Testing propagating mass accretion rate fluctuations model PROPFLUC on black hole X-ray binaries

2016 ◽  
Vol 337 (4-5) ◽  
pp. 524-528
Author(s):  
S. Rapisarda ◽  
A. Ingram ◽  
M. van der Klis
Keyword(s):  
Black Hole ◽  
Accretion Rate ◽  
X Ray ◽  
Mass Accretion Rate ◽  
X Ray Binaries

scholarly journals Radiative efficiency of hot accretion flow and the radio/X-ray correlation in X-ray binaries

2014 ◽  
Vol 10 (S312) ◽  
pp. 139-140
Author(s):  
Fu-Guo Xie
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Rate ◽  
Galactic Nuclei ◽  
X Ray ◽  
Radiative Efficiency ◽  
Accretion Flow ◽  
Accretion Rates ◽  
Distinctive Property ◽  
X Ray Binaries

AbstractSignificant progresses have been made since the discovery of hot accretion flow, a theory successfully applied to the low-luminosity active galactic nuclei (LLAGNs) and black hole (BH) X-ray binaries (BHBs) in their hard states. Motivated by these updates, we re-investigate the radiative efficiency of hot accretion flow. We find that, the brightest regime of hot accretion flow shows a distinctive property, i.e. it has a constant efficiency independent of accretion rates, similar to the standard thin disk. For less bright regime, the efficiency has a steep positive correlation with the accretion rate, while for faint regime typical of advection-dominated accretion flow, the correlation is shadower. This result can naturally explain the observed two distinctive correlations between radio and X-ray luminosities in black hole X-ray binaries. The key difference in systems with distinctive correlations could be the viscous parameter, which determines the critical luminosity of different accretion modes.

scholarly journals Propagating mass accretion rate fluctuations in X-ray binaries under the influence of viscous diffusion

2017 ◽  
Vol 474 (2) ◽  
pp. 2259-2276 ◽  
Author(s):  
Alexander A Mushtukov ◽  
Adam Ingram ◽  
Michiel van der Klis
Keyword(s):  
Accretion Rate ◽  
X Ray ◽  
Mass Accretion Rate ◽  
X Ray Binaries

Clumpy wind accretion in Supergiant X-ray Binaries

2018 ◽  
Vol 14 (S346) ◽  
pp. 34-39
Author(s):  
Ileyk El Mellah ◽  
Andreas A. C. Sander ◽  
Jon O. Sundqvist ◽  
Rony Keppens
Keyword(s):  
Neutron Star ◽  
Accretion Rate ◽  
Recent Analysis ◽  
Line Of Sight ◽  
Time Variability ◽  
X Ray ◽  
Mass Accretion Rate ◽  
Accretion Process ◽  
The Impact ◽  
X Ray Binaries

AbstractSupergiant X-ray Binaries host a compact object, generally a neutron star, orbiting an evolved O/B star. Mass transfer proceeds through the intense radiatively-driven wind of the stellar donor, a fraction of which is captured by the gravitational field of the neutron star. The subsequent accretion process onto the neutron star is responsible for the abundant X-ray emission from those systems. They also display variations in time of the X-ray flux by a factor of a few 10, along with changes in the hardness ratios believed to be due to varying absorption along the line-of-sight. We used the most recent results on the inhomogeneities (aka clumps) in the non-stationary wind of massive hot stars to evaluate their impact on the time-variable accretion process. We ran three-dimensional simulations of the wind in the vicinity of the accretor to witness the formation of the bow shock and follow the inhomogeneous flow over several spatial orders of magnitude, down to the neutron star magnetosphere. In particular, we show that the impact of the clumps on the time-variability of the intrinsic mass accretion rate is severely damped by the crossing of the shock, compared to the purely ballistic Bondi-Hoyle-Lyttleton estimation. We also account for the variable absorption due to clumps passing by the line-of-sight and estimate the final effective variability of the mass accretion rate for different orbital separations. These results are confronted to recent analysis of Vela X-1 observations with Chandra by Grinberg et al. (2017). It shows that clumps account well for time-variability at low luminosity but can not generate, per se, the high luminosity activity observed.

scholarly journals MHD Accretion Disk Winds: The Key to AGN Phenomenology?

