scholarly journals General relativistic numerical simulation of sub-Keplerian transonic accretion flows on to rotating black holes: Kerr space–time

2018 ◽  
Vol 482 (3) ◽  
pp. 3636-3645 ◽  
Author(s):  
Jinho Kim ◽  
Sudip K Garain ◽  
Sandip K Chakrabarti ◽  
Dinshaw S Balsara
Keyword(s):  
Numerical Simulation ◽  
Black Holes ◽  
Space Time ◽  
Accretion Flows ◽  
Rotating Black Holes ◽  
Kerr Space ◽  
General Relativistic

scholarly journals General relativistic numerical simulation of sub-Keplerian transonic accretion flows on to black holes: Schwarzschild space–time

2017 ◽  
Vol 472 (1) ◽  
pp. 542-549 ◽  
Author(s):  
Jinho Kim ◽  
Sudip K. Garain ◽  
Dinshaw S. Balsara ◽  
Sandip K. Chakrabarti
Keyword(s):  
Numerical Simulation ◽  
Black Holes ◽  
Space Time ◽  
Accretion Flows ◽  
General Relativistic

scholarly journals Plasmoid formation in global GRMHD simulations and AGN flares

2020 ◽  
Vol 495 (2) ◽  
pp. 1549-1565 ◽  
Author(s):  
Antonios Nathanail ◽  
Christian M Fromm ◽  
Oliver Porth ◽  
Hector Olivares ◽  
Ziri Younsi ◽  
...  
Keyword(s):  
Black Holes ◽  
Dipolar Field ◽  
Relativistic Jets ◽  
Poloidal Magnetic Field ◽  
Accretion Flows ◽  
Rotating Black Holes ◽  
General Relativistic ◽  
Formation And Evolution ◽  
Magnetohydrodynamic Simulations ◽  
Dissipation Processes

ABSTRACT One of the main dissipation processes acting on all scales in relativistic jets is thought to be governed by magnetic reconnection. Such dissipation processes have been studied in idealized environments, such as reconnection layers, which evolve in merging islands and lead to the production of ‘plasmoids’, ultimately resulting in efficient particle acceleration. In accretion flows on to black holes, reconnection layers can be developed and destroyed rapidly during the turbulent evolution of the flow. We present a series of two-dimensional general-relativistic magnetohydrodynamic simulations of tori accreting on to rotating black holes focusing our attention on the formation and evolution of current sheets. Initially, the tori are endowed with a poloidal magnetic field having a multiloop structure along the radial direction and with an alternating polarity. During reconnection processes, plasmoids and plasmoid chains are developed leading to a flaring activity and hence to a variable electromagnetic luminosity. We describe the methods developed to track automatically the plasmoids that are generated and ejected during the simulation, contrasting the behaviour of multiloop initial data with that encountered in typical simulations of accreting black holes having initial dipolar field composed of one loop only. Finally, we discuss the implications that our results have on the variability to be expected in accreting supermassive black holes.

scholarly journals Two temperature viscous accretion flows around rotating black holes: Description of under-fed systems to ultra-luminous X-ray sources

New Astronomy ◽  
2010 ◽  
Vol 15 (3) ◽  
pp. 283-291 ◽  
Author(s):  
S.R. Rajesh ◽  
Banibrata Mukhopadhyay
Keyword(s):  
Black Holes ◽  
X Ray ◽  
Accretion Flows ◽  
Rotating Black Holes ◽  
Two Temperature

A “Horizon-adapted” Approach to the Study of Relativistic Accretion Flows onto Rotating Black Holes

1998 ◽  
Vol 507 (1) ◽  
pp. L67-70 ◽  
Author(s):  
José A. Font ◽  
José Ma. Ibáñez ◽  
Philippos Papadopoulos
Keyword(s):  
Black Holes ◽  
Accretion Flows ◽  
Rotating Black Holes

scholarly journals Transonic accretion and winds around Pseudo-Kerr black holes andcomparison with general relativistic solutions

2022 ◽  
Author(s):  
Abhrajit Bhattacharjee ◽  
Sandip Kumar Chakrabarti ◽  
Dipak Debnath
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Time Scale ◽  
Momentum Equation ◽  
Accretion Flows ◽  
Timing Properties ◽  
Surrounding Space ◽  
General Relativistic ◽  
Corotating Frame

Abstract Spectral and timing properties of accretion flows on a black hole depend on their density and temperature distributions, which, in turn come from the underlying dynamics. Thus, an accurate description of the flow which includes hydrodynamics and radiative transfer is a must to interpret the observational results. In the case of non-rotating black holes, Pseudo- Newtonian description of surrounding space-time enables one to make a significant progress in predicting spectral and timing properties. This formalism is lacking for the spinning black holes. In this paper, we show that there exists an exact form of ‘natural’ potential derivable from the general relativistic (GR) radial momentum equation written in the local corotating frame. Use of this potential in an otherwise Newtonian set of equations, allows us to describe transonic flows very accurately as is evidenced by comparing with solutions obtained from the full GR framework. We study the properties of the sonic points and the centrifugal pressure supported shocks in the parameter space spanned by the specific energy and the angular momentum, and compare with the results of GR hydrodynamics. We show that this potential can safely be used for the entire range of Kerr parameter −1 < a < 1 for modeling of observational results around spinning black holes. We assume the flow to be inviscid. Thus, it is non-dissipative with constant energy and angular momentum. These assumptions are valid very close to the black hole horizon as the infall time scale is much shorter as compared to the viscous time scale.

scholarly journals SUPERMASSIVE BLACK HOLES OR BOSON STARS? HAIR COUNTING WITH GRAVITATIONAL WAVE DETECTORS

2006 ◽  
Vol 15 (12) ◽  
pp. 2209-2216 ◽  
Author(s):  
EMANUELE BERTI ◽  
VITOR CARDOSO
Keyword(s):  
Black Holes ◽  
Laser Interferometer ◽  
Kerr Black Hole ◽  
Space Time ◽  
Multipole Moments ◽  
Boson Stars ◽  
Laser Interferometer Space Antenna ◽  
Kerr Space ◽  
Oscillation Frequencies ◽  
Rule Out

The evidence for supermassive Kerr black holes in galactic centers is strong and growing, but only the detection of gravitational waves will convincingly rule out other possibilities to explain the observations. The Kerr space–time is completely specified by the first two multipole moments: mass and angular momentum. This is usually referred to as the "no-hair theorem," but it is really a "two-hair" theorem. If general relativity is the correct theory of gravity, the most plausible alternative to a supermassive Kerr black hole is a rotating boson star. Numerical calculations indicate that the space–time of rotating boson stars is determined by the first three multipole moments ("three-hair theorem"). The Laser Interferometer Space Antenna (LISA) could accurately measure the oscillation frequencies of these supermassive objects. We propose to use these measurements to "count their hair," unambiguously determining their nature and properties.

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