Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The X-ray properties of the dwarf Magellanic-type galaxy NGC 55   We present an analysis of the X-ray properties of the Magellanic-type galaxy
NGC 55 based on two contiguous XMM-Newton observations. We detect a total of
137 X-ray sources in the field of view, 42 of which are located within the
optical confines of the galaxy. On the basis of X-ray colour classification and
after correcting for background objects, we conclude that our source sample
includes ~ 20 X-ray binaries, 5 supernova remnants and 7 very soft sources
(including 2 good candidate supersoft sources) associated with NGC 55. Detailed
spectral and timing analysis was carried out on 4 of the brightest X-ray
sources. One of these objects is identified with a Galactic foreground star and
is a possible new RS CVn system. The other three are consistent with accreting
X-ray binaries, though further evidence of short term variability is required
to confirm this. We also find evidence of an underlying component, which is
concentrated on the bar region but has an extent of at least 6' (3 kpc) in the
plane of the galaxy and +/- 1' (+/- 500 pc) perpendicular to it. This emission
is best fitted by a thermal plasma plus power-law model but with high intrinsic
absorption consistent with its location in the central disc of the galaxy. We
interpret the soft component as diffuse thermal emission linked to regions of
current star formation, whilst the hard power-law component may originate in
unresolved X-ray binary sources. The intrinsic luminosity of this residual disc
emission may exceed Lx ~ 6e38 ergs/s (0.3-6 keV). A comparison with other
Magellanic systems confirms that, in terms of both its discrete X-ray source
population and its extended emission, NGC 55 has X-ray properties which are
typical of its class.

1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci