scholarly journals Scale-invariance of black hole accretion: modelling emission from a black hole X-ray binary with relativistic accretion flow simulations

2019 ◽  
Vol 490 (4) ◽  
pp. 5353-5358
Author(s):  
M Mościbrodzka
Keyword(s):  
Black Hole ◽  
Near Infrared ◽  
Thermal Emission ◽  
Broad Band ◽  
Scale Invariant ◽  
X Ray ◽  
Accretion Flow ◽  
Black Hole Accretion ◽  
Sgr A ◽  
Hole Accretion

ABSTRACT We model the non-thermal emission spectrum of the extremely sub-Eddington X-ray binary system A0620-00. It is believed that this non-thermal emission is produced by radiatively inefficient ‘quiescent’ accretion on to a stellar-mass black hole present in the system. We post-process general relativistic magnetohydrodynamics (GRMHD) simulations with multiwavelength, fully polarized, relativistic radiative transfer calculations to predict broad-band spectra and emission polarization levels for a range of electron models and accretion rates. We find that a model with strong coupling of electrons and ions in the accretion disc and accretion rate of only $\dot{M}=3\times 10^{-13} \, \rm [M_\odot \, yr^{-1}]$ is able to recover the observed X-ray spectral slope, as well as the excess of linear polarization detected in the source in the near-infrared (NIR)/optical bands. Our models constrain the spectral properties of a putative relativistic jet produced in this system. In addition, we show that the magnetized winds from our hot accretion flow carry away a small fraction of the orbital angular momentum of the binary, which is unable to explain the observed rapid orbital decay of the system. GRMHD simulations similar to the present ones are often used to explain emission from sub-Eddington supermassive black holes in Sgr A* or M87; the present simulations allow us to test whether some aspects of quiescent black hole accretion are scale-invariant.

scholarly journals The 3 Ms Chandra campaign on Sgr A*: a census of X-ray flaring activity from the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 374-378
Author(s):  
J. Neilsen ◽  
M. A. Nowak ◽  
C. Gammie ◽  
J. Dexter ◽  
S. Markoff ◽  
...  
Keyword(s):  
Black Hole ◽  
Spectral Resolution ◽  
Galactic Center ◽  
Progress Report ◽  
Deep Sleep ◽  
X Ray ◽  
Supermassive Black Hole ◽  
Black Hole Accretion ◽  
Sgr A ◽  
Hole Accretion

AbstractOver the last decade, X-ray observations of Sgr A* have revealed a black hole in a deep sleep, punctuated roughly once per day by brief flares. The extreme X-ray faintness of this supermassive black hole has been a long-standing puzzle in black hole accretion. To study the accretion processes in the Galactic center, Chandra (in concert with numerous ground- and space-based observatories) undertook a 3 Ms campaign on Sgr A* in 2012. With its excellent observing cadence, sensitivity, and spectral resolution, this Chandra X-ray Visionary Project (XVP) provides an unprecedented opportunity to study the behavior of the closest supermassive black hole. We present a progress report from our ongoing study of X-ray flares, including the brightest flare ever seen from Sgr A*. Focusing on the statistics of the flares and the quiescent emission, we discuss the physical implications of X-ray variability in the Galactic center.

scholarly journals Probing black hole accretion tracks, scaling relations, and radiative efficiencies from stacked X-ray active galactic nuclei

2019 ◽  
Vol 493 (1) ◽  
pp. 1500-1511 ◽  
Author(s):  
Francesco Shankar ◽  
David H Weinberg ◽  
Christopher Marsden ◽  
Philip J Grylls ◽  
Mariangela Bernardi ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Selection Bias ◽  
Stellar Mass ◽  
Supermassive Black Holes ◽  
Independent Evidence ◽  
X Ray ◽  
Black Hole Accretion ◽  
Black Hole Masses ◽  
Hole Accretion

