Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Accretion Disc Turbulence and the X-Ray Power Spectra of Black Hole High
  States   The high state of black hole candidates is characterized by a quasi- thermal
emission component at $kT \sim 1$ keV. In addition, this state tends to have
very low variability which indicates that it is relatively stable, at least on
{\it short} time scales. Most models of the high state imply that the bulk of
the emission comes from an optically thick accretion disc; therefore, this
state may be an excellent laboratory for testing our ideas about the physics of
accretion discs. In this work we consider the implications of assuming that
accretion disc viscosity arises from some form of turbulence. Specifically, we
consider the simple case of three dimensional hydrodynamic turbulence. It is
found that the coupling of such turbulence to acoustic modes in the disc can
alter the disc emission. We calculate the amplitude and frequencies of this
modulation, and we express our results in terms of the X-ray power spectral
density. We compare our calculations with observations of the black hole
candidate GS 1124-683, and show that for certain parameters we can reproduce
some of the high frequency power. We then briefly explore mechanisms for
producing the low frequency power, and note the difficulty that a single
variability mechanism has in reproducing the full range of observed
variability. In addition, we outline ways in which future spacecraft missions
-- such as USA and XTE -- can further constrain our model, especially at
frequencies above $\sim 10^2$ Hz.

14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin