Swift and Suzaku observations of the X-ray afterglow from the GRB 060105

Makoto S. Tashiro, Keiichi Abe, Lorella Angelini, Scott Barthelmy, Neil Gehrels, Nobuyuki Ishikawa, Louis J. Kaluzienski, Nobuyuki Kawai, Richard L. Kelley, Kenzo Kinugasa, Hironobu Kodaira, Takayoshi Kohmura, Kaori Kubota, Yoshitomo Maeda, Shouta Maeno, Hiroshi Murakami, Toshio Murakami, Yujin E. Nakagawa, Kazuhiro Nakazawa, John NousekShin'ya Okuno, Kaori Onda, James N. Reeves, George Ricker, Goro Sato, Eri Sonoda, Motoko Suzuki, Tadayuki Takahashi, Toni Tamagawa, Ken'ichi Torii, Yoshihiro Ueda, Yuji Urata, Kazutaka Yamaoka, Makoto Yamauchi, Daisuke Yonetoku, Atsumasa Yoshida, Satoru Yoshinari

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Results are presented of early X-ray afterglow observations of GRB 060105 by Swift and Suzaku. The bright, long gamma-ray burst GRB 060105 triggered the Swift Burst Alert Telescope at 06:49:28 on 2006 January 5 (T0). The Suzaku team commenced a pre-planned target of opportunity observation at 19 ks (5.3 hr) after the Swift trigger. The X-ray flux faded during observations from 6.8 × 10-9 erg s-1 cm-2 (at T0 + 87 s with the Swift/XRT) to 1.5 × 10-13 erg s-1 cm-2 [at T0 + 94-101 ks with the Suzaku X-ray Imaging Spectrometer (XIS)] in the 2-10 keV energy band. Following prompt emission and successive very steep decay, a shallow decay was observed from T0 + 187 s to T0 + 1287 s. After an observation gap during T0 + (1.5-3) ks, an extremely early steep decay was observed in T0 + (4-30) ks. The lightcurve flattened again at T0 + 30ks, and another steep decay followed from T0 + 50ks to the end of observations. Both steep decays exhibited decay indices of 2.3-2.4. This very early break, if it is a jet break, is the earliest case among X-ray afterglow observations, suggesting a very narrow jet whose opening angle is well below 1°. The unique Suzaku/XIS data allow us to set very tight upper limits on line emission or absorption in this GRB. For the reported pseudo-redshift of z = 4.0 ± 1.3 the upper limit on the iron line equivalent width is 50 eV.

Original languageEnglish
JournalPublications of the Astronomical Society of Japan
Volume59
Issue number1 SPEC. ISS.
Publication statusPublished - 2007

Keywords

  • Gamma rays: burst
  • Radiation mechanisms: non-thermal
  • Relativistic jet
  • X-rays: individual (GRB 060105)
  • X-rays: stars acceleration of particles

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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