Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. II. Viewing Angle Effect on the Prompt Emission and Application to GRB 170817A
Multimessenger observations suggest that the gamma-ray burst on 2017 August 17 (GRB 170817A) resulted from off-axial observations of its structured jet, which consists of a narrow ultrarelativistic jet core surrounded by a wide mild-relativistic cocoon. In a serious paper, we explore the emission of...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/adb722 |
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| author | Zi-Qi Wang Xiao-Li Huang En-Wei Liang |
| author_facet | Zi-Qi Wang Xiao-Li Huang En-Wei Liang |
| author_sort | Zi-Qi Wang |
| collection | DOAJ |
| description | Multimessenger observations suggest that the gamma-ray burst on 2017 August 17 (GRB 170817A) resulted from off-axial observations of its structured jet, which consists of a narrow ultrarelativistic jet core surrounded by a wide mild-relativistic cocoon. In a serious paper, we explore the emission of shear-accelerated electrons in the mixed jet-cocoon region in a series of papers. This paper focuses on the viewing angle effect for a structured jet by considering the emission from the shear-accelerated electrons. It is found that the observed synchrotron (Syn) emission peaks at the infrared band and the Syn self-Compton emission peaks at the band of hundreds of keV. They are not sensitive to the viewing angle. In the off-axis observations scenario, the prompt emission spectrum is dominated by the emission of the shear-accelerated electrons. The prompt gamma-ray spectrum of GRB 170817A can be well explained with our model by setting the velocity of the inner edge of the cocoon region as 0.9 c , the magnetic field strength as 21 G, the injected initial electron Lorentz factor as 10 ^3 , and the viewing angle as 0.44 rad. We argue that the joint observations in the infrared/optical and X-ray bands are critical to verify our model. |
| format | Article |
| id | doaj-art-54ee5beb6b664cd88c480350cb96e03b |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-54ee5beb6b664cd88c480350cb96e03b2025-08-20T01:57:59ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01981219610.3847/1538-4357/adb722Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. II. Viewing Angle Effect on the Prompt Emission and Application to GRB 170817AZi-Qi Wang0https://orcid.org/0009-0001-8025-3205Xiao-Li Huang1https://orcid.org/0000-0002-9725-7114En-Wei Liang2https://orcid.org/0000-0002-7044-733XGuangxi Key Laboratory for Relativistic Astrophysics , School of Physical Science and Technology, Guangxi University, Nanning 530004, People’s Republic of China ; lew@gxu.edu.cnGuangxi Key Laboratory for Relativistic Astrophysics , School of Physical Science and Technology, Guangxi University, Nanning 530004, People’s Republic of China ; lew@gxu.edu.cn; School of Physics and Electronic Science , Guizhou Normal University, Guiyang 550025, People’s Republic of China ; xiaoli.huang@gznu.edu.cn,Guangxi Key Laboratory for Relativistic Astrophysics , School of Physical Science and Technology, Guangxi University, Nanning 530004, People’s Republic of China ; lew@gxu.edu.cnMultimessenger observations suggest that the gamma-ray burst on 2017 August 17 (GRB 170817A) resulted from off-axial observations of its structured jet, which consists of a narrow ultrarelativistic jet core surrounded by a wide mild-relativistic cocoon. In a serious paper, we explore the emission of shear-accelerated electrons in the mixed jet-cocoon region in a series of papers. This paper focuses on the viewing angle effect for a structured jet by considering the emission from the shear-accelerated electrons. It is found that the observed synchrotron (Syn) emission peaks at the infrared band and the Syn self-Compton emission peaks at the band of hundreds of keV. They are not sensitive to the viewing angle. In the off-axis observations scenario, the prompt emission spectrum is dominated by the emission of the shear-accelerated electrons. The prompt gamma-ray spectrum of GRB 170817A can be well explained with our model by setting the velocity of the inner edge of the cocoon region as 0.9 c , the magnetic field strength as 21 G, the injected initial electron Lorentz factor as 10 ^3 , and the viewing angle as 0.44 rad. We argue that the joint observations in the infrared/optical and X-ray bands are critical to verify our model.https://doi.org/10.3847/1538-4357/adb722Gamma-ray burstsNon-thermal radiation sources |
| spellingShingle | Zi-Qi Wang Xiao-Li Huang En-Wei Liang Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. II. Viewing Angle Effect on the Prompt Emission and Application to GRB 170817A The Astrophysical Journal Gamma-ray bursts Non-thermal radiation sources |
| title | Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. II. Viewing Angle Effect on the Prompt Emission and Application to GRB 170817A |
| title_full | Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. II. Viewing Angle Effect on the Prompt Emission and Application to GRB 170817A |
| title_fullStr | Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. II. Viewing Angle Effect on the Prompt Emission and Application to GRB 170817A |
| title_full_unstemmed | Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. II. Viewing Angle Effect on the Prompt Emission and Application to GRB 170817A |
| title_short | Shear Particle Acceleration in Structured Gamma-Ray Burst Jets. II. Viewing Angle Effect on the Prompt Emission and Application to GRB 170817A |
| title_sort | shear particle acceleration in structured gamma ray burst jets ii viewing angle effect on the prompt emission and application to grb 170817a |
| topic | Gamma-ray bursts Non-thermal radiation sources |
| url | https://doi.org/10.3847/1538-4357/adb722 |
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