Suzaku and Swift observations for X-ray afterglows; Investigation into the electron acceleration in the internal/external shocks

Daisuke Yonetoku, Sachiko Tanabe, Toshio Murakami, N. Emura, Y. Aoyama, T. Kidamura, H. Kodaira, Y. Kodama, R. Kozaka, T. Nashimoto, S. Okuno, S. Yokota, S. Yoshinari, K. Abe, K. Onda, M. S. Tashiro, Y. Urata, Y. E. Nakagawa, S. Sugita, K. YamaokaA. Yoshida, T. Ishimura, N. Kawai, T. Shimokawabe, K. Kinugasa, T. Kohmura, K. Kubota, K. Sugiyasu, Y. Ueda, K. Masui, K. Nakazawa, T. Takahashi, S. Maeno, E. Sonoda, M. Yamauchi, M. Kuwahara, T. Tamagawa, D. Matsuura, M. Suzuki, N. Gehrels, J. Nousek

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We have performed ToO observations for three bright GRBs with the Japanese X-ray satellite Suzaku. Suzaku strongly supports the follow-up observations by Swift, especially in the late time afterglow phase, with its capabilities of larger effective area and wider energy band compared with Swift/XRT. In this presentation, mainly focusing on the X-ray afterglow of GRB 060904A, we introduce these ToO observation results. In GRB 060904A, we found rapid spectral softening with the photon indices from 1.5 to 5.3 during the steep decay (prompt tail) phase in the BAT and XRT data. This ultra soft spectra suddenly disappeared at the transition time from the prompt tail phase to the shallow decay one. After that, typical afterglow spectra with the photon indices of 2.0 are continuously and preciously monitored by both XRT and Suzaku/XIS up to 1 day since the burst trigger time. To explain this ultra soft spectra, we introduce a spectral cutoff model instead of power-law, and investigate the possibility of the maximum energy of electron distribution. We could successfully trace the temporal history of cutoff energy and it shows the time dependence of ∝t-3∼t-4 while the following afterglow spectra are quite stable. This fact indicates that the emitting material of prompt tail is due to completely different dynamics from the shallow decay component. Therefore we conclude the emission sites of two distinct phenomena obviously differ from each other.

Original languageEnglish (US)
Title of host publicationGamma-Ray Bursts 2007 - Proceedings of the Santa Fe Conference
Number of pages4
StatePublished - 2008
EventSanta Fe Conference on Gamma-Ray Bursts 2007, GRB 2007 - Santa Fe, NM, United States
Duration: Nov 5 2007Nov 9 2007

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


OtherSanta Fe Conference on Gamma-Ray Bursts 2007, GRB 2007
Country/TerritoryUnited States
CitySanta Fe, NM

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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