scholarly journals Thermodynamics of de Sitter black holes: Thermal cosmological constant

2006 ◽  
Vol 73 (8) ◽  
Author(s):  
Y. Sekiwa
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
De Sitter

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 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 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 De sitter magnetic black hole dipole with a supersymmetric horizon

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Davide Astesiano ◽  
S.L. Cacciatori
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Cosmological Constant ◽  
The Other ◽  
Gauge Fields ◽  
Positive Pressure ◽  
Closed Universe ◽  
De Sitter ◽  
Extremal Black Holes

Abstract We find a new non BPS solution in N = 2 D = 4 gauged supergravity coupled to U(1) gauge fields and matter. It consists in a closed universe with two extremal black holes of equal size, surrounding two singularities. They have opposite magnetic charges (and no electric charges), but stay in static equilibrium thanks to the positive pressure of a cosmological constant. The geometry is perfectly symmetric under the exchange of the black holes and the flip of the sign of the charges. However the scalar field is non constant and non symmetric, with different values at the horizons, which depend on a real modulus. Remarkably we show that it satisfies the attractor mechanism and the entropy indeed depends only on the magnetic charges. At one of the horizons the solution becomes $$ \frac{1}{2} $$ 1 2 -BPS supersymmetric, while at the other one there is no supersymmetry, but the entropy remains independent from the scalar modulus.

scholarly journals “MODULI SPACE” OF ASYMPTOTICALLY ANTI-DE-SITTER SPACE-TIMES IN 2+1 DIMENSIONS

1995 ◽  
Vol 10 (29) ◽  
pp. 4139-4160 ◽  
Author(s):  
KIYOSHI EZAWA
Keyword(s):  
Black Holes ◽  
General Solution ◽  
Power Series ◽  
Cosmological Constant ◽  
Moduli Space ◽  
Three Dimensional ◽  
Einstein Equations ◽  
Quadratic Differentials ◽  
De Sitter ◽  
Inverse Radius

Setting an ansatz that the metric is expressible by a power series of the inverse radius and taking a particular gauge choice, we construct a “general solution” of (2+1)-dimensional Einstein equations with a negative cosmological constant in the case where the space-time is asymptotically anti-de-Sitter. Our general solution turns out to be parametrized by two centrally extended quadratic differentials on S1. In order to include three-dimensional black holes naturally in our general solution, it is necessary to exclude the region inside the horizon. We also discuss the relation of our general solution to the moduli space of flat [Formula: see text] connections.

scholarly journals NONSINGULAR BLACK HOLES FROM GRAVITY–MATTER-BRANE LAGRANGIANS

2010 ◽  
Vol 25 (08) ◽  
pp. 1571-1596 ◽  
Author(s):  
EDUARDO GUENDELMAN ◽  
ALEXANDER KAGANOVICH ◽  
EMIL NISSIMOV ◽  
SVETLANA PACHEVA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Radial Coordinate ◽  
De Sitter ◽  
Wormhole Solution ◽  
Interior Region ◽  
Exterior Region ◽  
Inner Horizon ◽  
Self Consistent

We consider self-consistent coupling of bulk Einstein–Maxwell–Kalb–Ramond system to codimension-one charged lightlikep-brane with dynamical (variable) tension (LL-brane). The latter is described by a manifestly reparametrization-invariant worldvolume action significantly different from the ordinary Nambu–Goto one. We show that the LL-brane is the appropriate gravitational and charge source in the Einstein–Maxwell–Kalb–Ramond equations of motion needed to generate a self-consistent solution describing nonsingular black hole. The latter consists of de Sitter interior region and exterior Reissner–Nordström region glued together along their common horizon (it is the inner horizon from the Reissner–Nordström side). The matching horizon is automatically occupied by the LL-brane as a result of its worldvolume Lagrangian dynamics, which dynamically generates the cosmological constant in the interior region and uniquely determines the mass and charge parameters of the exterior region. Using similar techniques we construct a self-consistent wormhole solution of Einstein–Maxwell system coupled to electrically neutral LL-brane, which describes two identical copies of a nonsingular black hole region being the exterior Reissner–Nordström region above the inner horizon, glued together along their common horizon (the inner Reissner–Nordström one) occupied by the LL-brane. The corresponding mass and charge parameters of the two black hole "universes" are explicitly determined by the dynamical LL-brane tension. This also provides an explicit example of Misner–Wheeler "charge without charge" phenomenon. Finally, this wormhole solution connecting two nonsingular black holes can be transformed into a special case of Kantowski–Sachs bouncing cosmology solution if instead of Reissner–Nordström we glue together two copies of the exterior Reissner–Nordström–de Sitter region with big enough bare cosmological constant, such that the radial coordinate becomes a timelike variable everywhere in the two "universes," except at the matching hypersurface occupied by the LL-brane.

scholarly journals Quasi-normal modes and stability of Einstein–Born–Infeld black holes in de Sitter space

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Chong Oh Lee ◽  
Jin Young Kim ◽  
Mu-In Park
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Normal Modes ◽  
Extremal Black Hole ◽  
Wkb Method ◽  
De Sitter ◽  
Charged Black Holes ◽  
Resonance Modes ◽  
Metric Functions ◽  
The Stability

Abstract We study gravitational perturbations of electrically charged black holes in (3+1)-dimensional Einstein–Born–Infeld gravity with a positive cosmological constant. For the axial perturbations, we obtain a set of decoupled Schrödinger-type equations, whose formal expressions, in terms of metric functions, are the same as those without cosmological constant, corresponding to the Regge–Wheeler equation in the proper limit. We compute the quasi-normal modes (QNMs) of the decoupled perturbations using the Schutz–Iyer–Will’s WKB method. We discuss the stability of the charged black holes by investigating the dependence of quasi-normal frequencies on the parameters of the theory, correcting some errors in the literature. It is found that all the axial perturbations are stable for the cases where the WKB method applies. There are cases where the conventional WKB method does not apply, like the three-turning-points problem, so that a more generalized formalism is necessary for studying their QNMs and stabilities. We find that, for the degenerate horizons with the “point-like” horizons at the origin, the QNMs are quite long-lived, close to the quasi-resonance modes, in addition to the “frozen” QNMs for the Nariai-type horizons and the usual (short-lived) QNMs for the extremal black hole horizons. This is a genuine effect of the branch which does not have the general relativity limit. We also study the exact solution near the (charged) Nariai limit and find good agreements even far beyond the limit for the imaginary frequency parts.

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.

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