著者

Tamagawa Toru Hayato Asami Nakamura Satoshi TERADA Yukikatsu BAMBA Aya HIRAGA Junko S. HUGHES John P. HWANG Una KATAOKA Jun KINUGASA Kenzo KUNIEDA Hideyo TANAKA Takaaki TSUNEMI Hiroshi UENO Masaru HOLT Stephen S. KOKUBUN Motohide MIYATA Emi SZYMKOWIAK Andrew TAKAHASHI Tadayuki TAMURA Keisuke UENO Daisuke MAKISHIMA Kazuo

出版者

社団法人日本天文学会

雑誌

PASJ : publications of the Astronomical Society of Japan (ISSN:00046264)

巻号頁・発行日

vol.61, no.1, pp.S167-S174, 2009-01-30

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Tycho's supernova remnant was observed by the XIS and HXD instruments onboard the Suzaku satellite on 2006 June 26-29 for 92 ks. The spectrum up to 30 keV was well fitted with a two-component model, consisting of a power-law with photon index of 2.7 and a thermal bremsstrahlung model with temperature of 4.7 keV. The former component can alternatively be modeled as synchrotron emission from a population of relativistic electrons with an estimated roll-off energy of around 1 keV. In the XIS spectra, in addition to the prominent Fe K_alpha line (6.445 keV), we observe for the first time significant K_alpha line emission from the trace species Cr and Mn at energies of 5.48 keV and 5.95 keV, respectively. Faint K_beta lines from Ca (4.56 keV) and Fe (7.11 keV) are also seen. The ionization states of Cr and Mn, based on their line centroids, are estimated to be similar to that of Fe K_alpha (Fe XV or XVI).

著者

Bamba Aya Yamazaki Ryo Yoshida Tatsuo Terasawa Toshio Koyama Katsuji

出版者

University of Chicago Press

雑誌

Astrophysical Journal (ISSN:0004637X)

巻号頁・発行日

vol.621, no.2, pp.793-802, 2005-03

被引用文献数

13 218

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The outer shells of young supernova remnants (SNRs) are the most plausible acceleration sites of high-energy electrons with the diffusive shock acceleration (DSA) mechanism. We studied spatial and spectral properties close to the shock fronts in four historical SNRs (Cas A, Kepler's remnant, Tycho's remnant, and RCW86) with excellent spatial resolution of Chandra. In all of the SNRs, hard X-ray emissions were found on the rims of the SNRs, which concentrate in very narrow regions ( so-called filaments); apparent scale widths on the upstreamside are below or on the order of the point-spread function of Chandra, while they are 0.'' 5 - 40 '' (0.01 - 0.4 pc) on the downstream side with most reliable distances. The spectra of these filaments can be fitted with both thermal and nonthermal ( power law and SRCUT) models. The former requires unrealistic high temperature (greater than or similar to 2 keV) and low abundances (less than or similar to 1 solar) for emission from young SNRs and may be thus unlikely. The latter reproduces the spectra with best-fit photon indices of 2.1 - 3.8, or roll-off frequencies of (0.1 28) x 10(17) Hz, which reminds us of the synchrotron emission from electrons accelerated via DSA. We consider various physical parameters as functions of the SNR age, including the previous results on SN 1006; the filament width on the downstream side increases with the SNR age, and the spectrum becomes softer, keeping a nonthermal feature. It was also found that a function, that is, the roll-off frequency divided by the square of the scale width on the downstream side, shows negative correlation with the age, which might provide us some information on the DSA theory.