1994/09/09 by Xingming Chen, Ronald E. Taam · 2 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Dust and Plasma Wave Phenomena #astro-ph
paper · pdf · doi:10.1086/175360
Submitted to ApJ, June 1994. PS file, 20 Pages; 9 Figs available upon request. Report#1234567890
arxiv created 1994/09/09 · openalex publication_date 1995/03/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The global nonlinear time-dependent evolution of the inertial-acoustic mode instability in accretion disks surrounding black holes has been investigated. The viscous stress is assumed to be proportional to the gas pressure only, i.e. , τ = - α pg. It is found that an oscillatory instability exists in the inner regions of disks (r < 10 rg, where rg is the Schwarzschild radius) for sufficiently large α (\gapprox 0.2), and for mass accretion rates less than about 0.3 times the Eddington value. The variations of the integrated bolometric luminosity from the disk, Δ L/L, are less than 3%. A power spectrum analysis of these variations reveals a power spectrum which can be fit to a power law function of the frequency P ∝ f-γ, with index γ ∼ 1.4-2.3 and a low frequency feature at about 4 Hz in one case. In addition, a narrow peak centered at a frequency corresponding to the maximum epicyclic frequency of the disk at ∼ 100-130 Hz and its first harmonic is also seen. The low frequency modulations are remarkably similar to those observed in black hole candidate systems. The possible existence of a scattering corona in the inner region of the disk and/or to other processes contributing to the power at high frequencies in the inner region of the accretion disk may make the detection of the high frequency component difficult.