External Inverse-Compton Emission from Low-luminosity Gamma-Ray Bursts: Application to GRB 190829A
External Inverse-Compton Emission from Low-luminosity Gamma-Ray Bursts: Application to GRB 190829A
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DOI：
10.3847/1538-4357/ac0cfc
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发表时间：
2020-12
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影响因子：
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通讯作者：
B. Zhang;K. Murase;P. Veres;P. M'esz'aros
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作者：
B. Zhang;K. Murase;P. Veres;P. M'esz'aros
TeV伽玛射线暴的探测为研究相对论冲击下粒子加速物理带来了新的机遇。高能立体系统（H.E.S.S.）天文望远镜最近观测到了来自附近低光度GRB 190829 A的甚高能量（VHE）辐射。后续观察，例如，Swift-XRT，揭示了在1003秒时不寻常的耀斑活动，这可能是由一个长时间的中央发动机引起的。结果表明，在H.E.S.S.观测时间是自然产生的外部逆康普顿（EIC）的情况下，种子光子提供的耀斑或其他后期耗散是向上散射的VHE能量的非热电子加速在外部前向冲击。我们的计算表明，EIC耀斑几乎与晚瞬发耀斑同时发生，但其持续时间比晚瞬发耀斑长1.3 -4倍。在我们的模型中使用的首选动能和初始洛伦兹因子分别为1052 erg和1020 erg。了解低光度伽玛暴VHE辐射的机制有助于我们对外流和中央引擎活动的性质以及粒子加速机制进行约束。
The detection of TeV gamma-ray bursts (GRBs) brought new opportunities for studying the physics of particle acceleration at relativistic shocks. The High Energy Stereoscopic System (H.E.S.S.) telescopes recently observed very-high-energy (VHE) emission from a nearby low-luminosity GRB, GRB 190829A. Follow-up observations with, e.g., Swift-XRT, revealed unusual flare activities at ∼103 s, which can be caused by a long-lasting central engine. We show that the VHE emission during the H.E.S.S. observation time is naturally produced in the external inverse-Compton (EIC) scenario, where seed photons supplied by the flares or other late-time dissipations are upscattered to VHE energies by the nonthermal electrons accelerated at the external forward shock. Our calculations show that the EIC flare nearly coincides with the late-prompt flare, but extends ∼3–4 times longer than the duration of the late-prompt flare. The preferred kinetic energy and initial Lorentz factor used in our model are ∼1052 erg and ∼20, respectively. Understanding the mechanisms of the VHE emission from low-luminosity GRBs will help us constrain the properties of the outflow and the central engine activities, as well as the particle acceleration mechanism.