scholarly journals Shadow of a Kerr-like black hole

2014 ◽  
Vol 10 (S312) ◽  
pp. 135-136
Author(s):  
Farruh Atamurotov
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Deformation Parameter ◽  
Space Time ◽  
Black Hole Spin ◽  
Spin Parameter ◽  
Kerr Space ◽  
The One

AbstractThe shadow of a Kerr-like black hole has been considered and it was shown that in addition to the specific angular momentum a, deformation parameter of Kerr-like space-time essentially deforms the shape of the black hole shadow. For a given value of the black hole spin parameter a, the presence of a deformation parameter ε reduces the shadow and enlarges its deformation with respect to the one in the Kerr space-time.

The gravitational perturbations of the Kerr black hole IV. The completion of the solutiont

1980 ◽  
Vol 372 (1751) ◽  
pp. 475-484 ◽  
Keyword(s):  
Black Hole ◽  
Kerr Black Hole ◽  
Space Time ◽  
Gravitational Perturbations ◽  
Kerr Space ◽  
The One

This paper eliminates the last remaining lacuna in the information that was needed to make the solution for the perturbations in the metric coefficients of the Kerr space-time fully explicit. The requisite information is obtained from a pair of equations which is complementary to the one considered in paper III; and the solution of the Newman-Penrose equations governing the perturbations is, thus, completed.

Bound orbits around modified Hayward black holes

2021 ◽  
Author(s):  
Bo Gao ◽  
Xue-Mei Deng
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Gravitational Field ◽  
Periodic Orbits ◽  
Kerr Black Hole ◽  
Periodic Oscillations ◽  
Test Particles ◽  
Spin Parameter ◽  
Bound Orbits

The neutral time-like particle’s bound orbits around modified Hayward black holes have been investigated. We find that both in the marginally bound orbits (MBO) and the innermost stable circular orbits (ISCO), the test particle’s radius and its angular momentum are all more sensitive to one of the parameters [Formula: see text]. Especially, modified Hayward black holes with [Formula: see text] could mimic the same ISCO radius around the Kerr black hole with the spin parameter up to [Formula: see text]. Small [Formula: see text] could mimic the ISCO of small-spinning test particles around Schwarzschild black holes. Meanwhile, rational (periodic) orbits around modified Hayward black holes have also been studied. The epicyclic frequencies of the quasi-circular motion around modified Hayward black holes are calculated and discussed with respect to the observed Quasi-periodic oscillations (QPOs) frequencies. Our results show that rational orbits around modified Hayward black holes have different values of the energy from the ones of Schwarzschild black holes. The epicyclic frequencies in modified Hayward black holes have different frequencies from Schwarzschild and Kerr ones. These might provide hints for distinguishing modified Hayward black holes from Schwarzschild and Kerr ones by using the dynamics of time-like particles around the strong gravitational field.

scholarly journals Hawking Non-thermal and Purely Thermal Radiations of Rotating Black Hole in Anti-de Sitter Space Time by Hamilton-Jacobi Method

2018 ◽  
Vol 37 ◽  
pp. 99-109
Author(s):  
M Ilias Hossain
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Emission Spectrum ◽  
Hawking Radiation ◽  
De Sitter Space ◽  
Space Time ◽  
Jacobi Method ◽  
De Sitter ◽  
Tunneling Method ◽  
Thermal Radiations

We have explored Hawking non-thermal and purely thermal radiations of Kerr-anti-de Sitter (KAdS) black hole using massive particles tunneling method by taking into account the space time background as dynamical, energy and angular momentum as conserved incorporating the selfgravitation effect of the emitted particles. The results we have obtained for KAdS black hole have shown that the tunneling rates are related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum and also the obtaining results for KAdS black hole are accordant with Parikh and Wilczek’s opinion and gives a correction to the Hawking radiation of KAdS black hole.GANIT J. Bangladesh Math. Soc.Vol. 37 (2017) 99-109

