HIGH-ENERGY NON-THERMAL and THERMAL EMISSION from GRB 141207A DETECTED by FERMI

Makoto Arimoto, Katsuaki Asano, Masanori Ohno, Péter Veres, Magnus Axelsson, Elisabetta Bissaldi, Yutaro Tachibana, Nobuyuki Kawai

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

A bright long gamma-ray burst GRB 141207A was observed by the Fermi Gamma-ray Space Telescope and detected by both instruments onboard. The observations show that the spectrum in the prompt phase is not well described by the canonical empirical Band function alone, and that an additional power-law component is needed. In the early phase of the prompt emission, a modified blackbody with a hard low-energy photon index (α = +0.2 to +0.4) is detected, which suggests a photospheric origin. In a finely time-resolved analysis, the spectra are also well fitted by the modified blackbody combined with a power-law function. We discuss the physical parameters of the photosphere such as the bulk Lorentz factor of the relativistic flow and the radius. We also discuss the physical origin of the extra power-law component observed during the prompt phase in the context of different models such as leptonic and hadronic scenarios in the internal shock regime and synchrotron emission in the external forward shock. In the afterglow phase, the temporal and spectral behaviors of the temporally extended high-energy emission and the fading X-ray emission detected by the X-Ray Telescope on-board Swift are consistent with synchrotron emission in a radiative external forward shock.

Original languageEnglish
Article number139
JournalAstrophysical Journal
Volume833
Issue number2
DOIs
Publication statusPublished - 2016 Dec 20

Keywords

  • acceleration of particles
  • gamma-ray burst: individual (GRB 141207A)
  • radiation mechanisms: thermal

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Arimoto, M., Asano, K., Ohno, M., Veres, P., Axelsson, M., Bissaldi, E., Tachibana, Y., & Kawai, N. (2016). HIGH-ENERGY NON-THERMAL and THERMAL EMISSION from GRB 141207A DETECTED by FERMI. Astrophysical Journal, 833(2), [139]. https://doi.org/10.3847/1538-4357/833/2/139