Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High Energy Radiation from Neutron Star Binaries   This paper surveys our current knowledge of the hard X-ray emission
properties of old accreting neutron stars in low mass X-ray binaries. Hard
X-ray components extending up to energies of a few hundred keV have been
clearly detected in sources of both the Atoll and Z classes. The presence and
characteristics of these hard components are discussed in relation to source
properties and state. An overall anticorrelation between the fraction
luminosity in hard X-rays and mass accretion rate is apparent over different
sources spanning a large range of luminosities as well as individual source
undergoing state changes. Evidence for a second, yet unknown, parameter
controlling the hard X-ray emission is emerging. We draw a parallel with the
spectral properties of X-ray binaries hosting a stellar mass accreting black
hole, and conclude that, at a merely phenomenological level, there appears to
be a close analogy between the spectral properties of black hole candidates in
their high and intermediate states and Z-sources. We briefly mention models
that have been proposed for the hard X-ray emission of neutron star low mass
X-ray binaries and comment on perspectives in the INTEGRAL era.

1
The categories of this paper are: cs
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: eess
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an