Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First Detection of Ar-K Line Emission from the Cygnus Loop   We observed the Cygnus Loop with XMM-Newton (9 pointings) and Suzaku (32
pointings) between 2002 and 2008. The total effective exposure time is 670.2
ks. By using all of the available data, we intended to improve a
signal-to-noise ratio of the spectrum. Accordingly, the accumulated spectra
obtained by the XIS and the EPIC show some line features around 3 keV that are
attributed to the S He$\beta$ and Ar He$\alpha$ lines, respectively. Since the
Cygnus Loop is an evolved ($\sim$10,000 yr) supernova remnant whose temperature
is relatively low ($<$1 keV) compared with other young remnants, its spectrum
is generally faint above 3.0 keV, no emission lines, such as the Ar-K line have
ever been detected. The detection of the Ar-K line is the first time and we
found that its abundance is significantly higher than that of the solar value;
9.0$^{+4.0}_{-3.8}$ and 8.4$^{+2.5}_{-2.7}$ (in units of solar), estimated from
the XIS and the EPIC spectra, respectively. We conclude that the Ar-K line
originated from the ejecta of the Cygnus Loop. Follow-up X-ray observations to
tightly constrain the abundances of Ar-rich ejecta will be useful to accurately
estimate the progenitor's mass.

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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
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The categories of this paper are: comp-gas
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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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: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ph
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The categories of this paper are: mtrl-th