Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectral Properties of X-ray Binaries in Centaurus A   We present a spectral investigation of X-ray binaries in NGC 5128 (Cen A),
using six 100 ks Chandra observations taken over two months in 2007. We divide
our sample into thermally and non-thermally dominated states based on the
behavior of the fitted absorption column, and present the spectral parameters
of sources with L >2x10^37 erg/s. The majority of sources are consistent with
being neutron star low mass X-ray binaries (NS LMXBs) and we identify three
transient black hole (BH) LMXB candidates coincident with the dust lane, which
is the remnant of a small late-type galaxy. Our results also provide tentative
support for the apparent `gap' in the mass distribution of compact objects
between ~2-5 Msol.
  We propose that BH LMXBs are preferentially found in the dust lane, and
suggest this is because of the younger stellar population. The majority
(~70-80%) of potential Roche-lobe filling donors in the Cen A halo are >12 Gyr
old, while BH LMXBs require donors >1 Msol to produce the observed peak
luminosities. This requirement for more massive donors may also explain recent
results that claim a steepening of the X-ray luminosity function with age at Lx
>= 5x10^38 erg/s for the XB population of early-type galaxies; for older
stellar populations, there are fewer stars >1 Msol, which are required to form
the more luminous sources.

1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: math
11
The categories of this paper are: hep-lat
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The categories of this paper are: physics