scholarly journals Perturbations in the Kerr-Newman dilatonic black hole background: Maxwell waves, the dilaton background, and gravitational lensing

1998 ◽  
Vol 58 (4) ◽  
Author(s):  
R. Casadio ◽  
B. Harms
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Black Hole Background ◽  
Dilatonic Black Hole

scholarly journals Entropy in Dilatonic Black Hole Background

1994 ◽  
Vol 73 (19) ◽  
pp. 2521-2523 ◽  
Author(s):  
A. Ghosh ◽  
P. Mitra
Keyword(s):  
Black Hole ◽  
Black Hole Background ◽  
Dilatonic Black Hole

scholarly journals HAWKING RADIATION FOR SCALAR AND DIRAC FIELDS IN FIVE-DIMENSIONAL DILATONIC BLACK HOLE VIA ANOMALIES

2012 ◽  
Vol 21 (03) ◽  
pp. 1250030 ◽  
Author(s):  
RAMÓN BECAR ◽  
P. A. GONZÁLEZ
Keyword(s):  
Black Hole ◽  
Gauge Invariance ◽  
Scalar Fields ◽  
Two Dimensional ◽  
Massive Scalar ◽  
Dimensional Theory ◽  
Dirac Fields ◽  
Black Hole Background ◽  
Planck Distribution ◽  
Dilatonic Black Hole

We study massive scalar fields and Dirac fields propagating in a five-dimensional dilatonic black hole background. We expose that for both fields the physics can be described by a two-dimensional theory, near the horizon. Then, in this limit, by applying the covariant anomalies method we find the Hawking flux by restoring the gauge invariance and the general coordinate covariance, which coincides with the flux obtained from integrating the Planck distribution for fermions.

THE FERMIONIC ENTROPY IN DILATONIC BLACK HOLE BACKGROUND SPACETIME

2001 ◽  
Vol 10 (04) ◽  
pp. 539-546 ◽  
Author(s):  
YOU-GEN SHEN ◽  
DA-MING CHEN
Keyword(s):  
Black Hole ◽  
Free Energy ◽  
Brick Wall ◽  
Wall Model ◽  
Brick Wall Model ◽  
Black Hole Background ◽  
Back Ground ◽  
Dilatonic Black Hole ◽  
Fermionic Entropy

The fermionic free energy and entropy are calculated in Garfinkle–Horowitz–Strominger dilatonic black hole background spacetime, by using 't Hfoot's brick wall model. It turns out that the fermionic entropy in Garfinkle–Horowitz–Strominger dilatonic black hole back ground spacetime is 7/2 times the Bosonic entropy.

scholarly journals Null Geodesics and Gravitational Lensing in a Nonsingular Spacetime

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Shao-Wen Wei ◽  
Yu-Xiao Liu ◽  
Chun-E Fu
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Angular Position ◽  
Angular Separation ◽  
Null Geodesics ◽  
Astronomical Instruments ◽  
Black Hole Background ◽  
Deflection Limit ◽  
Near Future

The null geodesics and gravitational lensing in a nonsingular spacetime are investigated. According to the nature of the null geodesics, the spacetime is divided into several cases. In the weak deflection limit, we find the influence of the nonsingularity parameterqon the positions and magnifications of the images is negligible. In the strong deflection limit, the coefficients and observables for the gravitational lensing in a nonsingular black hole background and a weakly nonsingular spacetime are obtained. Comparing these results, we find that, in a weakly nonsingular spacetime, the relativistic images have smaller angular position and relative magnification but larger angular separation than those of a nonsingular black hole. These results might offer a way to probe the spacetime nonsingularity parameter and put a bound on it by the astronomical instruments in the near future.

scholarly journals Perturbations in the Kerr-Newman dilatonic black hole background: Maxwell waves

1997 ◽  
Vol 56 (8) ◽  
pp. 4948-4961 ◽  
Author(s):  
R. Casadio ◽  
B. Harms ◽  
Y. Leblanc ◽  
P. H. Cox
Keyword(s):  
Black Hole ◽  
Black Hole Background ◽  
Dilatonic Black Hole

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 Normal-mode analysis for scalar fields in BTZ black-hole background

2009 ◽  
Vol 60 (2) ◽  
pp. 169-173 ◽  
Author(s):  
Sayan K. Chakrabarti ◽  
Pulak Ranjan Giri ◽  
Kumar S. Gupta
Keyword(s):  
Black Hole ◽  
Normal Mode ◽  
Normal Mode Analysis ◽  
Scalar Fields ◽  
Mode Analysis ◽  
Btz Black Hole ◽  
Black Hole Background

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.

scholarly journals Gravitational Lensing in Presence of Plasma: Strong Lens Systems, Black Hole Lensing and Shadow

Universe ◽  
2017 ◽  
Vol 3 (3) ◽  
pp. 57 ◽  
Author(s):  
Gennady Bisnovatyi-Kogan ◽  
Oleg Tsupko
Keyword(s):  
Black Hole ◽  
Gravitational Lensing
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