标题： 星际介质中磁场强度与气体密度之间的关系：多尺度分析 显示英文标题

标题： On the relation between magnetic field strength and gas density in the interstellar medium: A multiscale analysis

摘要： 星际介质中的磁场强度与气体密度关系具有根本的重要性。 我们提出了对B-n关系的贝叶斯分析，并比较了两个全面观测数据集：一个Zeeman数据集和使用Davis-Chandrasekhar-Fermi（DCF）方法的700次观测。 利用分层贝叶斯分析，我们提出了一般性的、多尺度的分段幂律关系，即 $B=B_0(n/n_0)^{\alpha}$ ，对于 $\alpha=\alpha_1$ 的 $n<n_0$ 和对于 $\alpha_2$ 的 $n>n_0$ ，以及以 $B_0$ 表示 $n_0$ 处的场强。 对于塞曼数据，我们得到：弥散气体的值为$\alpha_1={0.15^{+0.06}_{-0.09}}$，密集气体的值为$\alpha_2 = {0.53^{+0.09}_{-0.07}}$，对应柱密度为$n_0 = 4.00^{+12.7}_{-2.90} \times 10^3$ cm$^{-3}$。 对于DCF数据，我们发现：$\alpha_1={0.26^{+0.15}_{-0.15}}$和$\alpha_2={0.77_{-0.15}^{+0.14}}$，其中$n_0=13.9^{+10.1}_{-7.30} \times 10^4$cm$^{-3}$，不确定性给出了68％的可信区间。 我们在十九个数值磁流体力学模拟上进行了类似的分析，这些模拟涵盖了从原恒星盘到矮星和类似银河系的广泛物理条件，并使用了AREPO、Flash、Pencil和Ramses代码完成。 所得指数取决于多个物理因素，例如发电机效应及其时间尺度、湍流以及初始种子场强度。 \textcolor{red}我们发现矮星和类似银河系的模拟产生的结果最接近观测值。 显示英文摘要

摘要： The magnetic field strength to gas density relation in the interstellar medium is of fundamental importance. We present and compare Bayesian analyses of the B-n relation for two comprehensive observational data sets: a Zeeman data set and 700 observations using the Davis-Chandrasekhar-Fermi (DCF) method. Using a hierarchical Bayesian analysis we present a general, multi-scale broken power-law relation, $B=B_0(n/n_0)^{\alpha}$ , with $\alpha=\alpha_1$ for $n<n_0$ and $\alpha_2$ for $n>n_0$, and with $B_0$ the field strength at $n_0$. For the Zeeman data we find: $\alpha_1={0.15^{+0.06}_{-0.09}}$ for diffuse gas and $\alpha_2 = {0.53^{+0.09}_{-0.07}}$ for dense gas with $n_0 = 4.00^{+12.7}_{-2.90} \times 10^3$ cm$^{-3}$. For the DCF data we find: $\alpha_1={0.26^{+0.15}_{-0.15}}$ and $\alpha_2={0.77_{-0.15}^{+0.14}}$, with $n_0=13.9^{+10.1}_{-7.30} \times 10^4$ cm$^{-3}$, where the uncertainties give 68\% credible intervals. We perform a similar analysis on nineteen numerical magnetohydrodynamic simulations covering a wide range of physical conditions from protostellar disks to dwarf and Milky Way-like galaxies, completed with the AREPO, Flash, Pencil, and Ramses codes. The resulting exponents depend on several physical factors such as dynamo effects and their time scales, turbulence, and initial seed field strength. \textcolor{red}{We find that the dwarf and Milky Way-like galaxy simulations produce results closest to the observations.