Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fourier-phase analysis of the orbiting bright-spot model for AGN
  variability   Fourier power spectra and phases of a signal from a large number of radiating
sources orbiting around a black hole are investigated. It is assumed that the
individual sources (bright spots) are located in an accretion disc and their
lifetime exceeds the corresponding orbital period. This model is relevant for
the short-time X-ray variability of active galactic nuclei. Previous works on
this subject were mostly concentrated on temporal characteristics and power
spectra of observed light curves. In our present contribution, Fourier phases
are brought into consideration and studied systematically for a broad range of
input parameters. In particular, conditions for the phase coherence are
discussed. It is shown that one can discriminate between the two classes of
models which are currently under consideration--orbital motion of a large
number of sources versus short-lived independent flares--although parameters of
the model are not completely arbitrary. It is also shown that predicted power
spectra depend rather strongly on the spot distribution across the disk
surface. We conclude that the orbital motion of the spots cannot be the only
reason for the source fluctuations, but it certainly influences observational
properties of the source intrinsic variability.

37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th