Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On an excitation mechanism for trapped inertial waves in discs around
  black holes   According to one model, high-frequency quasi-periodic oscillations (QPOs) can
be identified with inertial waves, trapped in the inner regions of accretion
discs around black holes due to relativistic effects. In order to be detected,
their amplitudes need to reach large enough values via some excitation
mechanism. We work out in detail a non-linear coupling mechanism suggested by
Kato, in which a global warping or eccentricity of the disc has a fundamental
role. These large-scale deformations combine with trapped modes to generate
`intermediate' waves of negative energy that are damped as they approach either
their corotation resonance or the inner edge of the disc, resulting in
amplification of the trapped waves. We determine the growth rates of the
inertial modes, as well as their dependence on the spin of the black hole and
the properties of the disc. Our results indicate that this coupling mechanism
can provide an efficient excitation of trapped inertial waves, provided the
global deformations reach the inner part of the disc with non-negligible
amplitude.

23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc