Signature of Triaxially Precessing Magnetars in Gamma-Ray Burst X-Ray Afterglows
The X-ray afterglows of some gamma-ray bursts (GRBs) exhibit plateaus, which can be explained by the internal dissipation of a newborn millisecond magnetar wind. In the early phase of these newborn magnetars, the magnetic inclination angle undergoes periodic changes due to precession, leading to per...
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IOP Publishing
2024-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9005 |
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| author | Biao Zhang Shu-Qing Zhong Long Li Zi-Gao Dai |
| author_facet | Biao Zhang Shu-Qing Zhong Long Li Zi-Gao Dai |
| author_sort | Biao Zhang |
| collection | DOAJ |
| description | The X-ray afterglows of some gamma-ray bursts (GRBs) exhibit plateaus, which can be explained by the internal dissipation of a newborn millisecond magnetar wind. In the early phase of these newborn magnetars, the magnetic inclination angle undergoes periodic changes due to precession, leading to periodic modulation of the injection luminosity due to magnetic dipole radiation. This may result in quasiperiodic oscillations on the plateaus. In this paper, we identify four GRBs with regular flux variations on their X-ray afterglow plateaus from Swift/X-Ray Telescope data before 2023 November, three of which exhibit periodicity. Based on the likelihood of supporting a precessing magnetar as the central engine, we classify them into three categories: Gold (GRB 060202 and GRB 180620A), Silver (GRB 050730), and Bronze (GRB 210610A). We invoke a model of magnetic dipole radiation emitted by a triaxially freely precessing magnetar whose spindown is dominated by electromagnetic radiation, to fit the light curves. Our model successfully reproduces the light curves of these four GRBs, including the regular flux variations on the plateaus and their periodicity (if present). Our work provides further evidence for early precession in newborn millisecond magnetars in GRBs. |
| format | Article |
| id | doaj-art-8f2b4b2dddcc400ca07f7aed6cfb36bd |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-8f2b4b2dddcc400ca07f7aed6cfb36bd2025-08-20T02:38:22ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01977220610.3847/1538-4357/ad9005Signature of Triaxially Precessing Magnetars in Gamma-Ray Burst X-Ray AfterglowsBiao Zhang0https://orcid.org/0009-0002-0930-1830Shu-Qing Zhong1https://orcid.org/0000-0002-1766-6947Long Li2https://orcid.org/0000-0002-8391-5980Zi-Gao Dai3https://orcid.org/0000-0002-7835-8585Department of Astronomy, University of Science and Technology of China , Hefei 230026, People's Republic of China ; daizg@ustc.edu.cn; School of Astronomy and Space Science, University of Science and Technology of China , Hefei 230026, People's Republic of ChinaDepartment of Astronomy, University of Science and Technology of China , Hefei 230026, People's Republic of China ; daizg@ustc.edu.cn; School of Astronomy and Space Science, University of Science and Technology of China , Hefei 230026, People's Republic of China; School of Science, Guangxi University of Science and Technology , Liuzhou 545006, People's Republic of ChinaDepartment of Astronomy, University of Science and Technology of China , Hefei 230026, People's Republic of China ; daizg@ustc.edu.cn; School of Astronomy and Space Science, University of Science and Technology of China , Hefei 230026, People's Republic of ChinaDepartment of Astronomy, University of Science and Technology of China , Hefei 230026, People's Republic of China ; daizg@ustc.edu.cn; School of Astronomy and Space Science, University of Science and Technology of China , Hefei 230026, People's Republic of ChinaThe X-ray afterglows of some gamma-ray bursts (GRBs) exhibit plateaus, which can be explained by the internal dissipation of a newborn millisecond magnetar wind. In the early phase of these newborn magnetars, the magnetic inclination angle undergoes periodic changes due to precession, leading to periodic modulation of the injection luminosity due to magnetic dipole radiation. This may result in quasiperiodic oscillations on the plateaus. In this paper, we identify four GRBs with regular flux variations on their X-ray afterglow plateaus from Swift/X-Ray Telescope data before 2023 November, three of which exhibit periodicity. Based on the likelihood of supporting a precessing magnetar as the central engine, we classify them into three categories: Gold (GRB 060202 and GRB 180620A), Silver (GRB 050730), and Bronze (GRB 210610A). We invoke a model of magnetic dipole radiation emitted by a triaxially freely precessing magnetar whose spindown is dominated by electromagnetic radiation, to fit the light curves. Our model successfully reproduces the light curves of these four GRBs, including the regular flux variations on the plateaus and their periodicity (if present). Our work provides further evidence for early precession in newborn millisecond magnetars in GRBs.https://doi.org/10.3847/1538-4357/ad9005Gamma-ray burstsMagnetars |
| spellingShingle | Biao Zhang Shu-Qing Zhong Long Li Zi-Gao Dai Signature of Triaxially Precessing Magnetars in Gamma-Ray Burst X-Ray Afterglows The Astrophysical Journal Gamma-ray bursts Magnetars |
| title | Signature of Triaxially Precessing Magnetars in Gamma-Ray Burst X-Ray Afterglows |
| title_full | Signature of Triaxially Precessing Magnetars in Gamma-Ray Burst X-Ray Afterglows |
| title_fullStr | Signature of Triaxially Precessing Magnetars in Gamma-Ray Burst X-Ray Afterglows |
| title_full_unstemmed | Signature of Triaxially Precessing Magnetars in Gamma-Ray Burst X-Ray Afterglows |
| title_short | Signature of Triaxially Precessing Magnetars in Gamma-Ray Burst X-Ray Afterglows |
| title_sort | signature of triaxially precessing magnetars in gamma ray burst x ray afterglows |
| topic | Gamma-ray bursts Magnetars |
| url | https://doi.org/10.3847/1538-4357/ad9005 |
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