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Yoshitomo Maeda, Yasunobu Uchiyama, Aya Bamba, Hiroko Kosugi, Hiroshi Tsunemi, Eveline A. Helder, Jacco Vink, Natsuki Kodaka, Yukikatsu Terada, Yasushi Fukazawa, Junko Hiraga, John P. Hughes, Motohide Kokubun, Tomomi Kouzu, Hironori Matsumoto, Emi Miyata, Ryoko Nakamura, Shunsaku Okada, Kentaro Someya, Toru Tamagawa, Keisuke Tamura, Kohta Totsuka, Yohko Tsuboi, Yuichiro Ezoe, Stephen S. Holt, Manabu Ishida, Tsuneyoshi Kamae, Robert Petre, Tadayuki Takahashi, Suzaku X-Ray Imaging and Spectroscopy of Cassiopeia A, Publications of the Astronomical Society of Japan, Volume 61, Issue 6, 25 December 2009, Pages 1217–1228, https://doi.org/10.1093/pasj/61.6.1217
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Abstract
Suzaku X-ray observations of a young supernova remnant, Cassiopeia A, were carried out. K-shell transition lines from highly ionized ions of various elements were detected, including Chromium (Cr-K|$\alpha $| at 5.61 keV). The X-ray continuum spectra were modeled in the 3.4–40 keV band, summed over the entire remnant, and were fitted with a simplest combination of the thermal bremsstrahlung and the non-thermal cut-off power-law models. The spectral fits with this assumption indicate that the continuum emission is likely to be dominated by non-thermal emission with a cut-off energy at |$> $|1 keV. The thermal-to-nonthermal fraction of the continuum flux in the 4–10 keV band is best estimated as |$\sim $|0.1. Non-thermal-dominated continuum images in the 4–14 keV band were made. The peak of the non-thermal X-rays appears at the western part. The peak position of the TeV |$\gamma$|-rays measured with HEGRA and MAGIC is also shifted at the western part with the 1-sigma confidence. Since the location of the X-ray continuum emission was known to be presumably identified with the reverse shock region, the possible keV–TeV correlations give a hint that the accelerated multi-TeV hadrons in Cassiopeia A are dominated by heavy elements in the reverse shock region.
