著者

Uchida Hiroyuki Yamaguchi Hiroya Koyama Katsuji

出版者

IOP Publishing

雑誌

The Astrophysical Journal (ISSN:0004637X)

巻号頁・発行日

vol.771, no.1, 2013-07-01

被引用文献数

32

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藤原定家の超新星は非対称爆発をした -X線天文衛星「すざく」が明らかにした標準光源の「ゆがんだ」形状-. 京都大学プレスリリース. 2013-07-02.

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.

著者

Koyama Katsuji Hyodo Yoshiaki Inui Tatsuya NAKAJIMA Hiroshi MATSUMOTO Hironori TSURU Takeshi Go TAKAHASHI Tadayuki MAEDA Yoshitomo YAMAZAKI Noriko Y. MURAKAMI Hiroshi YAMAUCHI Shigeo TSUBOI Yohko SENDA Atsushi KATAOKA Jun TAKAHASHI Hiromitsu HOLT Stephen S. BROWN Gregory V.

出版者

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.59, no.1, pp.S245-S255, 2007-01-31

被引用文献数

16 129

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We have observed the diffuse X-ray emission from the Galactic Center (GC) using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy resolution and the low-background orbit provided excellent spectra of the GC diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the energy of K-shell transitions of iron and nickel. The most pronounced features are Fe I Kα at 6.4 keV and K-shell absorption edge at 7.1 keV, which are from neutral and/or low ionization states of iron, and the K-shell lines at 6.7 keV and 6.9 keV from He-like (Fe XXV Kα) and hydrogenic (Fe XXVI Lyα) ions of iron. In addition, Kα lines from neutral or low ionization nickel (Ni I Kα) and He-like nickel (Ni XXVII Kα), Fe I Kβ, Fe XXV Kβ, Fe XXVI Lyβ, Fe XXV Kγ and FeXXVI Lyγ were detected for the first time. The line center energies and widths of Fe XXV Kα and Fe XXVI Lyα favor a collisional excitation plasma for the origin of the GCDX. The electron temperature determined from the line flux ratio of Fe XXV Kα/Fe XXV Kβ is similar to the ionization temperature determined from that of Fe XXV Kα/Fe XXVI Lyα. Thus it would appear that the GCDX plasma is close to ionization equilibrium. The 6.7 keV flux and temperature distribution to the galactic longitude is smooth and monotonic, in contrast to the integrated point source flux distribution. These facts support the hypothesis that the GCDX is truly diffuse emission rather than the integration of the outputs of a large number of unresolved point sources. In addition, our results demonstrate that the chemical composition of Fe in the interstellar gas near the GC is constrained to be about 3.5 times solar abundance.