Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Thorough Look at the Photoionized Wind and Absorption Dips in the
  Cygnus X-1 / HDE 226868 X-ray Binary System   We present results from simultaneous observations of the high-mass X-ray
binary system Cygnus X-1 / HDE 226868 with Suzaku, Chandra-HETGS, XMM-Newton,
RXTE, INTEGRAL, and Swift in 2008 April. Performed shortly after orbital phase
0, when our line of sight to the black hole passes through the densest part of
the O-star's wind, these obervations show common transient absorption dips in
the soft X-ray band. For the first time, however, we detect a simultaneous
scattering trough in the hard X-ray light curves. The more neutral clump is
thus only the core of a larger ionized blob, which contains a significant
fraction of the total wind mass. The diluted wind outside of these clumps is
almost completely photoionized.

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The categories of this paper are: dg-ga
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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The categories of this paper are: math