scholarly journals Pure Gauss–Bonnet NUT black hole with and without non-central singularity

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Sajal Mukherjee ◽  
Naresh Dadhich
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Higher Dimensions ◽  
Radial Symmetry ◽  
Cosmological Horizon ◽  
Vacuum Equation ◽  
Closed Timelike Curves ◽  
Central Singularity ◽  
Horizon Topology ◽  
Nut Solution

AbstractIt is known that NUT solution has many interesting features and pathologies like being non-singular and having closed timelike curves. It turns out that in higher dimensions horizon topology cannot be spherical but it has instead to be product of 2-spheres so as to retain radial symmetry of spacetime. In this letter we wish to present a new solution of pure Gauss–Bonnet $$\Lambda $$ Λ -vacuum equation describing a black hole with NUT charge. It has three interesting cases: (a) black hole with both event and cosmological horizons with singularity being hidden behind the former, (b) a regular spacetime free of both horizon and singularity, and (c) black hole with event horizon without singularity and cosmological horizon. Singularity here is always non-centric at $$r \ne 0$$ r ≠ 0 .

scholarly journals LUKEWARM BLACK HOLES IN QUADRATIC GRAVITY

2011 ◽  
Vol 26 (14) ◽  
pp. 999-1007 ◽  
Author(s):  
JERZY MATYJASEK ◽  
KATARZYNA ZWIERZCHOWSKA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Fourth Order ◽  
Spherically Symmetric ◽  
Cosmological Horizon ◽  
De Sitter ◽  
Quadratic Gravity ◽  
De Sitter Universe ◽  
Electrically Charged

Perturbative solutions to the fourth-order gravity describing spherically-symmetric, static and electrically charged black hole in an asymptotically de Sitter universe is constructed and discussed. Special emphasis is put on the lukewarm configurations, in which the temperature of the event horizon equals the temperature of the cosmological horizon.

scholarly journals On the duality of Schwarzschild-de Sitter spacetime and moving mirror

2022 ◽  
Author(s):  
Diego Fernández-Silvestre ◽  
Joshua Foo ◽  
Michael R.R Good
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Simple Solution ◽  
Particle Spectrum ◽  
Cosmological Horizon ◽  
De Sitter ◽  
Einstein’S Equations ◽  
Relative Temperature ◽  
Einstein's Equations ◽  
Sitter Spacetime

Abstract The Schwarzschild-de Sitter (SdS) metric is the simplest spacetime solution in general relativity with both a black hole event horizon and a cosmological event horizon. Since the Schwarzschild metric is the most simple solution of Einstein's equations with spherical symmetry and the de Sitter metric is the most simple solution of Einstein's equations with a positive cosmological constant, the combination in the SdS metric defines an appropriate background geometry for semi-classical investigation of Hawking radiation with respect to past and future horizons. Generally, the black hole temperature is larger than that of the cosmological horizon, so there is heat flow from the smaller black hole horizon to the larger cosmological horizon, despite questions concerning the definition of the relative temperature of the black hole without a measurement by an observer sitting in an asymptotically flat spacetime. Here we investigate the accelerating boundary correspondence (ABC) of the radiation in SdS spacetime without such a problem. We have solved for the boundary dynamics, energy flux and asymptotic particle spectrum. The distribution of particles is globally non-thermal while asymptotically the radiation reaches equilibrium.

scholarly journals Generalized second law and universal relations of cosmological black hole

2019 ◽  
Vol 9 (2) ◽  
pp. 281-288
Author(s):  
Ashfaque H. Bokhari ◽  
M. Akbar ◽  
Tayeb Brahimi
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Cosmological Horizon ◽  
Generalized Second Law ◽  
Area Product ◽  
Mass Dependent ◽  
Product Relation

Abstract The objective of this paper is to investigate the validity conditions for the generalized second law of thermodynamics, and the universal relations for multi-horizon dynamical spacetime. It is found that there are three horizons of McVittie universe termed as event horizon, cosmological apparent horizon, and virtual horizon. The mass-dependent and mass-independent area product relations are formulated in terms of areas of the dynamical event horizon, cosmological horizon and virtual horizon. It is noted that whereas the area sum relation is mass independent, the area product relation is explicitly mass dependent. Moreover, we have also analyzed and listed explicit mass-independent and mass-dependent relations.

scholarly journals Towards an observational test of black hole versus naked singularity at the galactic center

2019 ◽  
Vol 28 (14) ◽  
pp. 1930024 ◽  
Author(s):  
Dipanjan Dey ◽  
Pankaj S. Joshi ◽  
Ashok Joshi ◽  
Parth Bambhaniya
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Galactic Center ◽  
Naked Singularity ◽  
Compact Object ◽  
Central Singularity ◽  
Recent Developments ◽  
Clear Idea ◽  
Theoretical Results

