scholarly journals Black hole spin axis in numerical relativity

2019 ◽  
Vol 99 (8) ◽  
Author(s):  
Robert Owen ◽  
Alex S. Fox ◽  
John A. Freiberg ◽  
Terrence Pierre Jacques
Keyword(s):  
Black Hole ◽  
Numerical Relativity ◽  
Spin Axis ◽  
Black Hole Spin

scholarly journals B0707−359: a case study of change in AGN–black hole spin axis

2013 ◽  
Vol 436 (1) ◽  
pp. 690-696 ◽  
Author(s):  
L. Saripalli ◽  
J. M. Malarecki ◽  
R. Subrahmanyan ◽  
D. H. Jones ◽  
L. Staveley-Smith
Keyword(s):  
Black Hole ◽  
Spin Axis ◽  
Black Hole Spin

scholarly journals Influence of the geometric configuration of accretion flow on the black hole spin dependence of relativistic acoustic geometry

2018 ◽  
Vol 27 (03) ◽  
pp. 1850023 ◽  
Author(s):  
Pratik Tarafdar ◽  
Tapas K. Das
Keyword(s):  
Black Hole ◽  
Kerr Black Hole ◽  
Geometric Configuration ◽  
Surface Gravity ◽  
Linear Perturbation ◽  
Flow Profile ◽  
White Hole ◽  
Accretion Flow ◽  
Black Hole Spin ◽  
General Relativistic

Linear perturbation of general relativistic accretion of low angular momentum hydrodynamic fluid onto a Kerr black hole leads to the formation of curved acoustic geometry embedded within the background flow. Characteristic features of such sonic geometry depend on the black hole spin. Such dependence can be probed by studying the correlation of the acoustic surface gravity [Formula: see text] with the Kerr parameter [Formula: see text]. The [Formula: see text]–[Formula: see text] relationship further gets influenced by the geometric configuration of the accretion flow structure. In this work, such influence has been studied for multitransonic shocked accretion where linear perturbation of general relativistic flow profile leads to the formation of two analogue black hole-type horizons formed at the sonic points and one analogue white hole-type horizon which is formed at the shock location producing divergent acoustic surface gravity. Dependence of the [Formula: see text]–[Formula: see text] relationship on the geometric configuration has also been studied for monotransonic accretion, over the entire span of the Kerr parameter including retrograde flow. For accreting astrophysical black holes, the present work thus investigates how the salient features of the embedded relativistic sonic geometry may be determined not only by the background spacetime, but also by the flow configuration of the embedding matter.

scholarly journals Spectral and polarization properties of black hole accretion disc emission: including absorption effects

2020 ◽  
Author(s):  
R Taverna ◽  
L Marra ◽  
S Bianchi ◽  
M Dovčiak ◽  
R Goosmann ◽  
...  
Keyword(s):  
Black Hole ◽  
Polarization State ◽  
General Rule ◽  
Accretion Disc ◽  
Accretion Discs ◽  
Polarization Degree ◽  
Monte Carlo Code ◽  
Black Hole Spin ◽  
Black Hole Accretion ◽  
Hole Accretion

Abstract The study of radiation emitted from black hole accretion discs represents a crucial way to understand the main physical properties of these sources, and in particular the black hole spin. Beside spectral analysis, polarimetry is becoming more and more important, motivated by the development of new techniques which will soon allow to perform measurements also in the X- and γ-rays. Photons emitted from black hole accretion discs in the soft state are indeed expected to be polarized, with an energy dependence which can provide an estimate of the black hole spin. Calculations performed so far, however, considered scattering as the only process to determine the polarization state of the emitted radiation, implicitly assuming that the temperatures involved are such that material in the disc is entirely ionized. In this work we generalize the problem by calculating the ionization structure of a surface layer of the disc with the public code cloudy, and then by determining the polarization properties of the emerging radiation using the Monte Carlo code stokes. This allows us to account for absorption effects alongside scattering ones. We show that including absorption can deeply modify the polarization properties of the emerging radiation with respect to what is obtained in the pure-scattering limit. As a general rule, we find that the polarization degree is larger when absorption is more important, which occurs e.g. for low accretion rates and/or spins when the ionization of the matter in the innermost accretion disc regions is far from complete.

scholarly journals NuSTAR OBSERVATIONS OF THE BLACK HOLE GS 1354–645: EVIDENCE OF RAPID BLACK HOLE SPIN

2016 ◽  
Vol 826 (1) ◽  
pp. L12 ◽  
Author(s):  
A. M. El-Batal ◽  
J. M. Miller ◽  
M. T. Reynolds ◽  
S. E. Boggs ◽  
F. E. Chistensen ◽  
...  
Keyword(s):  
Black Hole ◽  
Black Hole Spin

scholarly journals Deciphering Black Hole Spin, Inclination angle & Charge From Kerr Shadow

2021 ◽  
Author(s):  
Deep Bhattacharjee
Keyword(s):  
Black Hole ◽  
Inclination Angle ◽  
Kerr Black Hole ◽  
Full Description ◽  
Underlying Theory ◽  
Black Hole Spin

The apparent shape of the black hole shadow provides a full description of the spin, the inclination angle and the charge of a Kerr black hole, without any astrophysical process or underlying theory in the astrophysical process.

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