Polarization Evolution of Gamma-Ray Burst Prompt Emission with Bulk Acceleration
During the prompt phase, Poynting-flux-dominated jets undergo acceleration accompanied by magnetic dissipation. By using an outward-propagating thin-shell model, where bulk Lorentz factors Γ increase with radius and the magnetic field strength decay is related to the acceleration and the energy conv...
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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/add0ac |
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| author | Qian Zhong Hong-Bang Liu Kangfa Cheng Zu-Ke Feng Jiang-Chuan Tuo Qian-Nan Mai Jirong Mao En-Wei Liang |
| author_facet | Qian Zhong Hong-Bang Liu Kangfa Cheng Zu-Ke Feng Jiang-Chuan Tuo Qian-Nan Mai Jirong Mao En-Wei Liang |
| author_sort | Qian Zhong |
| collection | DOAJ |
| description | During the prompt phase, Poynting-flux-dominated jets undergo acceleration accompanied by magnetic dissipation. By using an outward-propagating thin-shell model, where bulk Lorentz factors Γ increase with radius and the magnetic field strength decay is related to the acceleration and the energy conversion rate, this process can be investigated through time-resolved polarization analysis. Faster acceleration produces a greater flux, steeper light-curve growth followed by a sharper decline, and polarization degree decreases sharply. With a fixed acceleration index, lower energy conversion rates are associated with lower flux, shallower rises and declines in light curves, lower polarization degree, smoother decline for on-beam ( q = θ _v / θ _j < 1) emission, and sharper decline for off-beam ( q > 1) emission in polarization curves. Both jet acceleration and magnetic dissipation enhance the likelihood of polarization angle flips in observations with small viewing angles, while also leading to higher polarization degrees after the flip in observations with larger viewing angles. The joint analysis of light curves and polarization provides valuable insights into gamma-ray burst motion and energy conversion processes. Rapid decline in the light curve indicates fast acceleration and high energy conversion rates, while gradual light-curve decline coupled with polarization angle flips (for small viewing angles) or the higher polarization degree after flipping (for large viewing angles) suggests acceleration accompanied by magnetic dissipation. Otherwise, the jet is coasting or slowly accelerating at this time. |
| format | Article |
| id | doaj-art-3cc744bf686c4a20acf5958e8032c4dc |
| 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-3cc744bf686c4a20acf5958e8032c4dc2025-08-20T02:32:07ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198613210.3847/1538-4357/add0acPolarization Evolution of Gamma-Ray Burst Prompt Emission with Bulk AccelerationQian Zhong0https://orcid.org/0009-0003-9058-1768Hong-Bang Liu1https://orcid.org/0000-0003-1695-3263Kangfa Cheng2https://orcid.org/0009-0004-3324-8421Zu-Ke Feng3https://orcid.org/0009-0001-4885-0747Jiang-Chuan Tuo4https://orcid.org/0009-0002-3780-892XQian-Nan Mai5Jirong Mao6https://orcid.org/0000-0002-7077-7195En-Wei Liang7https://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 ; liuhb@gxu.edu.cnGuangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University , Nanning 530004, People’s Republic of China ; liuhb@gxu.edu.cnSchool of Mathematics and Physics, Guangxi Minzu University , Nanning 530006, People’s Republic of ChinaGuangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University , Nanning 530004, People’s Republic of China ; liuhb@gxu.edu.cnGuangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University , Nanning 530004, People’s Republic of China ; liuhb@gxu.edu.cnGuangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University , Nanning 530004, People’s Republic of China ; liuhb@gxu.edu.cnYunnan Observatories, Chinese Academy of Sciences , Kunming 650011, Yunnan Province, People’s Republic of China; Center for Astronomical Mega-Science, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of China; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences , Kunming 650011, People’s Republic of ChinaGuangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University , Nanning 530004, People’s Republic of China ; liuhb@gxu.edu.cnDuring the prompt phase, Poynting-flux-dominated jets undergo acceleration accompanied by magnetic dissipation. By using an outward-propagating thin-shell model, where bulk Lorentz factors Γ increase with radius and the magnetic field strength decay is related to the acceleration and the energy conversion rate, this process can be investigated through time-resolved polarization analysis. Faster acceleration produces a greater flux, steeper light-curve growth followed by a sharper decline, and polarization degree decreases sharply. With a fixed acceleration index, lower energy conversion rates are associated with lower flux, shallower rises and declines in light curves, lower polarization degree, smoother decline for on-beam ( q = θ _v / θ _j < 1) emission, and sharper decline for off-beam ( q > 1) emission in polarization curves. Both jet acceleration and magnetic dissipation enhance the likelihood of polarization angle flips in observations with small viewing angles, while also leading to higher polarization degrees after the flip in observations with larger viewing angles. The joint analysis of light curves and polarization provides valuable insights into gamma-ray burst motion and energy conversion processes. Rapid decline in the light curve indicates fast acceleration and high energy conversion rates, while gradual light-curve decline coupled with polarization angle flips (for small viewing angles) or the higher polarization degree after flipping (for large viewing angles) suggests acceleration accompanied by magnetic dissipation. Otherwise, the jet is coasting or slowly accelerating at this time.https://doi.org/10.3847/1538-4357/add0acGamma-ray burstsMagnetic fields |
| spellingShingle | Qian Zhong Hong-Bang Liu Kangfa Cheng Zu-Ke Feng Jiang-Chuan Tuo Qian-Nan Mai Jirong Mao En-Wei Liang Polarization Evolution of Gamma-Ray Burst Prompt Emission with Bulk Acceleration The Astrophysical Journal Gamma-ray bursts Magnetic fields |
| title | Polarization Evolution of Gamma-Ray Burst Prompt Emission with Bulk Acceleration |
| title_full | Polarization Evolution of Gamma-Ray Burst Prompt Emission with Bulk Acceleration |
| title_fullStr | Polarization Evolution of Gamma-Ray Burst Prompt Emission with Bulk Acceleration |
| title_full_unstemmed | Polarization Evolution of Gamma-Ray Burst Prompt Emission with Bulk Acceleration |
| title_short | Polarization Evolution of Gamma-Ray Burst Prompt Emission with Bulk Acceleration |
| title_sort | polarization evolution of gamma ray burst prompt emission with bulk acceleration |
| topic | Gamma-ray bursts Magnetic fields |
| url | https://doi.org/10.3847/1538-4357/add0ac |
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