Shadow of a disformal Kerr black hole in quadratic degenerate higher-order scalar–tensor theories

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Fen Long ◽  
Songbai Chen ◽  
Mingzhi Wang ◽  
Jiliang Jing
Keyword(s):  
Black Hole ◽  
Deformation Parameter ◽  
Kerr Black Hole ◽  
Arbitrary Spin ◽  
Higher Order ◽  
Fractal Structures ◽  
Extreme Black Hole ◽  
Spin Parameter ◽  
Result Show ◽  
Self Similar

AbstractWe have studied the shadow of a disformal Kerr black hole with an extra deformation parameter, which belongs to non-stealth rotating solutions in quadratic degenerate higher-order scalar–tensor (DHOST) theory. Our result show that the size of the shadow increases with the deformation parameter for the black hole with arbitrary spin parameter. However, the effect of the deformation parameter on the shadow shape depends heavily on the spin parameter of black hole and the sign of the deformation parameter. The change of the shadow shape becomes more distinct for the black hole with the more quickly rotation and the more negative deformation parameter. Especially, for the near-extreme black hole with negative deformation parameter, there exist a “pedicel”-like structure appeared in the shadow, which increases with the absolute value of deformation parameter. The eyebrow-like shadow and the self-similar fractal structures also appear in the shadow for the disformal Kerr black hole in DHOST theory. These features in the black hole shadow originating from the scalar field could help us to understand the non-stealth disformal Kerr black hole and quadratic DHOST theory.

scholarly journals On the Difference Between Radio Quiet and Radio Loud AGN

1997 ◽  
Vol 163 ◽  
pp. 761-762 ◽  
Author(s):  
P. Marziani ◽  
M. Calvani ◽  
J. W. Sulentic
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Systematic Difference ◽  
Central Black Hole ◽  
Black Hole Spin ◽  
The Difference

AbstractA systematic difference in alignment between the central black hole spin and the angular momentum of the accreting gas may help to explain several differences found in the optical and UV HST spectra of radio loud and radio quiet AGN.

scholarly journals Possible imprints of cosmic strings in the shadows of galactic black holes

2014 ◽  
Vol 23 (07) ◽  
pp. 1450060 ◽  
Author(s):  
Vassil K. Tinchev ◽  
Stoytcho S. Yazadjiev
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmic String ◽  
Cosmic Strings ◽  
Kerr Black Hole ◽  
Black Hole Spin ◽  
Deficit Angle ◽  
Spin Parameter ◽  
Shadow Cast

We examine the shadow cast by a Kerr black hole pierced by a cosmic string. The observable images depend not only on the black hole spin parameter and the angle of inclination, but also on the deficit angle yielded by the cosmic string. The dependence of the observable characteristics of the shadow on the deficit angle is explored. The imprints in the black hole shadow left by the presence of a cosmic string can serve in principle as a method for observational detection of such strings.

Observing the contour profile of a Kerr–Sen black hole

2018 ◽  
Vol 33 (17) ◽  
pp. 1850099 ◽  
Author(s):  
X. G. Lan ◽  
J. Pu
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Naked Singularity ◽  
Extremal Case ◽  
Distortion Parameter ◽  
Rotating Black Hole ◽  
Dark Zone ◽  
Spin Parameter ◽  
The Mean ◽  
In The Beginning

In this paper, the shadow and the corresponding naked singularity cast by a Kerr–Sen black hole are studied. It is found that the shadow of a rotating black hole would be a dark zone surrounded by a deformed circle, and the shadow is distorted more away from a circle when the black hole approaches the extremal case. Besides, it is shown that the mean radius of the shadow decreases and distortion parameter increases with the increasing of charge, respectively. However, the mean radius and the distortion parameter vary complicatedly with the change of spin parameter. In the beginning, both observables decrease rapidly with the increasing of specific angular momentum, nevertheless, they increase slightly in the latter part. These results show that there would be a significant effect of the spin on the shadows, which would be of great importance for probing the nature of the black hole.

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