Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The X-ray outburst of the Galactic Center magnetar over six years of
  Chandra observations   The magnetar SGR J1745-2900 discovered at parsecs distance from the Milky Way
central black hole, Sagittarius A*, represents the closest pulsar to a
supermassive black hole ever detected. Furthermore, its intriguing radio
emission has been used to study the environment of the black hole, as well as
to derive a precise position and proper motion for this object. The discovery
of SGR J1745-2900 has opened interesting debates about the number, age and
nature of pulsars expected in the Galactic center region. In this work, we
present extensive X-ray monitoring of the outburst of SGR J1745-2900 using the
Chandra X-ray Observatory, the only instrument with the spatial resolution to
distinguish the magnetar from the supermassive black hole (2.4" angular
distance). It was monitored from its outburst onset in April 2013 until August
2019, collecting more than fifty Chandra observations for a total of more than
2.3 Ms of data. Soon after the outburst onset, the magnetar emission settled
onto a purely thermal emission state that cooled from a temperature of about
0.9 to 0.6 keV over 6 years. The pulsar timing properties showed at least two
changes in the period derivative, increasing by a factor of about 4 during the
outburst decay. We find that the long-term properties of this outburst
challenge current models for the magnetar outbursts.

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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
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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: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: patt-sol
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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: cs