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 13 ◽  
Author(s):  
Demosthenes Kazanas
Keyword(s):  
Black Hole ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Mass Flux ◽  
Accretion Rate ◽  
Compact Object ◽  
Mass Scale ◽  
Observational Constraints ◽  
X Ray ◽  
Mass Accretion Rate

Accretion disks are the structures which mediate the conversion of the kinetic energy of plasma accreting onto a compact object (assumed here to be a black hole) into the observed radiation, in the process of removing the plasma’s angular momentum so that it can accrete onto the black hole. There has been mounting evidence that these structures are accompanied by winds whose extent spans a large number of decades in radius. Most importantly, it was found that in order to satisfy the winds’ observational constraints, their mass flux must increase with the distance from the accreting object; therefore, the mass accretion rate on the disk must decrease with the distance from the gravitating object, with most mass available for accretion expelled before reaching the gravitating object’s vicinity. This reduction in mass flux with radius leads to accretion disk properties that can account naturally for the AGN relative luminosities of their Optical-UV and X-ray components in terms of a single parameter, the dimensionless mass accretion rate. Because this critical parameter is the dimensionless mass accretion rate, it is argued that these models are applicable to accreting black holes across the mass scale, from galactic to extragalactic.

scholarly journals The impact of thermal winds on the outburst lightcurves of black hole X-ray binaries

2019 ◽  
Vol 632 ◽  
pp. A40 ◽  
Author(s):  
Guillaume Dubus ◽  
Chris Done ◽  
Bailey E. Tetarenko ◽  
Jean-Marie Hameury
Keyword(s):  
Black Hole ◽  
Mass Loss ◽  
Accretion Rate ◽  
Strong Wind ◽  
X Rays ◽  
X Ray ◽  
Thermal Wind ◽  
Viscous Instability ◽  
The Impact ◽  
X Ray Binaries

Context. The observed signatures of winds from X-ray binaries are broadly consistent with thermal winds, which are driven by X-ray irradiation of the outer accretion disc. Thermal winds produce mass outflow rates that can exceed the accretion rate in the disc. Aims. We aim to study the impact of thermal wind mass loss on the stability and lightcurves of black hole X-ray binaries subject to the thermal-viscous instability driving their outbursts. Strong mass loss could stop outbursts early, as proposed for the 2015 outburst of V404 Cyg. Methods. We used an analytical model for thermal (Compton) wind mass loss as a function of radius, X-ray spectrum, and luminosity that was calibrated against numerical simulations. We also estimated the fraction of the X-rays, emitted close to the compact object, that are scattered back to the outer disc in the wind. Scattering in the thermal wind couples irradiation to the disc size and inner mass accretion rate. The disc evolution equations were modified to include this wind mass loss and the varying irradiation fraction. Results. Scattering in the strong wind expected of long Porb systems enhances the irradiation heating of the outer disc, keeping it stable against the thermal-viscous instability. This accounts very well for the existence of persistently bright systems with large discs, such as Cyg X-2, 1E 1740.7−2942, or GRS 1758−258. Mass loss from the thermal wind shortens the outburst, as expected, but it is insufficient in explaining the rapid decay timescale of black-hole X-ray binary outbursts. However, including the wind-related varying irradiation fraction produces lightcurves with plateaus in long Porb systems like GRO J1655−40. Plateau lightcurves may be a dynamical signature of enhanced irradiation due to scattering in thermal winds. Conclusions. Mass loss due to thermal winds is not a major driver for the outburst dynamics up to luminosities of 0.1 − 0.2 LEdd. Higher luminosities may produce stronger mass loss but studying them is complicated since the wind becomes opaque. Magnetic winds, which extract angular momentum with little mass loss, seem more promising to explain the fast decay timescales generically seen in black-hole X-ray binaries. Thermal winds can play an important role in the outburst dynamics through the varying irradiation heating. This may be evidenced by relating changes in wind properties, X-ray spectra, or luminosity with changes in the optical emission that traces the outer disc. Simulations should enable more accurate estimates of the dependence of the irradiation onto the disc as a function of irradiation spectrum, radius, and disc wind properties.

