arXiv 2209.093692022-09-19astro-ph.COastro-ph.GA

从宇宙学模拟看Milky Way和M31动力学的收敛性

On the Convergence of the Milky Way and M31 Kinematics from Cosmological Simulations

J. E. Forero-Romero, D. Sierra-Porta

备注：: 7 pages, 4 figures, Accepted for publication in ApJ

摘要：

银河系（MW）和M31（本星系群中的主要星系）的运动学可以用来估计本星系群的总质量。关于M31自行的新结果最近被用来改进这一估计。这些结果是基于运动学先验，有时使用宇宙学N体模拟进行指导和评估。然而，模拟LG类似物的运动学特性可能会有偏差，由于有效的功率谱截断引起的小尺寸的父模拟。在这里，我们探讨的依赖LG运动学的模拟框的大小，认为宇宙学模拟需要一个框的大小为1 Gpc的顺序，以索赔收敛的LG运动学性质。使用足够大的模拟，我们发现M31相对于MW的切向和径向速度分别在$v_{\mathrm {tan}}=105^{+94}_{-59} $ km/s和$v_{\mathrm {rad}}=-108^{+68}_{-81}$ km/s的范围内。这项研究强调，LG运动学来自N体模拟必须仔细解释考虑到父模拟的大小。

英文摘要：

The kinematics of the Milky Way (MW) and M31, the dominant galaxies in the Local Group (LG), can be used to estimate the LG total mass. New results on the M31 proper motion have recently been used to improve that estimate. Those results are based on kinematic priors that are sometimes guided and evaluated using cosmological N-body simulations. However, the kinematic properties of simulated LG analogues could be biased due to the effective power spectrum truncation induced by the small size of the parent simulation. Here we explore the dependence of LG kinematics on the simulation box size to argue that cosmological simulations need a box size on the order of 1 Gpc in order to claim convergence on the LG kinematic properties. Using a large enough simulation, we find M31 tangential and radial velocities relative to the MW to be in the range $v_{\mathrm {tan}}=105^{+94}_{-59} $ km/s and $v_{\mathrm {rad}}=-108^{+68}_{-81}$ km/s, respectively. This study highlights that LG kinematics derived from N-body simulations have to be carefully interpreted taking into account the size of the parent simulation.

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