scholarly journals Photon regions and shadows of accelerated black holes

2015 ◽  
Vol 24 (09) ◽  
pp. 1542024 ◽  
Author(s):  
Arne Grenzebach ◽  
Volker Perlick ◽  
Claus Lämmerzahl
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Boundary Curve ◽  
Kerr Metric ◽  
Axially Symmetric ◽  
De Sitter ◽  
Acceleration Parameter ◽  
Type D ◽  
Analytical Formulas ◽  
Photon Regions

In an earlier paper, we have analytically determined the photon regions and the shadows of black holes of the Plebański class of metrics which are also known as the Kerr–Newman–NUT–(anti-)de Sitter metrics. These metrics are characterized by six parameters: Mass, spin, electric and magnetic charges, gravitomagnetic NUT charge and the cosmological constant. Here, we extend this analysis to the Plebański–Demiański class of metrics which contains, in addition to these six parameters, the so-called acceleration parameter. All these metrics are axially symmetric and stationary type D solutions to the Einstein–Maxwell equations with a cosmological constant. We derive analytical formulas for the photon regions (i.e. for the regions that contain spherical lightlike geodesics) and for the boundary curve of the shadow as it is seen by an observer at Boyer–Lindquist coordinates (rO, ϑO) in the domain of outer communication. Whereas all relevant formulas are derived for the whole Plebański–Demiański class, we concentrate on the accelerated Kerr metric (i.e. only mass, spin and acceleration parameter are different from zero) when discussing the influence of the acceleration parameter on the photon region and on the shadow in terms of pictures. The accelerated Kerr metric is also known as the rotating C-metric. We discuss how our analytical formulas can be used for calculating the horizontal and vertical angular diameters of the shadow and we estimate these values for the black holes at the center of our Galaxy and at the center of M87.

scholarly journals Axial Symmetry Cosmological Constant Vacuum Solution of Field Equations with a Curvature Singularity, Closed Time-Like Curves, and Deviation of Geodesics

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Faizuddin Ahmed ◽  
Bidyut Bikash Hazarika ◽  
Debojit Sarma
Keyword(s):  
Cosmological Constant ◽  
Vacuum Solution ◽  
Space Time ◽  
Axially Symmetric ◽  
De Sitter ◽  
Curvature Singularity ◽  
Field Equations ◽  
Type D ◽  
Initial Space ◽  
Coulomb Type

In this paper, we present a type D, nonvanishing cosmological constant, vacuum solution of Einstein’s field equations, extension of an axially symmetric, asymptotically flat vacuum metric with a curvature singularity. The space-time admits closed time-like curves (CTCs) that appear after a certain instant of time from an initial space-like hypersurface, indicating it represents a time-machine space-time. We wish to discuss the physical properties and show that this solution can be interpreted as gravitational waves of Coulomb-type propagate on anti-de Sitter space backgrounds. Our treatment focuses on the analysis of the equation of geodesic deviations.

scholarly journals Extremal Cosmological Black Holes in Horndeski Gravity and the Anti-Evaporation Regime

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 210
Author(s):  
Ismael Ayuso ◽  
Diego Sáez-Chillón Gómez
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Linear Order ◽  
Scalar Tensor Theory ◽  
De Sitter ◽  
Tensor Theory ◽  
Effective Cosmological Constant ◽  
Cosmological Black Holes ◽  
Extremal Black Holes

Extremal cosmological black holes are analysed in the framework of the most general second order scalar-tensor theory, the so-called Horndeski gravity. Such extremal black holes are a particular case of Schwarzschild-De Sitter black holes that arises when the black hole horizon and the cosmological one coincide. Such metric is induced by a particular value of the effective cosmological constant and is known as Nariai spacetime. The existence of this type of solutions is studied when considering the Horndeski Lagrangian and its stability is analysed, where the so-called anti-evaporation regime is studied. Contrary to other frameworks, the radius of the horizon remains stable for some cases of the Horndeski Lagrangian when considering perturbations at linear order.

scholarly journals Dynamics of Electromagnetic Fields and Structure of Regular Rotating Electrically Charged Black Holes and Solitons in Nonlinear Electrodynamics Minimally Coupled to Gravity

Universe ◽  
2019 ◽  
Vol 5 (10) ◽  
pp. 205 ◽  
Author(s):  
Irina Dymnikova ◽  
Evgeny Galaktionov
Keyword(s):  
Black Holes ◽  
Electromagnetic Fields ◽  
Nonlinear Electrodynamics ◽  
Axially Symmetric ◽  
De Sitter ◽  
Dynamical Equations ◽  
Naked Singularities ◽  
Charged Black Holes ◽  
De Sitter Vacuum ◽  
Electrically Charged

We study the dynamics of electromagnetic fields of regular rotating electrically charged black holes and solitons replacing naked singularities in nonlinear electrodynamics minimally coupled to gravity (NED-GR). They are related by electromagnetic and gravitational interactions and described by the axially symmetric NED-GR solutions asymptotically Kerr-Newman for a distant observer. Geometry is described by the metrics of the Kerr-Schild class specified by T t t = T r r ( p r = − ρ ) in the co-rotating frame. All regular axially symmetric solutions obtained from spherical solutions with the Newman-Janis algorithm belong to this class. The basic generic feature of all regular objects of this class, both electrically charged and electrically neutral, is the existence of two kinds of de Sitter vacuum interiors. We analyze the regular solutions to dynamical equations for electromagnetic fields and show which kind of a regular interior is favored by electromagnetic dynamics for NED-GR objects.

