Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Large-Area Cross-Correlation Study of High Galactic Latutude Soft and
  Hard X-ray Skies   We have made cross-correlation analyses of (2 -- 15 keV) HEAO A2 and 1 keV
ROSAT PSPC All-Sky Survey maps over a selected area ($\sim$ 4000 deg$^2$) with
high galactic latitude (b>40 deg). We have calculated the correlations for the
bright ROSAT sources and residual background separately with the \HEAO A2 TOT
(2 -- 10 keV) and HRD (5 -- 15 keV) maps. The amplitude of the bright \ROSAT
source -- A2 CCFs are consistent with expectations from model populations of
AGNs and clusters of galaxies, which emit in both bands. However, the residual
ROSAT background -- A2 CCFs amplitude at zero degree are about a factor of
three larger than that expected from the model populations. Our soft-hard
zero-lag and angular CCF results have been compared with the 1 keV
auto-correlation function (ACF) found by Soltan et al. (1995) for the same
ROSAT data. Their significant angular CCF at a scale of < 5 deg is of an
unknown origin and it could represent a new class of cosmic X-ray sources. If
this 1 keV ACF has a hot plasma spectrum with kT\sim 2 keV, contribution of
this component is consistent with both our zero-lag CCF in excess of the
population synthesis model prediction and the upper-limit to the angular CCF at
\theta \sim 2.5 deg. On the other hand, if this component has a lower
temperature or a steeper spectrum, a major modification to the population
synthesis model and/or an introduction of new classes would be needed.

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The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: cond-mat