Our nearest large cosmological neighbour, the Andromeda galaxy (M31), is a dynamical system, and an accurate measurement of its total mass is central to our understanding of its assembly history, the life-cycles of its satellite galaxies, and its role in shaping the Local Group environment. Here, we apply a novel approach to determine the dynamical mass of M31 using high velocity Planetary Nebulae (PNe), establishing a hierarchical Bayesian model united with a scheme to capture potential outliers and marginalize over tracers unknown distances. With this, we derive the escape velocity run of M31 as a function of galacto-centric distance, with both parametric and non-parametric approaches. We determine the escape velocity of M31 to be $470\pm{40}$ km s$^{-1}$ at a galacto-centric distance of 15 kpc, and also, derive the total potential of M31, estimating the virial mass and radius of the galaxy to be $0.8\pm{0.1}\times10^{12}\,M_\odot$ and $240\pm{10}$ kpc, respectively. Our M31 mass is on the low-side of the measured range, this supports the lower expected mass of the M31-Milky Way system from the timing and momentum arguments, satisfying the HI constraint on circular velocity between $10\lesssim R/\textrm{kpc}<35$, and agreeing with the stellar mass Tully-Fisher relation. To place these results in a broader context, we compare them to the key predictions of the $\Lambda{\rm CDM}$ cosmological paradigm, including the stellar-mass-halo-mass and the dark matter halo concentration-virial mass correlation, and finding it to be an outlier to this relation.
翻译：我们最接近的宇宙邻国安卓美达星系(M31)是一个动态系统,精确测量其总质量对于我们了解其组装史、卫星星系生命周期及其影响本地组环境的作用至关重要。在这里,我们采用一种新颖的方法,使用高速行星星云(Pne)来确定M31的动态质量,建立一个高层次的巴伊西亚模型,用一个办法来捕捉潜在外星和在未知距离外的跟踪者。有了这个系统,我们得出M31的逃逸速度运行是星际中心距离、卫星星系星际周期周期以及非参数的函数。我们确定M31的逃逸速度是470美元/pm{40美元/m s%_1美元,同时得出M31的总潜力,估计星系的星际质量质量和半径范围是0.8/pm@%%c=10,目前测得的轨距为Sloral-cal-cal-clusal 和Mral-ral-ral-ral-ral-ral-ral-ral-ral-ral-ral-ral-ral ral-ral-ral-ral-ral-ral-ral-ral-ral-ral-ral-l-l-l-l-l-l-l-l-l-l-l-l-l-l-s-s-s-s-s-s-s-s-s-lx-lus-lx-l-l-l-l-lx-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l
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