scholarly journals Fermions tunneling from charged anti-de Sitter black holes

2012 ◽  
Vol 90 (9) ◽  
pp. 903-909 ◽  
Author(s):  
Muhammad Sharif ◽  
Wajiha Javed
Keyword(s):  
Black Holes ◽  
Dirac Equation ◽  
Cosmological Constant ◽  
Hawking Radiation ◽  
Charged Particles ◽  
De Sitter ◽  
Event Horizons ◽  
Horizon Radius ◽  
Fermions Tunneling ◽  
Dilaton Black Holes

We study Hawking radiation as a phenomenon of tunneling through event horizons of charged torus-like as well as dilaton black holes involving a cosmological constant based on Kerner and Mann’s formulation. We obtain tunneling probabilities as well as Hawking’s emission temperature of outgoing charged particles by applying the semiclassical Wentzel–Kramers–Brillouin approximation to the general covariant Dirac equation. The graphical behavior of Hawking temperature and horizon radius is investigated. We find results consistent with those already given in the literature.

scholarly journals Photon regions and shadows of Kerr-Newman-NUT black holes with a cosmological constant

2014 ◽  
Vol 89 (12) ◽  
Author(s):  
Arne Grenzebach ◽  
Volker Perlick ◽  
Claus Lämmerzahl
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Photon Regions

scholarly journals Critical Phenomena of Charged AdS Black Holes in Rastall Gravity

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
De-Cheng Zou ◽  
Ming Zhang ◽  
Chao Wu ◽  
Rui-Hong Yue
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Phase Transitions ◽  
Cosmological Constant ◽  
De Sitter ◽  
Perfect Fluids ◽  
Large Black Hole ◽  
Ads Black Holes ◽  
Phantom Fields

We construct analytical charged anti-de Sitter (AdS) black holes surrounded by perfect fluids in four dimensional Rastall gravity. Then, we discuss the thermodynamics and phase transitions of charged AdS black holes immersed in regular matter like dust and radiation, or exotic matter like quintessence, ΛCDM type, and phantom fields. Surrounded by phantom field, the charged AdS black hole demonstrates a new phenomenon of reentrant phase transition (RPT) when the parameters Q, Np, and ψ satisfy some certain condition, along with the usual small/large black hole (SBH/LBH) phase transition for the surrounding dust, radiation, quintessence, and cosmological constant fields.

Cosmological constant effect on charged and rotating black hole shadows

2021 ◽  
pp. 2150188
Author(s):  
A. Belhaj ◽  
M. Benali ◽  
A. El Balali ◽  
W. El Hadri ◽  
H. El Moumni
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Moduli Space ◽  
Emission Rate ◽  
De Sitter ◽  
Naked Singularities ◽  
Rotating Black Holes ◽  
Rotation Parameters ◽  
Made In

Motivated by recent astrophysical observations, we investigate the shadow behaviors of four-dimensional charged rotating black holes with a cosmological constant. This study is made in terms of a reduced moduli space parameterized by the charge and the rotation parameters. For fixed observers, we analyse in some details the shadow behaviors and the corresponding naked singularities of Kerr–Newman and Kerr–Sen four-dimensional black holes in Anti-de Sitter backgrounds. Then, a comparative discussion is provided by computing the geometrical observables and the energy emission rate.

THERMODYNAMICS OF de SITTER SPACE–TIME IN YORK'S FORMALISM

2001 ◽  
Vol 16 (23) ◽  
pp. 1487-1492 ◽  
Author(s):  
BO-BO WANG ◽  
CHAO-GUANG HUANG
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Path Integral ◽  
De Sitter Space ◽  
Space Time ◽  
Integral Approach ◽  
De Sitter ◽  
First Law Of Thermodynamics ◽  
Path Integral Approach ◽  
Thermodynamics Of Black Holes

The York's formalism of path-integral approach to the thermodynamics of black holes is applied to de Sitter space–time. The first law of thermodynamics for de Sitter space–time is given, which includes a "work term" with respect to the cosmological constant.

scholarly journals Regular Bardeen Black Holes in Anti-de Sitter Spacetime versus Kerr Black Holes through Particle Dynamics

Galaxies ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 63
Author(s):  
Bakhtiyor Narzilloev ◽  
Javlon Rayimbaev ◽  
Ahmadjon Abdujabbarov ◽  
Bobomurat Ahmedov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Magnetic Charge ◽  
Particle Dynamics ◽  
Kerr Metric ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Sitter Spacetime ◽  
Test Particles ◽  
Charge Parameter

In this work, test particle dynamics around a static regular Bardeen black hole (BH) in Anti-de Sitter spacetime has been studied. It has been shown for neutral test particles that parameters of a regular Bardeen black hole in Anti-de Sitter spacetime can mimic the rotation parameter of the Kerr metric up to the value a≈0.9 providing the same innermost stable circular orbit (ISCO) radius. We have also explored the dynamics of magnetized particles with a magnetic dipole moment around a magnetically charged regular Bardeen black hole in Anti-de Sitter spacetime. As a realistic astrophysical scenario of the study, we have treated neutron stars orbiting a supermassive black hole (SMBH), in particular, the magnetar PSR J1745-2900 orbiting Sgr A* with the parameter β=10.2, as magnetized test particles. The magnetized particles dynamics shows that the parameter β, negative values of cosmological constant and magnetic charge parameter of the central BH cause a decrease in the ISCO radius. We have compared the effects of the magnetic charge of the Bardeen BH with the spin of rotating Kerr BH and shown that magnetic charge parameter can mimic the spin in the range a/M≃(0,0.7896) when Λ=0 at the range of its values g/M≃(0,0.648).

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