Shock Formation in Adiabatic Accretion Flows around a Kerr Black Hole

1999 ◽  
pp. 61-72
Author(s):  
Ju-Fu Lu
Keyword(s):  
Black Hole ◽  
Kerr Black Hole ◽  
Shock Formation ◽  
Accretion Flows

Effects of magnetohydrodynamic accretion flows on global structure of a Kerr black-hole magnetosphere

1991 ◽  
Vol 44 (8) ◽  
pp. 2295-2305 ◽  
Author(s):  
Shin-ya Nitta ◽  
Masaaki Takahashi ◽  
Akira Tomimatsu
Keyword(s):  
Black Hole ◽  
Kerr Black Hole ◽  
Global Structure ◽  
Accretion Flows

scholarly journals Status of GRMHD simulations and radiative models of Sgr A*

2016 ◽  
Vol 11 (S322) ◽  
pp. 43-49
Author(s):  
Monika Mościbrodzka
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Kerr Black Hole ◽  
Theoretical Models ◽  
Radiative Properties ◽  
X Ray ◽  
Accretion Flows ◽  
General Relativistic ◽  
Sgr A ◽  
Magnetohydrodynamic Simulations

AbstractThe Galactic center is a perfect laboratory for testing various theoretical models of accretion flows onto a supermassive black hole. Here, I review general relativistic magnetohydrodynamic simulations that were used to model emission from the central object - Sgr A*. These models predict dynamical and radiative properties of hot, magnetized, thick accretion disks with jets around a Kerr black hole. Models are compared to radio-VLBI, mm-VLBI, NIR, and X-ray observations of Sgr A*. I present the recent constrains on the free parameters of the model such as accretion rate onto the black hole, the black hole angular momentum, and orientation of the system with respect to our line of sight.

scholarly journals Choked accretion onto a Kerr black hole

2021 ◽  
Vol 103 (2) ◽  
Author(s):  
Alejandro Aguayo-Ortiz ◽  
Olivier Sarbach ◽  
Emilio Tejeda
Keyword(s):  
Black Hole ◽  
Kerr Black Hole

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.

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.

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