Role of Shocked Accretion Flows in Regulating the Quasi-periodic Oscillation of Galactic Black Hole Candidates

2003 ◽  
Vol 588 (2) ◽  
pp. L89-L92 ◽  
Author(s):  
Tapas K. Das
Keyword(s):  
Black Hole ◽  
Periodic Oscillation ◽  
Quasi Periodic Oscillation ◽  
Accretion Flows ◽  
Galactic Black Hole ◽  
Black Hole Candidates

THE EFFECTS OF DIFFERENT PERTURBATIONS ON THE DYNAMICS OF THE ACCRETION DISK AROUND THE BLACK HOLE

2007 ◽  
Vol 22 (10) ◽  
pp. 1875-1898 ◽  
Author(s):  
ORHAN DÖNMEZ
Keyword(s):  
Shock Wave ◽  
Black Hole ◽  
Shock Waves ◽  
Accretion Disk ◽  
Periodic Oscillation ◽  
Single Star ◽  
Special Cases ◽  
Galactic Black Hole ◽  
General Relativistic ◽  
Armed Spiral

We investigate the special cases of the formation of shocks in the accretion disks around the nonrotating (Schwarzschild) black holes in cases where one or few stars perturb the disk. We model the structure of disk with a 2D fully general relativistic hydrodynamic code and investigate a variety of cases in which the stars interacting with the disk are captured at various locations. We have found the following results: (1) if the stars perturb the disk at nonsymmetric locations, a moving one-armed spiral shock wave is produced and it destroys the disk eventually; (2) if the disk is perturbed by a single star located close to the black hole, a standing shock wave is produced while the disk becomes an accretion tori; (3) if the disk is perturbed by stars at symmetric locations, moving two-armed spiral shock waves are produced while the disk reaches a steady state; (4) continuous injection of matter into the stable disk produces a standing shock wave behind the black hole. Our outcomes reinforce the view that different perturbations on the stable accretion disk carry out different types of shock waves which produce Quasi-Periodic Oscillation (QPO) phenomena in galactic black hole candidates and it is observed as a X-ray.

Gamma-ray monitoring of AGN and galactic black hole candidates by the gamma-ray observatory

1992 ◽  
Author(s):  
Wm. A. Wheaton ◽  
James C. Ling ◽  
R. T. Skelton ◽  
Alan Harmon ◽  
Gerald J. Fishman ◽  
...  
Keyword(s):  
Black Hole ◽  
Gamma Ray ◽  
Galactic Black Hole ◽  
Black Hole Candidates

scholarly journals Numerical Simulations of Advective Flows Around Black Holes

1997 ◽  
Vol 163 ◽  
pp. 690-691
Author(s):  
Sandip K. Chakrabarti ◽  
D. Ryu ◽  
D. Molteni ◽  
H. Sponholz ◽  
G. Lanzafame ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Periodic Oscillation ◽  
Compact Objects ◽  
Advective Flow ◽  
Sonic Point ◽  
Quasi Periodic Oscillation ◽  
Accretion Flows ◽  
Advective Flows ◽  
Cooling Effects ◽  
Implicit Code

Observational results of compact objects are best understood using advective accretion flows (Chakrabarti, 1996, 1997). We present here the results of numerical simulations of all possible types of such flows.Two parameter (specific energy ε and specific angular momentum λ) space of solutions of inviscid advective flow is classified into ‘SA’ (shocks in accretion), ‘NSA’ (no shock in accretion), ‘I’ (inner sonic point only), ‘O’ (outer sonic point only) etc. (Fig. 1 of Chakrabarti, 1997 and references therein). Fig. 1a shows examples of solutions (Molteni, Ryu & Chakrabarti, 1996; Eggum, in preparation) from ‘SA’, ‘I’ and ‘O’ regions where we superpose analytical (solid) and numerical simulations (short dashed curve is with SPH code and medium dashed curve is with TVD code; very long dashed curve is with explicit/implicit code). The agreement is excellent. In presence of cooling effects, shocks from ‘SA’ oscillate (Fig. 1b) when the cooling timescale roughly agrees with postshock infall time scale (Molteni, Sponholz & Chakrabarti, 1996). The solid, long dashed and short dashed curves are drawn for T1/2 (bremsstrahlung), T0.4 and T0.75 cooling laws respectively. In the absence of steady shock solutions, shocks for parameters from ‘NSA’ oscillate (Fig. 2) even in the absence of viscosity (Ryu et al. 1997). The oscillation frequency and amplitude roughly agree with those of quasi-periodic oscillation of black hole candidates. When the flow starts from a cool Keplerian disk, it simply becomes sub-Keplerian before it enters through the horizon. Fig. 3a shows this behaviour where the ratio of λ/λKeplerian is plotted. When the flow deviates from a hot Keplerian disk, it may develop a standing shock as well (Fig. 3b) (Molteni et al. 1996).

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