等待时机：来自高纬度辐射和喷流膨胀的延展发射伽马射线暴
Waiting in the wings: extended emission GRBs from high latitude emission and jet expansion
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中文总结 AI 辅助
本文提出解析薄壳结构化喷流模型，通过高洛伦兹因子窄喷流与低洛伦兹因子宽喷流结合，解释致密天体并合延展发射GRB的长时间尺度，并成功匹配Swift观测光变曲线。
中文摘要 AI 辅助
致密天体并合产生的延展发射（EE）伽马射线暴（GRBs）的驱动过程是一个备受争议的问题，因为观测到的瞬时发射时标为10至100秒，远超双中子星（BNS）并合后预期的吸积时标。在此，我们提出一个解析薄壳结构化喷流模型，旨在缓解这一矛盾。我们表明，变化的喷流结构——早期发射由高洛伦兹因子的窄结构化喷流产生，后期发射来自更宽、更低洛伦兹因子的类顶帽喷流——能够成功再现EE GRB现象。所有发射壳层均由一个0.1太阳质量的吸积环面提供能量，并在并合后2秒的时间窗口内发射。空间分辨的光深检查确认我们的发射区域保持光学薄，部分原因在于与EE相关的谱软性。我们展示了模型的光变曲线，并与Swift探测到的代表性EE暴GRBs 211211A、211227A和060614进行比较。虽然我们的光变曲线与数据匹配良好，但我们的光谱演化速度不足以与GRB 211211A中观测到的良好测量的谱演化相比。我们讨论了一个模型更新，将壳层内固有的谱演化作为未来工作。我们还展示了模型的参数探索，并确定了一个参数范围，在该范围内可以产生标准的短GRB-like光变曲线，展示了模型产生带或不带EE的短暴的能力。
英文摘要
The process powering extended emission (EE) Gamma Ray-Bursts (GRBs) from compact object mergers is a debated problem due to their observed prompt emission timescales of 10 to 100s, far in excess of the expected accretion timescales following a binary neutron star (BNS) merger. Here, we present an analytical thin shell structured jet model designed to alleviate this tension. We show that a changing jet structure in which early emission is produced by a high Lorentz factor narrow, structured jet and later emission comes from a wider, lower Lorentz factor tophat-like jet can successfully reproduce the EE GRB phenomenology. All emitting shells are powered by a $0.1$ $M_{\odot}$ accretion torus and launched within a time window of 2s after merger. Spatially-resolved opacity checks confirm that our emission sites remain optically thin, in part due to the spectral softness associated with EE. We present light curves from our model compared to representative EE bursts detected by Swift: GRBs 211211A, 211227A and 060614. While our light curves provide good matches to the data, our spectra do not evolve fast enough when compared to the well-measured spectral evolution observed in GRB 211211A. We discuss an update to the model incorporating inherent spectral evolution in the shells as future work. We also show a parameter exploration of the model and identify a parameter range within which standard short GRB-like light curves could be produced, showcasing the ability of the model to produce short bursts with and without EE.
发表机构
- School of Physics and Astronomy, University of Birmingham（伯明翰大学物理与天文学院）
- Institute for Gravitational Wave Astronomy, University of Birmingham（伯明翰大学引力波天文学研究所）
- Department of Physics, University of Bath（巴斯大学物理系）
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