Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The X/gamma-ray spectral properties of NGC 7172   We present a combined, non-simultaneous, ASCA GIS and CGRO OSSE spectrum of
the Seyfert 2 galaxy, NGC 7172, and make broad band spectral fits. The only
Seyfert 2 galaxy previously studied over such a broad band is NGC 4945. We find
that the most probable model for the data is a power law with an exponential
cut-off being affected by a neutral absorber. The best fit parameters are found
to be $\Gamma = 1.47 \pm 0.15$ and $\NH = (7.8 \pm 0.6) 10^{22}$ cm$^{-2}$. The
spectral index of the underlying power law of NGC 7172 has therefore varied
from 1.8 to 1.5 since the Ginga observations in 1989. For this simple model the
e-folding energy at $88^{+65}_{-28}$ keV is relatively well constrained. The
observed flux in the 2-10 keV range is $F_{2-10}=4.7 10^{-11}$ erg cm$^{-2}$
s$^{-1}$, which corresponds to a small increase since the Ginga measurement in
October 1989.

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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: cs
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The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: bayes-an
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The categories of this paper are: physics