scholarly journals Entropy Product Formula for Gravitational Instanton

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Parthapratim Pradhan
Keyword(s):  
Black Hole ◽  
Product Formula ◽  
Schwarzschild Black Hole ◽  
Gravitational Instantons ◽  
Gravitational Instanton ◽  
Entropy Product ◽  
Independent Features

We investigate the entropy product formula for various gravitational instantons. We speculate that due to the mass-independent features of the said instatons they are universal as well as quantized. For isolated Euclidean Schwarzschild black hole, these properties simply fail.

scholarly journals Entropy product formula for a spinning BTZ black hole

JETP Letters ◽  
2015 ◽  
Vol 102 (7) ◽  
pp. 427-431 ◽  
Author(s):  
P. Pradhan
Keyword(s):  
Black Hole ◽  
Product Formula ◽  
Btz Black Hole ◽  
Entropy Product

scholarly journals Area (or entropy) product formula for a regular black hole

2016 ◽  
Vol 48 (2) ◽  
Author(s):  
Parthapratim Pradhan
Keyword(s):  
Black Hole ◽  
Product Formula ◽  
Regular Black Hole ◽  
Entropy Product

scholarly journals CFT and Logarithmic Corrections to the Black Hole Entropy Product Formula

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Parthapratim Pradhan
Keyword(s):  
Field Theory ◽  
Black Hole ◽  
Thermal Equilibrium ◽  
Black Hole Entropy ◽  
Quantum Fluctuations ◽  
Product Formula ◽  
Conformal Field ◽  
Inner Horizon ◽  
Logarithmic Corrections ◽  
Entropy Product

We examine the logarithmic corrections to the black hole (BH) entropy product formula of outer horizon and inner horizon by taking into account the effects of statistical quantum fluctuations around the thermal equilibrium and via conformal field theory (CFT). We argue that, in logarithmic corrections to the BH entropy product formula when calculated using CFT and taking into account the effects of quantum fluctuations around the thermal equilibrium, the formula should not be universal and it also should not be quantized. These results have been explicitly checked by giving several examples.

scholarly journals Horizon Areas and Logarithmic Correction to the Charged Accelerating Black Hole Entropy

Universe ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 57 ◽  
Author(s):  
Parthapratim Pradhan
Keyword(s):  
Black Hole ◽  
Black Hole Entropy ◽  
Product Formula ◽  
Logarithmic Correction ◽  
Statistical Fluctuations ◽  
Inner Horizon ◽  
Logarithmic Corrections ◽  
Entropy Product ◽  
Geometric Product ◽  
Area Product

It has been shown by explicit and exact calculation that the geometric product formula i.e., area (or entropy) product formula of outer horizon ( H + ) and inner horizon ( H - ) for charged accelerating black hole (BH) should neither be mass-independent nor quantized. This implies that the area (or entropy ) product is mass-independent conjecture has been broken down for charged accelerating BH. This also further implies that the mass-independent feature of the area product of H ± is not a generic feature at all. We also compute the Cosmic-Censorship-Inequality for this BH. Moreover, we compute the specific heat for this BH to determine the local thermodynamic stability. Under certain criterion, the BH shows the second order phase transition. Furthermore, we compute logarithmic corrections to the entropy for the said BH due to small statistical fluctuations around the thermal equilibrium.

The Schwarzschild black hole

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Black Hole ◽  
Gravitational Field ◽  
Equilibrium Configuration ◽  
Original Form ◽  
Schwarzschild Black Hole ◽  
Schwarzschild Metric ◽  
Schwarzschild Geometry

This chapter discusses the Schwarzschild black hole. It demonstrates how, by a judicious change of coordinates, it is possible to eliminate the singularity of the Schwarzschild metric and reveal a spacetime that is much larger, like that of a black hole. At the end of its thermonuclear evolution, a star collapses and, if it is sufficiently massive, does not become stabilized in a new equilibrium configuration. The Schwarzschild geometry must therefore represent the gravitational field of such an object up to r = 0. This being said, the Schwarzschild metric in its original form is singular, not only at r = 0 where the curvature diverges, but also at r = 2m, a surface which is crossed by geodesics.

Strong Gravitational Lensing for the Quantum-Modified Schwarzschild Black Hole

2021 ◽  
Vol 60 (1) ◽  
pp. 387-396
Author(s):  
Ruanjing Zhang ◽  
Jian Lin ◽  
Qihong Huang
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Schwarzschild Black Hole ◽  
Strong Gravitational Lensing

scholarly journals Black hole S-matrix for a scalar field

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Panos Betzios ◽  
Nava Gaddam ◽  
Olga Papadoulaki
Keyword(s):  
Black Hole ◽  
Normal Modes ◽  
Massless Scalar ◽  
Scattering Process ◽  
Schwarzschild Black Hole ◽  
Asymptotically Flat ◽  
Scalar Particles ◽  
Black Hole Background ◽  
S Matrix ◽  
Do So

Abstract We describe a unitary scattering process, as observed from spatial infinity, of massless scalar particles on an asymptotically flat Schwarzschild black hole background. In order to do so, we split the problem in two different regimes governing the dynamics of the scattering process. The first describes the evolution of the modes in the region away from the horizon and can be analysed in terms of the effective Regge-Wheeler potential. In the near horizon region, where the Regge-Wheeler potential becomes insignificant, the WKB geometric optics approximation of Hawking’s is replaced by the near-horizon gravitational scattering matrix that captures non-perturbative soft graviton exchanges near the horizon. We perform an appropriate matching for the scattering solutions of these two dynamical problems and compute the resulting Bogoliubov relations, that combines both dynamics. This allows us to formulate an S-matrix for the scattering process that is manifestly unitary. We discuss the analogue of the (quasi)-normal modes in this setup and the emergence of gravitational echoes that follow an original burst of radiation as the excited black hole relaxes to equilibrium.

scholarly journals Null Geodesics and Strong Field Gravitational Lensing in a String Cloud Background

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
M. Sharif ◽  
Sehrish Iftikhar
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Galactic Center ◽  
Deflection Angle ◽  
Orbital Motion ◽  
Strong Field ◽  
Schwarzschild Black Hole ◽  
Field Limit ◽  
Null Geodesics ◽  
Supermassive Black Hole

This paper is devoted to studying two interesting issues of a black hole with string cloud background. Firstly, we investigate null geodesics and find unstable orbital motion of particles. Secondly, we calculate deflection angle in strong field limit. We then find positions, magnifications, and observables of relativistic images for supermassive black hole at the galactic center. We conclude that string parameter highly affects the lensing process and results turn out to be quite different from the Schwarzschild black hole.

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