标题： 压力支持系统的维里质量估计器的系统性 显示英文标题

标题： Systematics in virial mass estimators for pressure-supported systems

摘要： 质量估计器是推断压力支持系统中暗物质含量的关键工具，例如矮椭球星系（dSphs）。我们基于维里定理构建了一个封闭质量的估计器，该估计器对速度弥散的各向异性不敏感，并且经过调整以在我们对（i）内部晕结构的形状和（ii）恒星成分嵌入晕中的深度的不了解的情况下，产生最小不确定性的质量：$M(<1.8\,R_\mathrm{h}) \approx 3.5 \times 1.8\,R_\mathrm{h} \langle \sigma_\mathrm{los}^2 \rangle G^{-1}$，其中$R_\mathrm{h}$表示投影半光半径，$\langle \sigma_\mathrm{los}^2 \rangle$表示光度平均的视线速度弥散平方。与受控模拟的测试表明，该估计器能提供无偏的封闭质量，准确度为$\sim 10$个百分点。这证实了之前提出的类似质量估计器的鲁棒性。应用于已发表的银河系dSph动力学数据揭示了封闭质量与光度之间的紧密相关性。使用$N$体模型，我们表明潮汐剥离对该关系影响很小。与从Aquarius A2并合树的受控再模拟中提取的尖锐核心和核心暗物质晕进行比较显示，超暗弱星系的高质量密度与大的暗物质核心不相容，并且目前经典银河系dSph的（总）晕质量范围非常狭窄（$8 \lesssim \mathrm{log_{10}}\,(M/\mathrm{M_\odot}) \lesssim 10$），显示出与星系大小或光度没有明显的趋势。 显示英文摘要

摘要： Mass estimators are a key tool to infer the dark matter content in pressure-supported systems like dwarf spheroidal galaxies (dSphs). We construct an estimator for enclosed masses based on the virial theorem which is insensitive to anisotropy in the velocity dispersion and tailored to yield masses with minimum uncertainty introduced by our ignorance on (i) the shape of the inner halo profile, and (ii) how deeply the stellar component is embedded within the halo: $M(<1.8\,R_\mathrm{h}) \approx 3.5 \times 1.8\,R_\mathrm{h} \langle \sigma_\mathrm{los}^2 \rangle G^{-1}$, where by $R_\mathrm{h}$ we denote the projected half-light radius and by $\langle \sigma_\mathrm{los}^2 \rangle$ the luminosity-averaged squared line-of-sight velocity dispersion. Tests against controlled simulations show that this estimator provides unbiased enclosed masses with an accuracy of $\sim 10$ per cent. This confirms the robustness of similar previously proposed mass estimators. Application to published kinematic data of Milky Way dSphs reveals a tight correlation between enclosed mass and luminosity. Using $N$-body models we show that tidal stripping has little effect on this relation. Comparison against cuspy and cored dark matter haloes extracted from controlled re-simulations of the Aquarius A2 merger tree shows that the high mass densities of ultrafaint galaxies are not compatible with large dark matter cores, and that the (total) halo masses of the classical Milky Way dSphs span a remarkably narrow range ($8 \lesssim \mathrm{log_{10}}\,(M/\mathrm{M_\odot}) \lesssim 10$) at present, showing no clear trend with either galaxy size or luminosity.