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arXiv 2408.01722astro-ph.HE
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伽马射线暴中由随机场引起的磁场结构偏振度变化

Polarization degree of magnetic field structure changes caused by random magnetic field in Gamma-ray Burst

Jiang-Chuan Tuo, Hong-Bang Liu, Qian-Nan Mai, Qian Zhong, Zu-Ke Feng, Kang-Fa Cheng, En-Wei Liang

AI总结:

本文构建含随机与有序磁场的PFD喷流模型,计算单脉冲PD曲线,揭示随机场显著降低X射线偏振度并引发两次PA旋转。

摘要:

在呈现有序磁场的坡印廷通量主导(PFD)喷流中,瞬时辐射阶段发生磁重联和能量耗散后,会向湍流和磁无序状态转变。在此过程中,磁场构型随时间演化,使其无法被完全归类为有序磁场。因此,我们采用一个包含随机磁场和有序磁场的粗略模型,并考虑随机磁场强度相对于有序磁场的比例,以计算单个脉冲的偏振度(PD)曲线。研究发现,随机磁场对低能X射线的PD结果具有显著影响。在有序磁场中,即使电子注入停止后,X射线波段相比数百keV和MeV能段仍保持显著的PD,这使PD更易于被偏振测量探测到。然而,当引入随机磁场后,低能和高能PD表现出相似趋势,X射线PD低于高能波段。当然,这与磁场的无序速率有关。此外,还出现了此前不存在的两次偏振角(PA)旋转,且高能波段的PA旋转发生得稍早。这些结果与有序磁场的结构无关。

英文摘要:

In a Poynting-flux-dominated (PFD) jet that exhibits an ordered magnetic field, a transition towards turbulence and magnetic disorder follows after magnetic reconnection and energy dissipation during the prompt emission phase. In this process, the configuration of the magnetic field evolves with time, rendering it impossible to entirely categorize the magnetic field as ordered. Therefore, we assumed a crude model that incorporates a random magnetic field and an ordered magnetic field, and takes into account the proportionality of the random magnetic field strength to the ordered magnetic field, in order to compute the polarization degree (PD) curve for an individual pulse. It has been discovered that the random magnetic field has a significant impact on the PD results of the low-energy X-ray. In an ordered magnetic field, the X-ray segment maintains a significant PD compared to those in the hundreds of keV and MeV ranges even after electron injection ceases, this making PD easier to detect by polarimetry. However, when the random magnetic field is introduced, the low-energy and high-energy PDs exhibit a similar trend, with the X-ray PD being lower than that of the high-energy segment. Of course, this is related to the rate of disorder in the magnetic field. Additionally, there is two rotation of the polarization angles (PAs) that were not present previously, and the rotation of the PA in the high-energy segment occurs slightly earlier. These results are unrelated to the structure of the ordered magnetic field.

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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