The Validity of 21 cm Spin Temperature as a Kinetic Temperature Indicator in Atomic and Molecular Gas
The Validity of 21 cm Spin Temperature as a Kinetic Temperature Indicator in Atomic and Molecular Gas
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21 cm 自旋温度作为原子和分子气体动力学温度指示器的有效性
DOI：
10.3847/1538-4357/aa7747
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
I. Hubeny
中科院分区：
文献类型：
--
作者：
G. Shaw;G. Shaw;G. Ferland;I. Hubeny
各种星际环境的气体动力学温度(TK)通常是通过谱线观测来推断原子、离子或分子的能级布居的；HI21 cm可能是最广泛使用的，并且有很长的历史。通常假定HI21 cm线处于热平衡状态，布居数服从Boltzmann分布。各种工艺，其中许多涉及Lyα，可能会影响21厘米的线。在这里，我们展示了如何在光谱模拟程序Cloudy中处理这一问题，并对使用这种温度指示器的环境进行了数值模拟，并详细处理了决定H0内能级布居的物理过程。我们讨论了这个温度指示器跟踪Tk的情况，它失败的情况，以及Lyα泵浦对21厘米自旋温度的影响。我们还发现，Lyα激发温度很少跟踪气体动力学温度。
The gas kinetic temperature (TK) of various interstellar environments is often inferred from observations that can deduce level populations of atoms, ions, or molecules using spectral line observations; H i 21 cm is perhaps the most widely used, and has a long history. Usually the H i 21 cm line is assumed to be in thermal equilibrium and the populations are given by the Boltzmann distribution. A variety of processes, many involving Lyα, can affect the 21 cm line. Here we show how this is treated in the spectral simulation code Cloudy, and present numerical simulations of environments where this temperature indicator is used, with a detailed treatment of the physical processes that determine level populations within H0. We discuss situations where this temperature indicator traces TK, cases where it fails, as well as the effects of Lyα pumping on the 21 cm spin temperature. We also show that the Lyα excitation temperature rarely traces the gas kinetic temperature.