Yoshida, A.,
Namiki, M.,
Otani, C.,
河合 誠之,
Murakami, T.,
Ueda, Y.,
Shibata, R.,
Uno, S..
英文:
Yoshida, A.,
Namiki, M.,
Otani, C.,
Kawai, N.,
Murakami, T.,
Ueda, Y.,
Shibata, R.,
Uno, S..
言語
English
掲載誌/書名
和文:
英文:
Astronomische Nachrichten
巻, 号, ページ
Vol. 320
pp. 263
出版年月
1999年
出版者
和文:
英文:
会議名称
和文:
英文:
開催地
和文:
英文:
アブストラクト
An ASCA observation of an X-ray afterglow of a gamma-ray burst on 28 August 1997 (GRB970828) revealed the evidence of matter near the GRB. The spectral data obtained with the observation display a large absorption column density and an emission line at ~ 5 keV. The latter is possibly a red-shifted Fe line. Hence one can derive z=0.33 from the X-ray data for this GRB of unknown distance. This is the first GRB with its red shift determined only by the X-ray observation. The absorption density is estimated to be N_H, src=(6.8 +4.2}_{ -3.1})*E{21 cm-2 if the absorbing material is at z=0.33. This is remarkably high and may imply the GRB embedded in a galaxy. The line showed a time variability with a time-scale of ~ 104 s, from which we found that the line was formed by the dense matter in the vicinity of the GRB due to the photoionization-recombination process or the ``reflection'' of an intense radiation.
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