Identifying the poynting-flux-dominated outflow of Fermi GRBs with non-thermal spectrum and its energy-resolved light curve fitting
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arXiv
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| Autores principales: | , , , , |
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| Formato: | Preprint |
| Publicado: |
2026
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| _version_ | 1866908752970514432 |
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| author | Chang, Xue-Zhao Lü, HouJun Du, Zhao-Wei Yang, Xing Liang, En-Wei |
| author_facet | Chang, Xue-Zhao Lü, HouJun Du, Zhao-Wei Yang, Xing Liang, En-Wei |
| contents | The jet compositions of gamma-ray bursts (GRBs) are very important to understand the energy dissipation and radiation mechanisms, but it remains an open question in GRB physics. In this paper, we present a systematic analysis to search for 88 bright GRBs that include a total of 129 pulses observed by Fermi/GBM with redshift measured, and extract the spectra of each pulse with Band function (Band), cutoff power-law (CPL), blackbody (BB), non-dissipative photospheric (NDP), Band+BB, as well as CPL+BB. We find that 80 pulses, 35 pulses, and 14 pulses present purely non-thermal, hybrid, and thermal spectra, respectively. By focusing on those 80 pulses with purely non-thermal spectra, one can estimate the lower limits of magnetization factor ($σ$) via suppressing the pseudo-thermal component. It is found that 30 pulses in 21 GRBs are the lower limit of $σ>5$ at the photosphere by adopting $R_{0}=10^{10}$ cm. It suggests that at least the outflow of those GRB jets with high $σ$ is dominated by Poynting-flux. On the other hand, we also perform the light curve fitting with a fast-rise-exponential-decay (FRED) model for 15 bright GRBs with a high magnetization factor in our sample, and find that a correlation between pulse width ($w$) and energy of 13 GRBs really exists in their energy-resolved light curves. It is also a piece of independent evidence for those GRBs with a high value $σ$ to support the origin of the Poynting flux outflow. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_04468 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Identifying the poynting-flux-dominated outflow of Fermi GRBs with non-thermal spectrum and its energy-resolved light curve fitting Chang, Xue-Zhao Lü, HouJun Du, Zhao-Wei Yang, Xing Liang, En-Wei High Energy Astrophysical Phenomena The jet compositions of gamma-ray bursts (GRBs) are very important to understand the energy dissipation and radiation mechanisms, but it remains an open question in GRB physics. In this paper, we present a systematic analysis to search for 88 bright GRBs that include a total of 129 pulses observed by Fermi/GBM with redshift measured, and extract the spectra of each pulse with Band function (Band), cutoff power-law (CPL), blackbody (BB), non-dissipative photospheric (NDP), Band+BB, as well as CPL+BB. We find that 80 pulses, 35 pulses, and 14 pulses present purely non-thermal, hybrid, and thermal spectra, respectively. By focusing on those 80 pulses with purely non-thermal spectra, one can estimate the lower limits of magnetization factor ($σ$) via suppressing the pseudo-thermal component. It is found that 30 pulses in 21 GRBs are the lower limit of $σ>5$ at the photosphere by adopting $R_{0}=10^{10}$ cm. It suggests that at least the outflow of those GRB jets with high $σ$ is dominated by Poynting-flux. On the other hand, we also perform the light curve fitting with a fast-rise-exponential-decay (FRED) model for 15 bright GRBs with a high magnetization factor in our sample, and find that a correlation between pulse width ($w$) and energy of 13 GRBs really exists in their energy-resolved light curves. It is also a piece of independent evidence for those GRBs with a high value $σ$ to support the origin of the Poynting flux outflow. |
| title | Identifying the poynting-flux-dominated outflow of Fermi GRBs with non-thermal spectrum and its energy-resolved light curve fitting |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2601.04468 |