Time-Resolved Spectral Variability of the Prompt Emission from GRB 070125 Observed with Suzaku/WAM

Kaori Onda, Makoto S. Tashiro, Yujin E. Nakagawa, Kazutaka Yamaoka, Yukikatsu Terada, Masanori Ohno, Satoshi Sugita, Takanori Sakamoto, Kenji Toma, Poshak Gandhi, Natsuki Kodak, Wataru Iwakiri, Yuji Urata, Makoto Yamauchi, Yasushi Fukazawa

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6 Citations (Scopus)


Time-resolved spectral analyses of GRB 070125 with significant photon detections over the MeV regime using Suzaku/WAM data are reported. The prompt emission interval was divided into 10 time regions, and their spectra were reproduced by a Band function or a cutoff power-law model. The spectra show a complex evolution; a soft-hard-soft trend is seen, rather than a typical hard-to-soft monotonic variation. In addition, a flat spectral slope in the low-energy band exceeding the slope expected from a simple synchrotron emission model is suggested in one of the time regions. These results imply that the internal shocks in the relativistic jet of GRB 070125 have different physical conditions. There is a possible excess at ∼ 2.2 MeV in the spectrum of 33 seconds after the trigger at a significant level of ≈ 98.5%, where the continuum spectrum is not reproduced by the Band function. These properties are only shown during the short prompt time interval of the prompt emission, and emphasize the utility of the Suzaku/WAM for the study of gamma-ray bursts.

Original languageEnglish
Pages (from-to)547-556
Number of pages10
JournalPublication of the Astronomical Society of Japan
Issue number3
Publication statusPublished - 2010


  • Gamma rays: burst
  • Gamma rays: observations
  • X-rays: individual (GRB 070125)


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