Effects of Preionization in Radiative Shocks. I. Self-consistent Models
Effects of Preionization in Radiative Shocks. I. Self-consistent Models
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DOI：
10.3847/1538-4365/aa6541
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发表时间：
2017-02
期刊：
影响因子：
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通讯作者：
R. Sutherland;M. Dopita
中科院分区：
文献类型：
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作者：
R. Sutherland;M. Dopita
在本文中，我们以自洽的方式处理速度范围 10 < vs < 1500 km s−1 的冲击中的预电离问题。我们确定了由冲击前体参数 的值控制的四种不同类别的解决方案，其中 是逃逸到上游的紫外光子的电离参数。该参数决定了进入冲击器的气体的温度和电离程度。在速度增加时，激波解方案是冷中性前驱体（vs ≲ 40 km s−1）、暖中性前驱体（40 ≲ vs ≲ 75 km s−1）、暖部分电离前驱体（75 ≲ vs ≲ 120 km s−1）和快速激波，其中预激波气体处于光电离平衡并完全电离。磁场的主要作用是将这些速度范围推至更高的值并限制震后压缩。为了便于与冲击观测结果进行比较，我们提供了许多方便的参数缩放关系，例如冲击后温度、压缩系数、冷却长度以及 Hβ 和 X 射线光度。
In this paper we treat the preionization problem in shocks over the velocity range 10 < vs < 1500 km s−1 in a self-consistent manner. We identify four distinct classes of solutions controlled by the value of the shock-precursor parameter, , where is the ionization parameter of the UV photons escaping upstream. This parameter determines both the temperature and the degree of ionization of the gas entering the shock. In increasing velocity, the shock solution regimes are cold neutral precursors (vs ≲ 40 km s−1), warm neutral precursors (40 ≲ vs ≲ 75 km s−1), warm partly ionized precursors (75 ≲ vs ≲ 120 km s−1), and fast shocks in which the preshock gas is in photoionization equilibrium and is fully ionized. The main effect of a magnetic field is to push these velocity ranges to higher values and to limit the postshock compression. In order to facilitate comparison with observations of shocks, we provide a number of convenient scaling relationships for parameters, such as postshock temperature, compression factors, cooling lengths, and Hβ and X-ray luminosity.