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arXiv 2311.06451astro-ph.HE
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探测伽马射线暴余辉中的热电子

Probing Thermal Electrons in GRB Afterglows

Hao-Xuan Gao, Jin-Jun Geng, Tian-Rui Sun, Liang Li, Yong-Feng Huang, Xue-Feng Wu

AI总结:

本文通过求解电子连续性方程并考虑同步辐射等过程,研究GRB余辉中热电子的观测效应,发现热电子会导致多波段谱指数和时间指数非单调变化,并显著提高软硬X射线峰值流量比和时间延迟的上限。

摘要:

粒子模拟(particle-in-cell)已揭示,激波加速的电子并不遵循纯幂律分布,而是具有一个额外的低能“热”成分,该成分占有电子总能量的相当大一部分。研究这些热电子对伽马射线暴(GRB)余辉的影响,可能为粒子加速机制提供有价值的见解。我们求解能量空间中电子的连续性方程,并在此基础上结合同步辐射、同步自吸收、同步自康普顿散射和伽马-伽马湮灭等过程,推导出多波段余辉。首先,由于电子的冷却,时间指数和谱指数之间存在一个潜在的正相关关系。此外,热电子会导致多波段谱指数和时间指数同时出现非单调变化,这种变化可分别由2.5米宽视场巡天望远镜(Wide Field Survey Telescope)和薇拉·鲁宾天文台时空遗产巡天(Vera Rubin Observatory Legacy Survey of Space and Time,LSST)单独记录。通过光学波段(利用LSST)和X射线波段(利用空间变源监测器上的微通道X射线望远镜,Microchannel X-ray Telescope on board the Space Variable Objects Monitor)的协同观测,也可以从余辉光谱中诊断热电子。最后,我们利用蒙特卡洛模拟获得了软X射线与硬X射线之间峰值流量比($R_{\ m X}$)的分布,以及软X射线与光学光变曲线峰值时间之间的时间延迟($Δt$)分布。热电子显著提高了$R_{\ m X}$和$Δt$的上限。因此,具有热电子的GRB余辉分布在$R_{\ m X} - Δt$平面上更加弥散。

英文摘要:

Particle-in-cell simulations have unveiled that shock-accelerated electrons do not follow a pure power-law distribution, but have an additional low-energy "thermal" part, which owns a considerable portion of the total energy of electrons. Investigating the effects of these thermal electrons on gamma-ray burst (GRB) afterglows may provide valuable insights into the particle acceleration mechanisms. We solve the continuity equation of electrons in the energy space, from which multi-wavelength afterglows are derived by incorporating processes including synchrotron radiation, synchrotron self-absorption, synchrotron self-Compton scattering, and gamma-gamma annihilation. First, there is an underlying positive correlation between temporal and spectral indices due to the cooling of electrons. Moreover, thermal electrons would result in the simultaneous non-monotonic variation in both spectral and temporal indices at multi-wavelength, which could be individually recorded by the 2.5-meter Wide Field Survey Telescope and Vera Rubin Observatory Legacy Survey of Space and Time (LSST). The thermal electrons could also be diagnosed from afterglow spectra by synergy observation in the optical (with LSST) and X-ray bands (with the Microchannel X-ray Telescope on board the Space Variable Objects Monitor). Finally, we use Monte Carlo simulations to obtain the distribution of peak flux ratio ($R_{\rm X}$) between soft and hard X-rays, and of the time delay ($Δt$) between peak times of soft X-ray and optical light curves. The thermal electrons significantly raise the upper limits of both $R_{\rm X}$ and $Δt$. Thus the distribution of GRB afterglows with thermal electrons is more dispersive in the $R_{\rm X} - Δt$ plane.

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。

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