Magnetically driven coupling in relativistic radiation-mediated shocks
Magnetically driven coupling in relativistic radiation-mediated shocks
复制标题
相对论辐射介导冲击中的磁驱动耦合
DOI：
10.1093/mnras/stad064
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发表时间：
2023
影响因子：
4.8
通讯作者：
Fiuza, F.
中科院分区：
文献类型：
--
作者：
Mahlmann, J. F.;Vanthieghem, A.;Philippov, A. A.;Levinson, A.;Nakar, E.;Fiuza, F.
在宇宙爆炸的富光子环境中，辐射阻力可以通过诱导相对论流动等离子体成分之间的速度差来引发动力学不稳定性。这种微湍流很可能是辐射介导的冲击爆发信号的印记。然而，大规模的，横向磁场的激波过渡的减速区可以抑制占主导地位的动力学不稳定性，防止电子-正电子对和重离子物种之间的速度分离的发展。我们使用一个一维五流体辐射传输代码来产生自洽的配置文件的辐射阻力和等离子体成分的减速区。对于增加磁化，我们的模型预测迅速增长的对多重性和大量的辐射阻力发展自相似的整个减速区。我们提取的临界磁化参数σc，确定的极限磁场强度，在该强度下，三种等离子体可以发展动力学不稳定性，然后到达各向同性下游。对于在相对论辐射介导激波上游以γu= 10漂移的相对论单离子等离子体，我们发现微湍流开始的阈值σc = 10− 7。在多离子组成的情况下，抑制等离子体不稳定性可能需要更高的σc值。识别冲击波爆发信号中微湍流的高能特征，并将其与本工作中提供的磁化极限相结合，将使我们能够更深入地了解宇宙爆炸（如超新星、伽马射线爆发和中子星星双星合并）的磁环境。
The radiation drag in photon-rich environments of cosmic explosions can seed kinetic instabilities by inducing velocity spreads between relativistically streaming plasma components. Such microturbulence is likely imprinted on the breakout signals of radiation-mediated shocks. However, large-scale, transverse magnetic fields in the deceleration region of the shock transition can suppress the dominant kinetic instabilities by preventing the development of velocity separations between electron–positron pairs and a heavy ion species. We use a 1D five-fluid radiative transfer code to generate self-consistent profiles of the radiation drag force and plasma composition in the deceleration region. For increasing magnetization, our models predict rapidly growing pair multiplicities and a substantial radiative drag developing self-similarly throughout the deceleration region. We extract the critical magnetization parameter σc, determining the limiting magnetic field strength at which a three-species plasma can develop kinetic instabilities before reaching the isotropized downstream. For a relativistic, single ion plasma drifting with γu= 10 in the upstream of a relativistic radiation-mediated shock, we find the threshold σc≈ 10−7for the onset of microturbulence. Suppression of plasma instabilities in the case of multi-ion composition would likely require much higher values of σc. Identifying high-energy signatures of microturbulence in shock breakout signals and combining them with the magnetization limits provided in this work will allow a deeper understanding of the magnetic environment of cosmic explosions like supernovae, gamma-ray bursts, and neutron star binary mergers.