Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for a Sudden Magnetic Field Reconfiguration in SGR 1900+14   We report the detection of large flux changes in the persistent X-ray flux of
SGR 1900+14 during its burst active episode in 1998. Most notably, we find a
factor ~700 increase in the non-burst X-ray flux following the August 27th
flare, which decayed in time as a power-law. Our measurements indicate that the
pulse fraction remains constant throughout this decay. This suggests a global
flux enhancement as a consequence of the August 27th flare rather than
localized heating. While the persistent flux has since recovered to the
pre-outburst level, the pulse profile has not. The pulse shape changed to a
near sinusoidal profile within the tail of the August 27th flare (in
gamma-rays) and this effect has persisted for more than 1.5 years (in X-rays).
The results presented here suggest the magnetic field of the neutron star in
SGR 1900+14 was significantly altered (perhaps globally) during the giant flare
of August 27.

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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: physics
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The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: cs
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The categories of this paper are: hep-ph