Variability of accretion disks surrounding black holes: The role of inertial-acoustic mode instabilities

Xingming Chen*, Ronald E. Taam

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


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 = -αpg. It is found that an oscillatory nonsteady behavior exists in the inner regions of disks (r < 10rg, where rg is the Schwarzschild radius) for sufficiently large α (≳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, ΔL/L, are less than 3%. A power spectrum analysis of these variations reveals a power spectrum which can be fitted to a power-law function of the frequency P ∝ f, 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 correuting to the power at high frequencies in the inner region of the accretion disk may make the detection of the high-frequency component difficult.

Original languageEnglish (US)
Pages (from-to)354-360
Number of pages7
JournalAstrophysical Journal
Issue number1
StatePublished - Mar 1 1995


  • Accretion, accretion disks
  • Black hole physics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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