Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Monitoring Supergiant Fast X-ray Transients with Swift. Results from the
  first year   Swift has allowed the possibility to give Supergiant Fast X-ray Transients
(SFXTs), the new class of High Mass X-ray Binaries discovered by INTEGRAL, non
serendipitous attention throughout all phases of their life. We present our
results based on the first year of intense Swift monitoring of four SFXTs, IGR
J16479-4514, XTE J1739-302, IGR J17544-2619 and AX J1841.0-0536. We obtain the
first assessment of how long each source spends in each state using a
systematic monitoring with a sensitive instrument. The duty-cycle of inactivity
is 17, 28, 39, 55% (5% uncertainty), for IGR J16479-4514, AX J1841.0-0536, XTE
J1739-302, and IGR J17544-2619, respectively, so that true quiescence is a rare
state. This demonstrates that these transients accrete matter throughout their
life at different rates. AX J1841.0-0536 is the only source which has not
undergone a bright outburst during our campaign. Although individual sources
behave somewhat differently, common X-ray characteristics of this class are
emerging such as outburst lengths well in excess of hours, with a multiple
peaked structure. A high dynamic range (including bright outbursts) of 4 orders
of magnitude has been observed. We performed out-of-outburst intensity-based
spectroscopy. Spectral fits with an absorbed blackbody always result in
blackbody radii of a few hundred meters, consistent with being emitted from a
small portion of the neutron star surface, very likely the neutron star polar
caps. We also present the UVOT data of these sources. (Abridged)

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The categories of this paper are: nucl-ex
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The categories of this paper are: q-bio
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The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: math
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ex