On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009A
The temporal evolution of the TeV emission of GRB 221009A displays a smooth transition from an initial rapid rise to a slower rise and eventually a decay phase. The smooth light curve suggests an afterglow origin of the TeV emission. The temporal overlap between the prompt keV–MeV emission and the e...
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| Language: | English |
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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/adc442 |
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| author | Cui-Yuan Dai Jian-He Zheng Xiao-Hong Zhao Ruo-Yu Liu Xiang-Yu Wang |
| author_facet | Cui-Yuan Dai Jian-He Zheng Xiao-Hong Zhao Ruo-Yu Liu Xiang-Yu Wang |
| author_sort | Cui-Yuan Dai |
| collection | DOAJ |
| description | The temporal evolution of the TeV emission of GRB 221009A displays a smooth transition from an initial rapid rise to a slower rise and eventually a decay phase. The smooth light curve suggests an afterglow origin of the TeV emission. The temporal overlap between the prompt keV–MeV emission and the early TeV afterglow indicates that external inverse Compton (EIC) scattering between the prompt keV–MeV photons and the afterglow electrons is inevitable. Since the energy density of the prompt emission is much higher than that of the afterglow during the early phase, the EIC process dominates the cooling of afterglow electrons. The EIC scattering rate is influenced by the anisotropy of the seed photon field, which depends on the radius of the internal dissipation ( R _dis ), where the prompt emission is produced, and that of the external shock ( R _ext ), where the afterglow emission is produced. We investigate the EIC process for different values of R _dis / R _ext and find that the EIC scattering rate can differ by a factor of ∼2 accordingly. For GRB 221009A, the EIC emission dominates during the early rising phase of the TeV afterglow. It then transitions to a phase dominated by the synchrotron self-Compton emission as the intensity of the prompt emission decreases. Additionally, we investigate the effect of γγ absorption in the TeV afterglow by prompt MeV photons and find it insufficient to explain the early rapid rise in the TeV afterglow. |
| format | Article |
| id | doaj-art-af3fbcefe1e34e88b73baea0ae85f2d3 |
| institution | DOAJ |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| spelling | doaj-art-af3fbcefe1e34e88b73baea0ae85f2d32025-08-20T02:56:10ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01984219210.3847/1538-4357/adc442On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009ACui-Yuan Dai0https://orcid.org/0000-0002-0170-0741Jian-He Zheng1https://orcid.org/0000-0001-5751-633XXiao-Hong Zhao2https://orcid.org/0000-0003-3659-4800Ruo-Yu Liu3https://orcid.org/0000-0003-1576-0961Xiang-Yu Wang4https://orcid.org/0000-0002-5881-335XSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People’s Republic of China ; ryliu@nju.edu.cn, xywang@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210023, People’s Republic of ChinaSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People’s Republic of China ; ryliu@nju.edu.cn, xywang@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210023, People’s Republic of ChinaYunnan Observatories, Chinese Academy of Sciences Kunming , 650011, People’s Republic of China; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Science Kunming , 650011, People’s Republic of China; Center for Astronomical Mega-Science, Chinese Academy of Science , 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of ChinaSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People’s Republic of China ; ryliu@nju.edu.cn, xywang@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210023, People’s Republic of ChinaSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People’s Republic of China ; ryliu@nju.edu.cn, xywang@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210023, People’s Republic of ChinaThe temporal evolution of the TeV emission of GRB 221009A displays a smooth transition from an initial rapid rise to a slower rise and eventually a decay phase. The smooth light curve suggests an afterglow origin of the TeV emission. The temporal overlap between the prompt keV–MeV emission and the early TeV afterglow indicates that external inverse Compton (EIC) scattering between the prompt keV–MeV photons and the afterglow electrons is inevitable. Since the energy density of the prompt emission is much higher than that of the afterglow during the early phase, the EIC process dominates the cooling of afterglow electrons. The EIC scattering rate is influenced by the anisotropy of the seed photon field, which depends on the radius of the internal dissipation ( R _dis ), where the prompt emission is produced, and that of the external shock ( R _ext ), where the afterglow emission is produced. We investigate the EIC process for different values of R _dis / R _ext and find that the EIC scattering rate can differ by a factor of ∼2 accordingly. For GRB 221009A, the EIC emission dominates during the early rising phase of the TeV afterglow. It then transitions to a phase dominated by the synchrotron self-Compton emission as the intensity of the prompt emission decreases. Additionally, we investigate the effect of γγ absorption in the TeV afterglow by prompt MeV photons and find it insufficient to explain the early rapid rise in the TeV afterglow.https://doi.org/10.3847/1538-4357/adc442Gamma-ray burstsNon-thermal radiation sourcesRadiative processes |
| spellingShingle | Cui-Yuan Dai Jian-He Zheng Xiao-Hong Zhao Ruo-Yu Liu Xiang-Yu Wang On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009A The Astrophysical Journal Gamma-ray bursts Non-thermal radiation sources Radiative processes |
| title | On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009A |
| title_full | On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009A |
| title_fullStr | On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009A |
| title_full_unstemmed | On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009A |
| title_short | On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009A |
| title_sort | on the external inverse compton scattering off the prompt emission in grb 221009a |
| topic | Gamma-ray bursts Non-thermal radiation sources Radiative processes |
| url | https://doi.org/10.3847/1538-4357/adc442 |
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