scholarly journals Black Hole Binaries in Quiescence

2016 ◽  
Vol 12 (S324) ◽  
pp. 35-38
Author(s):  
Charles D. Bailyn
Keyword(s):  
Black Hole ◽  
Binary Systems ◽  
Accretion Rate ◽  
Quiescent State ◽  
X Ray ◽  
Black Hole Binaries ◽  
Key Factor ◽  
Black Hole Binary ◽  
Limiting Case ◽  
X Ray Binaries

AbstractI discuss some of what is known and unknown about the behavior of black hole binary systems in the quiescent accretion state. Quiescence is important for several reasons: 1) the dominance of the companion star in optical and IR wavelengths allows the binary parameters to be robustly determined — as an example, we argue that the longer proposed distance to the X-ray source GRO J1655-40 is correct; 2) quiescence represents the limiting case of an extremely low accretion rate, in which both accretion and jets can be observed; 3) understanding the evolution and duration of the quiescent state is a key factor in determining the overall demographics of X-ray binaries, which has taken on a new importance in the era of gravitational wave astronomy.

scholarly journals Big Game Hunting in the Andromeda Galaxy: Identifying and Weighing Black Holes in Low Mass X-Ray Binaries

2004 ◽  
Vol 194 ◽  
pp. 71-72
Author(s):  
R. Barnard
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Star ◽  
Power Density ◽  
Accretion Rate ◽  
Power Density Spectrum ◽  
Density Spectrum ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractWe have devised a new technique for identifying stellar mass black holes in low mass X-ray binaries, and have applied it to XMM-Newton observations of two X-ray sources in M31. In particular we search for low accretion rate power density spectra; these are very similar for all LMXB, whether the primary is a black hole or a neutron star. Galactic neutron star LMXB exhibit these distinctive PDS at very low luminosities (~ 1036 erg s–1) while black hole LMXB can exhibit them at luminosities > 1038 erg s–1! Following the work of van der Klis (1994), we assume a maximum accretion rate (as a fraction of the Eddington limit) for low accretion rate PDS that is constant for all LMXB, and obtain an empirical value of ~10% Eddington. We have so far discovered two candidate black hole binaries in M31, exhibiting low accretion rate PDS at up to 3 x 1038 and 5 x 1037 erg s–1. If we assume that they are at <10% Eddington, they have minimum masses of 20 and 4 M⊙ respectively. Furthermore, any LMXB exhibiting a low accretion rate power density spectrum at a luminosity > 5 x 1037 erg s–1 is likely to have a black hole primary.

JET FORMATION IN MICROQUASARS AND ACTIVE GALACTIC NUCLEI: MAGNETIC FIELD LIMITS

2008 ◽  
Vol 17 (10) ◽  
pp. 1931-1937
Author(s):  
M. M. KAUFMAN BERNADÓ ◽  
M. MASSI
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Accretion Rate ◽  
Plasma Pressure ◽  
X Ray ◽  
Mass Accretion Rate ◽  
Disk Material ◽  
The Magnetic Field

We introduce the use of a well-known parameter, the Alfvén Radius, R A , as a new tool to discern whether an X-ray binary system may undergo a microquasar phase, i.e. ejecting relativistic particles orthogonal to the accretion disk. We study what we call the basic condition, R A /R* = 1 in its dependency on the magnetic field strength and the mass accretion rate. With this basic condition we establish under which combination of parameters any class of accreting neutron stars could become a microquasar instead of confining disk-material down to the magnetic poles and creating the two emitting caps typical for an X-ray pulsar. In the case of black-hole accreting binaries we equate the magnetic field pressure to the plasma pressure in the last stable orbit (i.e. R A /R LSO = 1) and we get upper limits for the magnetic field strength as a function of the mass accretion rate and the black hole mass.

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