Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray outbursts from a new transient in NGC 55   We report the outbursts from a newly discovered X-ray transient in the
Magellanic-type, SB(s)m galaxy NGC 55. The transient source, XMMU
J001446.81-391123.48, was undetectable in the 2001 \xmm{} and 2004 \chandra{}
observations, but detected in a 2010 \xmm{} observation at a significance level
of $9\sigma$ in the 0.3--8 keV energy band. The \xmm{} spectrum is consistent
with a power law with photon index $\Gamma = 3.17^{+0.22}_{-0.20}$, but is
better fit with a $kT_{in} = 0.70\pm0.06$\,keV disk blackbody. The luminosity
was $\sim 10^{38}$\,erg\,s$^{-1}$, and the source displayed strong short-term
X-ray variability. These results, combined with the hardness ratios of its
emission, strongly suggest an X-ray binary nature for the source. The follow-up
studies with \swift{} XRT observations revealed that the source exhibited
recurrent outbursts with period about a month. The XRT spectra can be described
by a power law ($\Gamma\sim 2.5$--2.9) or a disk blackbody ($kT_{in}\sim
0.8$--1.0\,keV), and the luminosity was in a range of
10$^{38}$--10$^{39}$\,erg\,s$^{-1}$, with no evidence showing any significant
changes of the spectral parameters in the observations. Based on the X-ray
spectral and temporal properties, we conclude that XMMU J001446.81-391123.48 is
a new transient X-ray binary in NGC 55, which possibly contains a black hole
primary.

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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio
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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin
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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: hep-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex