Spectral Evolution of the GRB 030329 Afterglow: Detection of the Supernova Nebular Phase Emissions

George Kosugi, Yoshihiko Mizumoto, Nobuyuki Kawai, Atsumasa Yoshida, Koji S. Kawabata, Tomonori Totani, Masanori Iye, Kazuhiro Sekiguchi, Kentaro Aoki, Youichi Ohyama, Wako Aoki, Naoto Kobayashi, Yutaka Komiyama, Jun'ichi Noumaru, Ryusuke Ogasawara, Takanori Sakamoto, Yuji Shirasaki, Tadafumi Takata, Toru Tamagawa, Ken'ichi ToriiYuji Urata, Jun ichi Watanabe, Toru Yamada, Yulei Qiu

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


GRB 030329 is the first Gamma-ray burst event for which a connection with a supernova (SN 2003dh) has been confirmed spectroscopically in its early phase. We present optical spectroscopy of this object 40 and 85 days after the burst (35 and 73 rest-frame days, respectively) obtained with the Subaru 8.2-m telescope. After subtracting the host galaxy template spectrum, the second-epoch spectrum shows nebular-phase emission lines emerging from the dominated photospheric-phase spectrum. The transition from the photospheric phase to the nebular phase has just started, or was slowly progressing at the time of our second-epoch observations. Our spectral analysis of the nebular-phase emission lines suggests that the explosion of the progenitor of the GRB 030329 was aspherical, and that the axis of an asphericity is well aligned to both the GRB relativistic jet and our line of sight. Although the decay index and the color evolution in the rest frame during our two epochs are very consistent with those of the Type le supernovae SN 1998bw and SN 1997ef, the nebular-phase lines emerged slightly earlier than in the case of these supernovae. These results infer that the most important factor that distinguishes SNe with GRB from SNe without GRB is the scale of the jet activity, or a viewing-angle effect, or both of them.

Original languageEnglish
Pages (from-to)61-68
Number of pages8
JournalPublications of the Astronomical Society of Japan
Issue number1
Publication statusPublished - 2004
Externally publishedYes


  • Cosmology: early universe
  • Gamma rays: bursts
  • Gamma rays: individual (GRB 030329)
  • Gamma rays: observations
  • Stars: supernovae: individual (SN 2003dh)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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