Magnetic Structures in Gamma-Ray Burst Jets Probed by Gamma-Ray Polarization

Autor:	Yonetoku, Daisuke, Murakami, Toshio, Gunji, Shuichi, Mihara, Tatehiro, Toma, Kenji, Morihara, Yoshiyuki, Takahashi, Takuya, Wakashima, Yudai, Yonemochi, Hajime, Sakashita, Tomonori, Toukairin, Noriyuki, Fujimoto, Hirofumi, Kodama, Yoshiki
Rok vydání:	2012
Předmět:	Astrophysics - High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology High Energy Physics - Phenomenology
Druh dokumentu:	Working Paper
DOI:	10.1088/2041-8205/758/1/L1
Popis:	We report polarization measurements in two prompt emissions of gamma-ray bursts, GRB 110301A and GRB 110721A, observed with the Gamma-ray burst polarimeter (GAP) aboard IKAROS solar sail mission. We detected linear polarization signals from each burst with polarization degree of $\Pi = 70 \pm 22$% with statistical significance of $3.7 \sigma$ for GRB 110301A, and $\Pi = 84^{+16}_{-28}$% with $3.3 \sigma$ confidence level for GRB 110721A. We did not detect any significant change of polarization angle. These two events had shorter durations and dimmer brightness compared with GRB 100826A, which showed a significant change of polarization angle, as reported in Yonetoku et al. (2011). Synchrotron emission model can be consistent with all the data of the three GRBs, while photospheric quasi-thermal emission model is not favorable. We suggest that magnetic field structures in the emission region are globally-ordered fields advected from the central engine. Comment: Accepted for publication to ApJL (7 pages, 3 figures)
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/1208.5287 Zobrazit plný text záznamu View this record from Arxiv