论文标题
关于银河系和M31运动学的收敛
On the Convergence of the Milky Way and M31 Kinematics from Cosmological Simulations
论文作者
论文摘要
银河系的运动学（MW）和M31（当地组的主要星系（LG））可用于估计LG总质量。 M31适当运动的新结果最近已用于改善该估计值。这些结果是基于运动学先验的，有时会使用宇宙学N体模拟进行指导和评估。但是，由于父母模拟的小尺寸引起的有效功率光谱截断，模拟LG类似物的运动学特性可能会偏差。在这里，我们探讨了LG运动学对仿真框大小的依赖性，以争辩宇宙学模拟需要在1 GPC的顺序上大小，以便在LG运动学属性上声称收敛性。使用足够大的模拟，我们发现M31相对于MW的切向速度和径向速度在$ v _ {\ Mathrm {\ Mathrm {tan}} = 105^{+94} _ { - 59} _ { - 59} $ km/s and s and $ km/s and $ km/s and $ v _ { km/s。这项研究强调，必须考虑到父母模拟的大小，仔细解释从N体模拟中得出的LG运动学。
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.
