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arXiv 2212.00765astro-ph.HE
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高能伽马射线暴的多碰撞内激波轻子-强子模型

Multi-collision internal shock lepto-hadronic models for energetic GRBs

Annika Rudolph, Maria Petropoulou, Željka Bošnjak, Walter Winter

AI总结:

本研究针对高能伽马射线暴构建多碰撞内激波轻子-强子模型,分析质子辐射的多波长特征,发现重子负载约为10时符合观测约束,支持大耗散半径下的高能GRB可能是超高能宇宙线的起源。

摘要:

对于一类高能伽马射线暴(GRB)亚群,适度的重子负载可能足以为超高能宇宙线(UHECR)提供能量。受此启发,我们研究了高能GRB瞬时辐射阶段宇宙线质子的辐射特征。我们的研究框架为内激波模型,包含相对论喷流物质的多碰撞描述(沿喷流存在不同的辐射区),并结合了光子与中微子能谱的时变计算。我们的GRB原型以费米-LAT(Fermi-LAT)探测到的GRB(包括GRB 221009A)为参考,由于这类暴的能流很大,未观测到单个中微子事件可能会对重子负载施加很强的限制。我们研究了同步辐射主导和逆康普顿主导两种情景下质子对电磁能谱的反馈,以识别多波长辐射特征、约束最大允许重子负载,并指出强子过程与逆康普顿过程特征的差异。我们发现,在同步辐射情景中,强子特征表现为光学-紫外到软X射线波段以及GeV到TeV伽马射线波段的流量相关增强;而在逆康普顿主导的情景中,这类特征难以识别。我们证明,满足UHECR能量需求的、约为10的重子负载不会扭曲费米-GBM(Fermi-GBM)波段的预测光子能谱,且当碰撞半径足够大(即时变时标不太短)时,与中微子数据的约束一致。因此,在大耗散半径条件下,一类高能GRB可能是UHECR的起源。

英文摘要:

For a sub-population of energetic Gamma-Ray Bursts (GRBs), a moderate baryonic loading may suffice to power Ultra-High-Energy Cosmic Rays (UHECRs). Motivated by this, we study the radiative signatures of cosmic-ray protons in the prompt phase of energetic GRBs. Our framework is the internal shock model with multi-collision descriptions of the relativistic ejecta (with different emission regions along the jet), plus time-dependent calculations of photon and neutrino spectra. Our GRB prototypes are motivated by {\em Fermi}-LAT detected GRBs (including GRB~221009A) for which further, owing to the large energy flux, neutrino non-observation of single events may pose a strong limit on the baryonic loading. We study the feedback of protons on electromagnetic spectra in synchrotron- and inverse Compton-dominated scenarios to identify the multi-wavelength signatures, to constrain the maximally allowed baryonic loading, and to point out the differences between hadronic and inverse Compton signatures. We find that hadronic signatures appear as correlated flux increases in the optical-UV to soft X-ray and GeV to TeV gamma-ray ranges in the synchrotron scenarios, whereas they are difficult to identify in inverse Compton-dominated scenarios. We demonstrate that baryonic loadings around 10, which satisfy the UHECR energetic requirements, do not distort the predicted photon spectra in the {\em Fermi}-GBM range and are consistent with constraints from neutrino data if the collision radii are large enough (i.e., the time variability is not too short). It therefore seems plausible that under the condition of large dissipation radii a population of energetic GRBs can be the origin of the UHECRs.

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