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| Main Authors: | , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2503.15805 |
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| _version_ | 1866909661232365568 |
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| author | Du, Guowang Cheng, Yehao Yang, Yuan-Pei Yang, Jun Zhang, Jinghua Zhu, Dan Pan, Yu Fang, Yuan Zou, Xingzhu Kumar, Brajesh Guo, Helong Zhu, Xufeng Zhang, Yangwei Kong, Fanchuan Shang, Chenxi Chen, Xinlei Liu, Xiangkun Liu, Xiaowei |
| author_facet | Du, Guowang Cheng, Yehao Yang, Yuan-Pei Yang, Jun Zhang, Jinghua Zhu, Dan Pan, Yu Fang, Yuan Zou, Xingzhu Kumar, Brajesh Guo, Helong Zhu, Xufeng Zhang, Yangwei Kong, Fanchuan Shang, Chenxi Chen, Xinlei Liu, Xiangkun Liu, Xiaowei |
| contents | The interaction between the relativistic jet and the circumburst medium produces a multiwavelength afterglow of a gamma-ray burst (GRBs). In this work, we present multiwavelength properties of GRB~250101A based on the observations of Swift, Fermi and Mephisto. The spectral analysis of Swift/BAT and Fermi/GBM reveals a soft prompt spectrum with a low-energy photon index of $-1.18$ and a peak energy of 33 keV, and the isotropic energy is $1.4\times10^{52}~{\rm erg}$. The prompt emission of GRB 250101A aligns with Type II GRBs in the Amati relation. Meanwhile, our analysis indicates that GRB 250101A is an X-ray-rich or X-ray-dominated GRB, with intrinsic properties suggesting that it is relatively softer than most classical GRBs. Optical observation with Mephisto, beginning 197 s post-trigger, shows a single power-law decay in $uvgriz$ bands, with $F_{ν,\mathrm{obs}} \propto t^{-0.76} ν^{-1.21}$. The observed spectral index significantly exceeds theoretical predictions under standard afterglow models, suggesting a color excess of $\sim0.216$ mag. However, combining X-ray and optical afterglow, we find that GRB 250101A is more likely a ``normal burst'' rather than an ``optical-dark burst'', and the dust extinction effect plays an important role in the optical blue bands. Furthermore, there is a structural change at $T_0+2924$ s in the optical light curve, indicating a density drop of $\sim50$ \% in the interstellar medium at a distance of $\sim0.13~{\rm pc}$. Our analysis shows that this GRB clearly shows some unique characteristics in its observed X-ray rich prompt emission as well as the circumburst environment, implying a special progenitor. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_15805 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Multiwavelength Analysis of GRB 250101A: From Gamma-ray Prompt Emission to Optical Afterglow Du, Guowang Cheng, Yehao Yang, Yuan-Pei Yang, Jun Zhang, Jinghua Zhu, Dan Pan, Yu Fang, Yuan Zou, Xingzhu Kumar, Brajesh Guo, Helong Zhu, Xufeng Zhang, Yangwei Kong, Fanchuan Shang, Chenxi Chen, Xinlei Liu, Xiangkun Liu, Xiaowei High Energy Astrophysical Phenomena The interaction between the relativistic jet and the circumburst medium produces a multiwavelength afterglow of a gamma-ray burst (GRBs). In this work, we present multiwavelength properties of GRB~250101A based on the observations of Swift, Fermi and Mephisto. The spectral analysis of Swift/BAT and Fermi/GBM reveals a soft prompt spectrum with a low-energy photon index of $-1.18$ and a peak energy of 33 keV, and the isotropic energy is $1.4\times10^{52}~{\rm erg}$. The prompt emission of GRB 250101A aligns with Type II GRBs in the Amati relation. Meanwhile, our analysis indicates that GRB 250101A is an X-ray-rich or X-ray-dominated GRB, with intrinsic properties suggesting that it is relatively softer than most classical GRBs. Optical observation with Mephisto, beginning 197 s post-trigger, shows a single power-law decay in $uvgriz$ bands, with $F_{ν,\mathrm{obs}} \propto t^{-0.76} ν^{-1.21}$. The observed spectral index significantly exceeds theoretical predictions under standard afterglow models, suggesting a color excess of $\sim0.216$ mag. However, combining X-ray and optical afterglow, we find that GRB 250101A is more likely a ``normal burst'' rather than an ``optical-dark burst'', and the dust extinction effect plays an important role in the optical blue bands. Furthermore, there is a structural change at $T_0+2924$ s in the optical light curve, indicating a density drop of $\sim50$ \% in the interstellar medium at a distance of $\sim0.13~{\rm pc}$. Our analysis shows that this GRB clearly shows some unique characteristics in its observed X-ray rich prompt emission as well as the circumburst environment, implying a special progenitor. |
| title | Multiwavelength Analysis of GRB 250101A: From Gamma-ray Prompt Emission to Optical Afterglow |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2503.15805 |