ABSTRACT The masses of supermassive black holes at the centres of local galaxies appear to be tightly correlated with the mass and velocity dispersions of their galactic hosts. However, the local Mbh–Mstar relation inferred from dynamically measured inactive black holes is up to an order-of-magnitude higher than some estimates from active black holes, and recent work suggests that this discrepancy arises from selection bias on the sample of dynamical black hole mass measurements. In this work, we combine X-ray measurements of the mean black hole accretion luminosity as a function of stellar mass and redshift with empirical models of galaxy stellar mass growth, integrating over time to predict the evolving Mbh–Mstar relation. The implied relation is nearly independent of redshift, indicating that stellar and black hole masses grow, on average, at similar rates. Matching the de-biased local Mbh–Mstar relation requires a mean radiative efficiency ε ≳ 0.15, in line with theoretical expectations for accretion on to spinning black holes. However, matching the ‘raw’ observed relation for inactive black holes requires ε ∼ 0.02, far below theoretical expectations. This result provides independent evidence for selection bias in dynamically estimated black hole masses, a conclusion that is robust to uncertainties in bolometric corrections, obscured active black hole fractions, and kinetic accretion efficiency. For our fiducial assumptions, they favour moderate-to-rapid spins of typical supermassive black holes, to achieve ε ∼ 0.12–0.20. Our approach has similarities to the classic Soltan analysis, but by using galaxy-based data instead of integrated quantities we are able to focus on regimes where observational uncertainties are minimized.

Supermassive Black Hole Accretion History Inferred from a Large Sample of [ITAL]CHANDRA[/ITAL][ITAL]Chandra[/ITAL] Hard X-Ray Sources

2001 ◽  
Vol 122 (5) ◽  
pp. 2177-2189 ◽  
Author(s):  
A. J. Barger ◽  
L. L. Cowie ◽  
M. W. Bautz ◽  
W. N. Brandt ◽  
G. P. Garmire ◽  
...  
Keyword(s):  
Black Hole ◽  
Large Sample ◽  
X Ray ◽  
Supermassive Black Hole ◽  
Black Hole Accretion ◽  
Hole Accretion

ACCRETION PROBLEM IN A KERR BLACK HOLE GEOMETRY VIEWED AS FLOWS IN CONVERGING–DIVERGING DUCTS

2010 ◽  
Vol 19 (13) ◽  
pp. 2059-2069
Author(s):  
K. CHAKRABARTI ◽  
M. M. MAJUMDAR ◽  
SANDIP K. CHAKRABARTI
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Mach Number ◽  
Cross Sections ◽  
Kerr Black Hole ◽  
Flat Space ◽  
Accretion Flow ◽  
Black Hole Accretion ◽  
Hole Geometry ◽  
Hole Accretion

Accretion flow on a horizon is supersonic, no matter what the flow angular momentum or the spin of the black hole is. This means that a black hole accretion can always be viewed as a flow in a flat space–time through one or more convergent–divergent ducts. In this paper, we study how the area of cross-sections must vary in order that the flow has the same properties in both systems. We show that the accretion flow experiencing a shock is equivalent to having two ducts connected back-to-back, both with a neck where the flow becomes supersonic. We study the pressure and Mach number variations for corotating, contrarotating flows and flows around a black hole with evolving spin.

scholarly journals High-Frequency QPOs and Overstable Oscillations of Black-Hole Accretion Disks

2012 ◽  
Vol 8 (S290) ◽  
pp. 57-61 ◽  
Author(s):  
Dong Lai ◽  
Wen Fu ◽  
David Tsang ◽  
Jiri Horak ◽  
Cong Yu
Keyword(s):  
Black Hole ◽  
Accretion Disks ◽  
High Frequency ◽  
Oscillation Mode ◽  
Relativistic Effects ◽  
X Ray ◽  
Black Hole Accretion ◽  
General Relativistic ◽  
X Ray Binaries ◽  
Hole Accretion

AbstractThe physical origin of high-frequency QPOs (HFQPOs) in black-hole X-ray binaries remains an enigma despite many years of detailed observational studies. Although there exists a number of models for HFQPOs, many of these are simply “notions” or “concepts” without actual calculation derived from fluid or disk physics. Future progress requires a combination of numerical simulations and semi-analytic studies to extract physical insights. We review recent works on global oscillation modes in black-hole accretion disks, and explain how, with the help of general relativistic effects, the energy stored in the disk differential rotation can be pumped into global spiral density modes in the disk, making these modes grow to large amplitudes under certain conditions (“corotational instability”). These modes are robust in the presence of disk magnetic fields and turbulence. The computed oscillation mode frequencies are largely consistent with the observed values for HFQPOs in BH X-ray binaries. The approximate 2:3 frequency ratio is also expected from this model. The connection of HFQPOs with other disk properties (such as production of episodic jets) is also discussed.

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