Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modulation of AGN gamma rays by interaction with X-rays from an
  accretion disk hot spot   We have developed a model for the variability of gamma ray emission in jets
of active galactic nuclei in which the variability arises as a result of
photon-photon pair production interactions with X-rays emitted by a hot spot in
the inner part of the accretion disk. As the hot spot orbits around the central
engine, the amount of absorption varies periodically. Our model may account for
the observed variability of TeV emission from Markarian 421 and other blazars
detected by the EGRET instrument on the Compton Gamma Ray Observatory, as well
as correlated variations of X-ray and TeV gamma flux from Markarian 421.
Quasi-periodic variations observed in Markarian 421 enable us to place an upper
limit on the black hole mass of (2-30) times 10^8 solar masses.

33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
23
The categories of this paper are: solv-int