Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: CXOM31 J004253.1+411422: The first ultra-luminous X-ray transient in M
  31   We seek clarification of the nature of X-ray sources detected in M 31. Here
we focus on CXOM31 J004253.1+411422, the brightness of which suggests that it
belongs to the class of ultraluminous X-ray sources. We determine the X-ray
properties of sources detected in the XMM-Newton Chandra monitoring program. We
investigate spectral properties and search for periodic or quasi-periodic
oscillations. A multi-component model is applied to the spectra obtained from
XMM-Newton data to evaluate the relative contributions from thermal and
non-thermal emission. The time dependence of this ratio is evaluated over a
period of forty days. We simultaneously fit data from XMM-Newton EPIC-pn, MOS1
and MOS2 detectors with (non-thermal) powerlaw and (thermal) multicolored
blackbody. The X-ray spectrum is best fit by the combination of a thermal
component with kT ~ 1 keV and a powerlaw component with photon index
approximately 2.6. From combined analysis of Chandra, Swift and XMM-Newton
data, the unabsorbed total luminosity of this source decreases from ~ 3.8 x
10^{39} erg s^{-1} in the first observation to ~ 0.5 x 10^{39} ergs s^{-1} over
a period of three months. The decay closely follows an exponential decline with
a time constant of 32 days. The source spectrum evolves significantly,
exhibiting a faster decline of the thermal component. We do not find evidence
of any significant temporal features in the power density spectrum. The
presence of a thermal component at kT ~ 1 keV in conjunction with a non-thermal
high energy tail, is also consistent with spectral properties of other ULXs in
the "high state". Our analysis indicates that the underlying source of this
first ULX in M~31 is a black hole of mass, M > 13 M_{sun}, accreting near the
Eddington limit, that underwent a transient outburst followed by an exponential
decay reminiscent of transients associated with galactic X-ray novae.

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The categories of this paper are: nlin
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-bio
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: quant-ph