arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2410.09415astro-ph.HE
收藏

Fermi/GBM观测到的具有延展辐射的短伽马射线暴中的热辐射

The thermal emission in short GRBs with extended emission observed by Fermi/GBM

Xue-Zhao Chang, Hou-Jun Lü, Xing Yang, Jia-Ming Chen, En-Wei Liang

AI总结:

本文系统分析了Fermi/GBM观测的36个含延展辐射的短暴,发现多数暴存在准热成分,四个亮暴中热与非热辐射共存,支持混合喷流模型,且主辐射与延展辐射光谱演化相关,可能同源。

摘要:

具有延展辐射(EE)的短伽马射线暴(SGRBs)由初始的主辐射(ME)和随后的长时延展辐射组成,其中主辐射表现为短而硬的尖峰。ME和EE是否起源于同一物理机制,以及喷流的组成成分,仍是未解之谜。本文对我们样本中的36个伽马射线暴(GRBs)进行了系统分析,这些暴被识别为Fermi/伽马射线暴监测仪(GBM)观测到的具有延展辐射的短暴类别。通过使用截断幂律或Band模型提取样本中ME和EE的时间积分谱,我们发现36个SGRBs中有20个的α值在ME或EE阶段超过了同步辐射的死亡线(例如-2/3),这表明在瞬时辐射中应存在准热成分。随后,我们提取了样本的时间分辨谱,但只有4个GRBs足够亮以提取时间分辨谱。我们发现这4个亮GRBs的瞬时辐射中同时存在热和非热辐射,这表明GRB中应存在混合喷流(例如物质和坡印廷通量外流)。此外,在这4个GRBs的ME和EE时间分辨谱中发现了强正相关关系(如$F_{\ m tot}-Γ$和$F_{\ m tot}-kT$)。这表明ME和EE的光谱演化似乎表现出相似的行为,可能源于相同的物理起源。

英文摘要:

Short gamma-ray bursts (SGRBs) with extended emission (EE) are composed of initial main emission (ME) with a short-hard spike, followed by a long-lasting EE. Whether the ME and EE originated from the same origin or not, as well as the jet composition, remains an open question. In this paper, we present a systematic analysis of 36 gamma ray bursts (GRBs) in our sample, which are identified as the category of SGRBs with EE as observed by Fermi/Gamma-ray Burst Monitor. By extracting time-integrated spectra of ME and EE with cutoff power-law or Band models for our sample, we find that 20 out of 36 SGRBs have $α$ values that exceed the death line (e.g., -2/3) of synchrotron emission within either ME or EE phases, and we suggest that the quasi-thermal component should exist in the prompt emission. Then, we extract the time-resolved spectra of our samples, but only four GRBs are bright enough to extract the time-resolved spectra. We find that both thermal and nonthermal emissions do exist in the prompt emission of those four bright GRBs, which suggests that a hybrid jet (e.g., matter and Poynting-flux outflow) in GRBs should exist. Moreover, strong positive correlations (e.g., $F_{\rm tot}-Γ$ and $F_{\rm tot}-kT$) in the time-resolved spectra of ME and EE for those four GRBs have been discovered. This indicates that the spectral evolution of both ME and EE seem to share similar behavior, possibly from the same physical origin.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