早型星系的质量分布和轨道各向异性：来自质量面的约束
Mass distribution and orbital anisotropy of early-type galaxies: constraints from the Mass Plane
摘要：
观测到大质量早型星系位于质量平面（MP）上，质量平面是一个有效半径为Re，投影质量为M_p（通过强引力透镜测量），投影速度色散σ在Re/2以内的二维流形。MP比基本平面的“倾斜”小，两者具有可比的相关散射。这意味着c_e2=2*G*M_p/（R_e*sigma^2）在sigma=175-400 km/s的范围内几乎是一个普适常数。这一发现可以用来限制早期星系的质量分布和内部动力学。我们发现，一个相对广泛的类球形星系模型的c_e2值在观测范围内，因为c_e2是不是很强的质量分布和轨道各向异性敏感。如果总质量分布是等温的，一个广泛的恒星光度分布和各向异性是与观测相一致的，而NFW暗物质晕需要更多的微调的恒星质量分数，光度分布和各向异性。如果未来的数据可以覆盖更广泛的质量范围，MP可以被视为倾斜的，任何这种倾斜的值将提供星系总质量密度分布模型之间的判别。[删节]
英文摘要：
Massive early-type galaxies are observed to lie on the Mass Plane (MP), a two-dimensional manifold in the space of effective radius R_e, projected mass M_p (measured via strong gravitational lensing) and projected velocity dispersion sigma within R_e/2. The MP is less `tilted' than the Fundamental Plane, and the two have comparable associated scatter. This means that c_e2=2*G*M_p/(R_e*sigma^2) is a nearly universal constant in the range sigma=175-400 km/s. This finding can be used to constrain the mass distribution and internal dynamics of early-type galaxies. We find that a relatively wide class of spherical galaxy models has values of c_e2 in the observed range, because c_e2 is not very strongly sensitive to the mass distribution and orbital anisotropy. If the total mass distribution is isothermal, a broad range of stellar luminosity profile and anisotropy is consistent with the observations, while NFW dark-matter halos require more fine tuning of the stellar mass fraction, luminosity profile and anisotropy. If future data can cover a broader range of masses, the MP could be seen to be tilted and the value of any such tilt would provide a discriminant between models for the total mass-density profile of the galaxies. [Abridged]
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