While the event horizon of a black hole could cast a shadow that was observed recently, a central singularity without horizon could also give rise to such a feature. This leaves us with a question on the nature of the supermassive black holes at the galactic centers, and if they admit an event horizon necessarily. We point out that observations of motion of stars around the galactic center should give a clear idea of the nature of this central supermassive object. We examine and discuss here recent developments that indicate intriguing behavior of the star motions that could possibly distinguish the existence or otherwise of an event horizon at the galactic center. We compare the motion of the S2 star with these theoretical results, fitting the observational data with theory, and it is seen that the star motions and precession of their orbits around the galactic center provide important clues on the nature of this central compact object.

scholarly journals No Way Back: Maximizing Survival Time Below the Schwarzschild Event Horizon

2007 ◽  
Vol 24 (2) ◽  
pp. 46-52 ◽  
Author(s):  
Geraint F. Lewis ◽  
Juliana Kwan
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Survival Time ◽  
Event Horizon ◽  
Proper Time ◽  
Teaching Tool ◽  
Maximum Value ◽  
Central Singularity ◽  
Remaining Time

AbstractIt has long been known that once you cross the event horizon of a black hole, your destiny lies at the central singularity, irrespective of what you do. Furthermore, your demise will occur in a finite amount of proper time. In this paper, the use of rockets in extending the amount of time before the collision with the central singularity is examined. In general, the use of such rockets can increase your remaining time, but only up to a maximum value; this is at odds with the ‘more you struggle, the less time you have' statement that is sometimes discussed in relation to black holes. The derived equations are simple to solve numerically and the framework can be employed as a teaching tool for general relativity.

scholarly journals Correlation functions in finite temperature CFT and black hole singularities

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
D. Rodriguez-Gomez ◽  
J.G. Russo
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Correlation Functions ◽  
Finite Temperature ◽  
Proper Time ◽  
Black Brane ◽  
Point Function ◽  
Black Hole Singularity ◽  
Point Correlation ◽  
Scaling Dimension

Abstract We compute thermal 2-point correlation functions in the black brane AdS5 background dual to 4d CFT’s at finite temperature for operators of large scaling dimension. We find a formula that matches the expected structure of the OPE. It exhibits an exponentiation property, whose origin we explain. We also compute the first correction to the two-point function due to graviton emission, which encodes the proper time from the event horizon to the black hole singularity.

OBSERVATIONAL CONSTRAINTS ON STRONG GRAVITY

2011 ◽  
Vol 20 (14) ◽  
pp. 2755-2760
Author(s):  
CHRIS DONE
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Strong Field ◽  
Field Tests ◽  
High Energy ◽  
Observational Constraints ◽  
Tests Of General Relativity ◽  
Strong Gravity ◽  
Accretion Flows ◽  
Spacetime Curvature

Accretion onto a black hole transforms the darkest objects in the universe to the brightest. The high energy radiation emitted from the accretion flow before it disappears forever below the event horizon lights up the regions of strong spacetime curvature close to the black hole, enabling strong field tests of General Relativity. I review the observational constraints on strong gravity from such accretion flows, and show how the data strongly support the existence of such fundamental General Relativistic features of a last stable orbit and the event horizon. However, these successes also imply that gravity does not differ significantly from Einstein's predictions above the event horizon, so any new theory of quantum gravity will be very difficult to test.

scholarly journals Black Hole Interior from Loop Quantum Gravity

2008 ◽  
Vol 2008 ◽  
pp. 1-12 ◽  
Author(s):  
Leonardo Modesto
Keyword(s):  
Black Hole ◽  
Quantum Gravity ◽  
Event Horizon ◽  
Loop Quantum Gravity ◽  
Planck Scale ◽  
Semiclassical Analysis ◽  
Schwarzschild Solution ◽  
Quantum Black Hole ◽  
Minimum Value ◽  
Black Hole Interior

We calculate modifications to the Schwarzschild solution by using a semiclassical analysis of loop quantum black hole. We obtain a metric inside the event horizon that coincides with the Schwarzschild solution near the horizon but that is substantially different at the Planck scale. In particular, we obtain a bounce of theS2sphere for a minimum value of the radius and that it is possible to have another event horizon close to ther=0point.

scholarly journals THE MILNE SPACETIME AND THE HADRONIC RINDLER HORIZON

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1379-1384 ◽  
Author(s):  
H. CULETU
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Time Dependent ◽  
Anisotropic Fluid ◽  
Direct Relation ◽  
Schwarzschild Black Hole ◽  
Black Hole Interior ◽  
Flat Metric ◽  
Shear Tensor ◽  
Hadronic Rindler Horizon

A direct relation between the time-dependent Milne geometry and the Rindler spacetime is shown. Milne's metric corresponds to the region beyond Rindler's event horizon (in the wedge t ≻ |x|). We point out that inside a Schwarzschild black hole and near its horizon, the metric may be Milne's flat metric. It was found that the shear tensor associated to a congruence of fluid particles of the RHIC expanding fireball has the same structure as that corresponding to the anisotropic fluid from the black hole interior, even though the latter geometry is curved.

Sign in / Sign up

Export Citation Format

Share Document