Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Properties Of The Hard X-ray Emission From The Black Hole Candidates:
  Cygnus X-1 And 1E1740.7-2942   The entire dataset of the GRANAT/SIGMA observations of Cyg X-1 and
1E1740.7-2942 in 1990-1994 was analyzed in order to search for correlations
between primary observational characteristics of the hard X-ray (40-200 keV)
emission - hard X-ray luminosity, hardness of the spectrum (quantified in terms
of the best-fit thermal bremsstrahlung temperature kT) and the RMS of
short-term flux variations. Although no strict point-to-point correlations were
detected certain general tendencies are evident. It was found that for Cyg X-1
the spectral hardness is in general positively correlated with relative
amplitude of short-term variability. The correlation of similar kind was found
for X-ray transient GRO J0422+32 (X-ray Nova Persei 1992) and recently for
GX339-4. For both sources approximate correlation between kT and L_X was found.
At low hard X-ray luminosity - below 10E37 erg/sec - the kT increases with
increase of L_X. At higher luminosity the spectral hardness depends weaker or
does not depend at all on the hard X-ray luminosity. The low luminosity end of
these approximate correlations (low kT and low RMS) corresponds to extended
episodes of very low hard X-ray flux occurred for both sources during SIGMA
observations.

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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: comp-gas
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The categories of this paper are: stat
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
32
The categories of this paper are: atom-ph