properties of an asymptotically flat spherically symmetric black hole are analyzed, and new slowly rotating and radiating extensions are found. Gravitating monopolelike solutions and eternal wormholes are presented through disformal transformations of the static configurations.
Article
Astronomy & Astrophysics
S. Ramazanov, E. Babichev, D. Gorbunov, A. Vikman
Summary: This study proposes a novel scenario for the production of dark matter that is naturally connected with the generation of gravitational waves. The model describes dark matter as a real scalar that interacts with the hot primordial plasma through a coupling to another scalar field. The model predicts the formation of domain walls in the Universe, which emit gravitational waves with characteristics determined by those of dark matter.
Article
Physics, Multidisciplinary
Victor A. Berezin, Vyacheslav I. Dokuchaev
Summary: This paper discusses conformal invariant gravitation based on Weyl geometry, introducing the interaction between the Weyl vector and the vector representing the world line of the independent observer. It is found that this interaction leads to the selection of exponentially growing scale factor solutions in cosmological vacua.
Article
Astronomy & Astrophysics
T. Anson, E. Babichev, C. Charmousis
Summary: We analyze the post-Newtonian orbit of stars around a deformed Kerr black hole and show that for generic nonzero D, the no-hair theorem of general relativity is violated.
