标题： 银河系卫星星系的径向分布的时间演化 显示英文标题

标题： Temporal Evolution of the Radial Distribution of Milky Way Satellite Galaxies

摘要： 银河系（MW）周围有几十个卫星星系，其中超过80%的星系具有六维（6D）相空间信息的测量值。 这些卫星的空间分布是星系形成的重要探针，也是绘制银河系潜在暗物质分布的关键手段。 利用已知银河系卫星的测量6D相空间信息，我们在联合银河系+麦哲伦云（LMC）势场中计算轨道历史，包括LMC对所有卫星、银河系质心以及两个星系间潮汐摩擦的动力学影响，以研究银河系累积径向分布的演化过程。 我们得出结论，在考虑LMC引力影响和LMC相关卫星的群落坠入时，径向分布随着时间推移变得更加集中。 与最近对附近类似银河系系统的调查相比，银河系的径向分布在当今、10亿年前和20亿年前都更加集中。 与宇宙学大尺度模拟中的银河系质量宿主相比，我们发现银河系的径向分布也比模拟的对应物更集中；然而，在LMC坠入之前20亿年时，模拟结果与我们对银河系卫星分布的分析之间存在一定程度的重叠。 最后，我们认为，那些模拟出的具有LMC伴星的银河系质量类似星系，其径向分布也可能以相似的方式演化，即一个巨大卫星及其卫星的吸积会导致径向分布随着巨大卫星接近其宿主星系而变得更加集中。 显示英文摘要

摘要： The Milky Way (MW) is surrounded by dozens of satellite galaxies, with six-dimensional (6D) phase space information measured for over 80% of this population. The spatial distribution of these satellites is an essential probe of galaxy formation and for mapping the MW's underlying dark matter distribution. Using measured 6D phase space information of known MW satellites, we calculate orbital histories in a joint MW+LMC potential, including the gravitational influence of the LMC on all satellites, on the MW's center of mass, and dynamical friction owing to both galaxies, to investigate the evolution of the MW's cumulative radial profile. We conclude radial profiles become more concentrated over time when we consider the LMC's gravitational influence and the group infall of LMC-associated satellites. The MW's radial distribution is consistently more concentrated at present-day, 1 Gyr, and 2 Gyr ago compared to recent surveys of nearby MW-like systems. Compared to MW-mass hosts in cosmological, zoom-in simulations, we find the MW's radial profile is also more concentrated than those of simulated counterparts; however, some overlap exists between simulation results and our analysis of the MW's satellite distribution 2 Gyr ago, pre-LMC infall. Finally, we posit radial profiles of simulated MW-mass analogs also hosting an LMC companion are likely to evolve similarly to our results, such that the accretion of a massive satellite along with its satellites will lead to a more concentrated radial profile as the massive satellite advances toward its host galaxy.