Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: INTEGRAL broadband spectroscopy of Vela X-1   The wind-accreting X-ray binary pulsar and cyclotron line source Vela X-1 has
been observed extensively during INTEGRAL Core Program observations of the Vela
region in June-July and November-December 2003. In the latter set of
observations the source showed intense flaring -- see also Staubert et al.
(2004), these proceedings.
  We present early results on time averaged and time resolved spectra, of both
epochs of observations. A cyclotron line feature at ~53 keV is clearly detected
in the INTEGRAL spectra and its broad shape is resolved in SPI spectra. The
remaining issues in the calibration of the instruments do not allow to resolve
the question of the disputed line feature at 20-25 keV.
  During the first main flare the average luminosity increases by a factor of
\~10, but the spectral shape remains very similar, except for a moderate
softening.

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The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
34
The categories of this paper are: chem-ph
3
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: comp-gas
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The categories of this paper are: cond-mat
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: nlin