Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: XMM-Newton and INTEGRAL study of the SFXT IGR J18483-0311 in quiescence:
  hint of a cyclotron emission feature?   We report the results from archival XMM-Newton and INTEGRAL observations of
the Supergiant Fast X-ray Transient (SFXT) IGR J18483-0311 in quiescence. The
18-60 keV hard X-ray behaviour of the source is presented here for the first
time, it is characterized by a spectral shape ($\Gamma$ about 2.5) similar to
that during outburst activity and the lowest measured luminosity level is about
10^34 erg s^-1. The 0.5-10 keV luminosity state, measured by XMM-Newton during
the apastron passage, is about one order of magnitude lower and it is
reasonably fitted by an absorbed black body model yielding parameters
consistent with previous measurements. In addition, we find evidence (about 3.5
sigma significance) of an emission-like feature at about 3.3 keV in the
quiescent 0.5-10 keV source spectrum. The absence of any known or found
systematic effects, which could artificially introduce the observed feature,
give us confidence about its non-instrumental nature. We show that its physical
explanation in terms of atomic emission line appears unlikely and conversely we
attempt to ascribe it to an electron cyclotron emission line which would imply
a neutron star magnetic field of the order of about 3x10^11 G. Importantly,
such direct estimation is in very good agreement with that independently
inferred by us in the framework of accretion from a spherically symmetric
stellar wind. If firmly confirmed by future longer X-ray observations, this
would be the first detection ever of a cyclotron feature in the X-ray spectrum
of a SFXT, with important implications on theoretical models.

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The categories of this paper are: math
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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: gr-qc
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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: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: cs
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The categories of this paper are: stat
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: q-bio