Study of emission mechanism of GRBs probed by the gamma-ray polarization with IKAROS-GAP

Daisuke Yonetoku; Toshio Murakami; Tomonori Sakashita; Yoshiyuki Morihara; Shuichi Gunji; Tatehiro Mihara; Kenji Toma

doi:10.1017/S174392131201366X

Study of emission mechanism of GRBs probed by the gamma-ray polarization with IKAROS-GAP

Daisuke Yonetoku, Toshio Murakami, Tomonori Sakashita, Yoshiyuki Morihara, Shuichi Gunji, Tatehiro Mihara, Kenji Toma

Creative Interdisciplinary Research Division

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Abstract

We report a polarization measurement in prompt γ-ray emission of GRB 100826A with the Gamma-Ray Burst Polarimeter (GAP) aboard the small solar power sail demonstrator IKAROS. We detected a firm change of polarization angle (PA) during the prompt emission with 99.9% (3.5 σ) confidence level, and an average polarization degree (II) of 27 ± 11% with 99.4% (2.9 σ) confidence level. Here the quoted errors are given at 1 σ confidence level for two parameters of interest. Non-axisymmetric (e.g., patchy) structures of the magnetic fields and/or brightness inside the relativistic jet are therefore required within the observable angular scale of ∼ σ ^-1. Our observation strongly indicates that the polarization measurement is a powerful tool to constrain the GRB production mechanism, and more theoretical works are needed to discuss the data in more details.

Original language	English
Title of host publication	Death of Massive Stars
Subtitle of host publication	Supernovae and Gamma-Ray Bursts
Editors	Peter W. A. San Antonio, Nobuyuki Kawai, Elena Pian
Pages	425-426
Number of pages	2
Edition	S279
DOIs	https://doi.org/10.1017/S174392131201366X
Publication status	Published - 2011 Apr

Publication series

Name	Proceedings of the International Astronomical Union
Number	S279
Volume	7
ISSN (Print)	1743-9213
ISSN (Electronic)	1743-9221

Keywords

Gamma-Ray Bursts
emission mechanism
polarization

ASJC Scopus subject areas

Medicine (miscellaneous)
Astronomy and Astrophysics
Nutrition and Dietetics
Public Health, Environmental and Occupational Health
Space and Planetary Science

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10.1017/S174392131201366X

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Yonetoku, D., Murakami, T., Sakashita, T., Morihara, Y., Gunji, S., Mihara, T., & Toma, K. (2011). Study of emission mechanism of GRBs probed by the gamma-ray polarization with IKAROS-GAP. In P. W. A. San Antonio, N. Kawai, & E. Pian (Eds.), Death of Massive Stars: Supernovae and Gamma-Ray Bursts (S279 ed., pp. 425-426). (Proceedings of the International Astronomical Union; Vol. 7, No. S279). https://doi.org/10.1017/S174392131201366X

Study of emission mechanism of GRBs probed by the gamma-ray polarization with IKAROS-GAP. / Yonetoku, Daisuke; Murakami, Toshio; Sakashita, Tomonori; Morihara, Yoshiyuki; Gunji, Shuichi; Mihara, Tatehiro; Toma, Kenji.

Death of Massive Stars: Supernovae and Gamma-Ray Bursts. ed. / Peter W. A. San Antonio; Nobuyuki Kawai; Elena Pian. S279. ed. 2011. p. 425-426 (Proceedings of the International Astronomical Union; Vol. 7, No. S279).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Yonetoku, D, Murakami, T, Sakashita, T, Morihara, Y, Gunji, S, Mihara, T & Toma, K 2011, Study of emission mechanism of GRBs probed by the gamma-ray polarization with IKAROS-GAP. in PWA San Antonio, N Kawai & E Pian (eds), Death of Massive Stars: Supernovae and Gamma-Ray Bursts. S279 edn, Proceedings of the International Astronomical Union, no. S279, vol. 7, pp. 425-426. https://doi.org/10.1017/S174392131201366X

Yonetoku D, Murakami T, Sakashita T, Morihara Y, Gunji S, Mihara T et al. Study of emission mechanism of GRBs probed by the gamma-ray polarization with IKAROS-GAP. In San Antonio PWA, Kawai N, Pian E, editors, Death of Massive Stars: Supernovae and Gamma-Ray Bursts. S279 ed. 2011. p. 425-426. (Proceedings of the International Astronomical Union; S279). https://doi.org/10.1017/S174392131201366X

Yonetoku, Daisuke ; Murakami, Toshio ; Sakashita, Tomonori ; Morihara, Yoshiyuki ; Gunji, Shuichi ; Mihara, Tatehiro ; Toma, Kenji. / Study of emission mechanism of GRBs probed by the gamma-ray polarization with IKAROS-GAP. Death of Massive Stars: Supernovae and Gamma-Ray Bursts. editor / Peter W. A. San Antonio ; Nobuyuki Kawai ; Elena Pian. S279. ed. 2011. pp. 425-426 (Proceedings of the International Astronomical Union; S279).

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abstract = "We report a polarization measurement in prompt γ-ray emission of GRB 100826A with the Gamma-Ray Burst Polarimeter (GAP) aboard the small solar power sail demonstrator IKAROS. We detected a firm change of polarization angle (PA) during the prompt emission with 99.9% (3.5 σ) confidence level, and an average polarization degree (II) of 27 ± 11% with 99.4% (2.9 σ) confidence level. Here the quoted errors are given at 1 σ confidence level for two parameters of interest. Non-axisymmetric (e.g., patchy) structures of the magnetic fields and/or brightness inside the relativistic jet are therefore required within the observable angular scale of ∼ σ -1. Our observation strongly indicates that the polarization measurement is a powerful tool to constrain the GRB production mechanism, and more theoretical works are needed to discuss the data in more details.",

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AU - Yonetoku, Daisuke

AU - Murakami, Toshio

AU - Sakashita, Tomonori

AU - Morihara, Yoshiyuki

AU - Gunji, Shuichi

AU - Mihara, Tatehiro

AU - Toma, Kenji

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N2 - We report a polarization measurement in prompt γ-ray emission of GRB 100826A with the Gamma-Ray Burst Polarimeter (GAP) aboard the small solar power sail demonstrator IKAROS. We detected a firm change of polarization angle (PA) during the prompt emission with 99.9% (3.5 σ) confidence level, and an average polarization degree (II) of 27 ± 11% with 99.4% (2.9 σ) confidence level. Here the quoted errors are given at 1 σ confidence level for two parameters of interest. Non-axisymmetric (e.g., patchy) structures of the magnetic fields and/or brightness inside the relativistic jet are therefore required within the observable angular scale of ∼ σ -1. Our observation strongly indicates that the polarization measurement is a powerful tool to constrain the GRB production mechanism, and more theoretical works are needed to discuss the data in more details.

AB - We report a polarization measurement in prompt γ-ray emission of GRB 100826A with the Gamma-Ray Burst Polarimeter (GAP) aboard the small solar power sail demonstrator IKAROS. We detected a firm change of polarization angle (PA) during the prompt emission with 99.9% (3.5 σ) confidence level, and an average polarization degree (II) of 27 ± 11% with 99.4% (2.9 σ) confidence level. Here the quoted errors are given at 1 σ confidence level for two parameters of interest. Non-axisymmetric (e.g., patchy) structures of the magnetic fields and/or brightness inside the relativistic jet are therefore required within the observable angular scale of ∼ σ -1. Our observation strongly indicates that the polarization measurement is a powerful tool to constrain the GRB production mechanism, and more theoretical works are needed to discuss the data in more details.

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