Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gamma-Ray Spectral Characteristics of Thermal and Non-Thermal Emission
  from Three Black Holes   Cygnus X-1 and the gamma-ray transients GROJ0422+32 and GROJ1719-24 displayed
similar spectral properties when they underwent transitions between the high
and low gamma-ray (30 keV to few MeV) intensity states. When these sources were
in the high gamma-ray intensity state (gamma-2, for Cygnus X-1), their spectra
featured two components: a Comptonized shape below 200-300 keV with a soft
power-law tail (photon index >3) that extended to ~1 MeV or beyond. When the
sources were in the low-intensity state (gamma-0, for Cygnus X-1), the
Comptonized spectral shape below 200 keV typically vanished and the entire
spectrum from 30 keV to ~1 MeV can be characterized by a single power law with
a relatively harder photon index ~2-2.7. Consequently the high- and
low-intensity gamma-ray spectra intersect, generally in the ~400 keV - 1 MeV
range, in contrast to the spectral pivoting seen previously at lower (~10 keV)
energies. The presence of the power-law component in both the high- and
low-intensity gamma-ray spectra strongly suggests that the non-thermal process
is likely to be at work in both the high and the low-intensity situations. We
have suggested a possible scenario (Ling & Wheaton, 2003), by combining the
ADAF model of Esin et al. (1998) with a separate jet region that produces the
non-thermal gamma-ray emission, and which explains the state transitions. Such
a scenario will be discussed in the context of the observational evidence,
summarized above, from the database produced by EBOP, JPL's BATSE earth
occultation analysis system.

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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-th
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph