Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chandra observations of the newly discovered magnetar Swift J1818.0-1607   Swift J1818.0-1607 is a new radio-loud magnetar discovered by the Swift Burst
Alert Telescope on 2020 March 12. It has a magnetic field B~2.5e14 G, spin-down
luminosity of 7.2e35 ergs/s, and characteristic age of ~470yr. Here we report
on the Chandra observations of Swift J1818.0-1607, which allowed for a
high-resolution imaging and spectroscopic study of the magnetar and its
environment. The 1-10 keV spectrum of the magnetar is best described by a
single blackbody model with a temperature of 1.2\pm0.1 keV and an unabsorbed
flux of 1.9e-11 ergs/cm^2/s. This implies an X-ray luminosity of ~9.6e34 ergs/s
and an efficiency of ~0.13 at a distance of 6.5 kpc. The Chandra image also
shows faint diffuse emission out to >10" from the magnetar, with its spectrum
adequately described by a powerlaw with a photon index of 2.0\pm0.5 and a
luminosity of ~8.1e33 ergs/s. The extended emission is likely dominated by a
dust scattering halo and future observations of the source in quiescence will
reveal any underlying compact wind nebula. We conclude that Swift J1818.0-1607
is a transient source showing properties between high-B pulsars and magnetars,
and could be powered at least partly by its high spin-down similar to the
rotation-powered pulsars.

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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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The categories of this paper are: hep-ex
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The categories of this paper are: q-bio
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The categories of this paper are: funct-an
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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: alg-geom
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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: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: stat