论文标题
轨道上心和卫星星系的暗物质光环结构
Orbital pericenters and the inferred dark matter halo structure of satellite galaxies
论文作者
论文摘要
使用银河系大小的光环仿真的Phat-Elvis套件，我们表明Subhalo Orbital Certenters $ r _ {\ rm Peri} $与它们的暗物质光环结构属性相关。具体来说，以固定的最大圆速度，$ v _ {\ rm max} $，较小的$ r _ {\ rm peri} $的subhalos更加集中（具有较小的$ r _ {\ rm max max} $值），质量更大，较大的峰值峰值，$ v _ peep feep feep fepal} $ peam} $，feep fepal}。这些趋势提供的信息可以收紧有关已知银河系卫星的推断$ v _ {\ rm max} $和$ v _ {\ rm peak} $值的约束。我们使用盖亚（Gaia）对九种矮小球形卫星实现的已发表的捕菜估计来说明了这一点。两个最密集的DSPH卫星（Draco和Ursa Minor）具有相对较小的候选物，这推动了其推断的$ r _ {\ rm max} $和$ v _ {\ rm max} $值低于他们没有候选器信息的低。对于Draco，我们推断$ v _ {\ rm max} = 23.5 \，\ pm 3.3 $ km s $^{ - 1} $（相比之下，$ 27.3 \，\ pm 7.1 $ km s $ s $^{ - 1} $，而无需居中信息）。这种转变加剧了传统的太大而无法失败的问题。 Draco的峰值圆速度范围从$ v _ {\ rm peak} = 21-49 $ km s $^{ - 1} $从$ v _ {\ rm peak} = $ v _ {\ rm peacs} = 25-37 $ km s $ s $ s $^{ - 1} $。在整个古典矮人球体中，我们发现今天$ v _ {\ rm peak} $和恒星质量之间没有相关性，这表明在$ \ sim 10^7 $ m $ _ \ odot $的星形质量的星系形成中存在高水平的随机性。随着矮卫星的适当运动测量变得更加精确，它们应使有用的先验对其宿主暗物质Subhalos的预期结构和演变。
Using the phat-ELVIS suite of Milky Way-size halo simulations, we show that subhalo orbital pericenters, $r_{\rm peri}$, correlate with their dark matter halo structural properties. Specifically, at fixed maximum circular velocity, $V_{\rm max}$, subhalos with smaller $r_{\rm peri}$ are more concentrated (have smaller $r_{\rm max}$ values) and have lost more mass, with larger peak circular velocities, $V_{\rm peak}$, prior to infall. These trends provide information that can tighten constraints on the inferred $V_{\rm max}$ and $V_{\rm peak}$ values for known Milky Way satellites. We illustrate this using published pericenter estimates enabled by Gaia for the nine classical Milky Way dwarf spheroidal satellites. The two densest dSph satellites (Draco and Ursa Minor) have relatively small pericenters, and this pushes their inferred $r_{\rm max}$ and $V_{\rm max}$ values lower than they would have been without pericenter information. For Draco, we infer $V_{\rm max} = 23.5 \, \pm 3.3$ km s$^{-1}$ (compared to $27.3 \, \pm 7.1$ km s$^{-1}$ without pericenter information). Such a shift exacerbates the traditional Too Big to Fail problem. Draco's peak circular velocity range prior to infall narrows from $V_{\rm peak} = 21 - 49$ km s$^{-1}$ without pericenter information to $V_{\rm peak} = 25-37$ km s$^{-1}$ with the constraint. Over the full population of classical dwarf spheroidals, we find no correlation between $V_{\rm peak}$ and stellar mass today, indicative of a high level of stochasticity in galaxy formation at stellar masses below $\sim 10^7$ M$_\odot$. As proper motion measurements for dwarf satellites become more precise, they should enable useful priors on the expected structure and evolution of their host dark matter subhalos.
