论文标题
测量来自恒星速度分散谱的暗物质光环的质量和浓度
Measuring the mass and concentration of dark matter halos from the velocity dispersion profile of their stars
论文作者
论文摘要
我们使用星系形成的Illustristng（TNG）宇宙学，流体动力学模拟来测量银色质量，星系组和集群尺度的暗物质晕光的暗物质和恒星颗粒的速度分散曲线。从黑暗和发光的示踪剂计算出的平均轮廓的形状相似，在平均轮廓周围表现出很大程度的光环到距离散射。 The so-called "splashback" radius demarcates the outer boundary of the halo, and manifests as a kink in the velocity dispersion profile, located on average between $\sim 1.0-1.5r_{200m}$, where $r_{200m}$ is the radius within which the enclosed density of the halo equals 200 times the mean background density of the universe at that redshift.有趣的是，我们发现该位置也可以被确定为（堆叠）速度分散曲线的半径，降至其峰值的60％（对于TNG Halos中恒星和暗物质颗粒的视线动作）。我们进一步表明，速度分散曲线中的散射可能归因于宿主光晕的组装历史的变化。特别是，这将配置文件分为两个制度：一个在$ \ sim0.1r_ {200m} $之内，其中速度分散体内的散布是由光环的早期组装历史记录设置的，另一个超出了此半径，其中速度分散的散布会受到其后期时间的强烈影响。最后，我们表明，两参数模型可用于拟合测得的速度分散曲线，并且拟合参数可以直接与两个基本光环特性直接相关：质量和浓度。我们描述了一个简单的模型，该模型使我们能够以主机光环的质量和浓度作为唯一的自由参数来表达恒星速度分散曲线。
We use the IllustrisTNG (TNG) cosmological, hydrodynamical simulations of galaxy formation to measure the velocity dispersion profiles of dark matter and star particles in Milky Way-mass, galaxy group, and cluster-scale dark matter halos. The mean profile calculated from both dark and luminous tracers are similar in shape, exhibiting a large degree of halo-to-halo scatter around the average profile. The so-called "splashback" radius demarcates the outer boundary of the halo, and manifests as a kink in the velocity dispersion profile, located on average between $\sim 1.0-1.5r_{200m}$, where $r_{200m}$ is the radius within which the enclosed density of the halo equals 200 times the mean background density of the universe at that redshift. Interestingly, we find that this location may also be identified as the radius at which the (stacked) velocity dispersion profile drops to 60% of its peak value (for line-of-sight motions of stellar and dark matter particles in TNG halos). We further show that the scatter in the velocity dispersion profiles may be attributed to the variations in the assembly history of the host halos. In particular, this segregates the profile into two regimes: one within $\sim0.1r_{200m}$, where the scatter in the velocity dispersion within is set by the early assembly history of the halo, and the other beyond this radius where the scatter in the velocity dispersion is influenced more strongly by its late-time assembly. Finally, we show that a two-parameter model can be used to fit the measured velocity dispersion profiles and the fit parameters can be related directly to two fundamental halo properties: mass and concentration. We describe a simple model which allows us to express the stellar velocity dispersion profile in terms of the mass and concentration of the host halo as the only free parameters.
