Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Symbiotic stars in X-rays   Until recently, symbiotic binary systems in which a white dwarf accretes from
a red giant were thought to be mainly a soft X-ray population. Here we describe
the detection with the X-ray Telescope (XRT) on the Swift satellite of nine
white dwarf symbiotics that were not previously known to be X-ray sources and
one that had previously been detected as a supersoft X-ray source. The nine new
X-ray detections were the result of a survey of 41 symbiotic stars, and they
increase the number of symbiotic stars known to be X-ray sources by
approximately 30%. The Swift/XRT telescope detected all of the new X-ray
sources at energies greater than 2 keV. Their X-ray spectra are consistent with
thermal emission and fall naturally into three distinct groups. The first group
contains those sources with a single, highly absorbed hard component that we
identify as probably coming from an accretion-disk boundary layer. The second
group is composed of those sources with a single, soft X-ray spectral component
that probably originates in a region where low-velocity shocks produce X-ray
emission, i.e., a colliding-wind region.
  The third group consists of those sources with both hard and soft X-ray
spectral components. We also find that unlike in the optical, where rapid,
stochastic brightness variations from the accretion disk typically are not
seen, detectable UV flickering is a common property of symbiotic stars.
Supporting our physical interpretation of the two X-ray spectral components,
simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray
emission tend to have stronger UV flickering, which is usually associated with
accretion through a disk. To place these new observations in the context of
previous work on X-ray emission from symbiotic star.............

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The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: funct-an