标题： 视线速度投影对本星系群质量的影响 显示英文标题

标题： Line-of-Sight Velocity Projection Impact on the Local Group Mass

摘要： 本地星系群（LG）的质量，包括银河系（MW）、仙女座星系（M31）及其卫星，对于验证星系形成和宇宙学模型至关重要。传统的基于视线速度和简化下落假设的视星质量估计容易受到未观测到的速度分量和各向异性运动的系统偏差影响。利用TNG宇宙学模拟，我们研究了两种极限情况：忽略视线方向垂直速度的\underline{小规模坍缩}模型和假设纯径向运动朝向质心（CoM）的\underline{主要吸积}模型。我们的模拟表明几何修正至关重要：小规模下落模型低估了真实质量，而大规模下落模型则高估了它。通过将这些校准后的修正应用于本地星系群质心1 Mpc范围内的矮星系动力学观测，我们得出改进的本地星系群质量为$M_{\mathrm{LG}} = (2.99 \pm 0.60) \times 10^{12}\, M_\odot$。这一发现与$\Lambda$冷暗物质模型的预测、时间论证以及独立的质量估算相一致，解决了之前的分歧。我们的分析强调了修正速度各向异性的必要性，并为星系团的动力学质量估算提供了稳健的框架。 显示英文摘要

摘要： The mass of the Local Group (LG), comprising the Milky Way (MW), Andromeda (M31), and their satellites, is crucial for validating galaxy formation and cosmological models. Traditional virial mass estimates, which rely on line-of-sight (LoS) velocities and simplified infall assumptions, are prone to systematic biases due to unobserved velocity components and anisotropic kinematics. Using the TNG cosmological simulation, we examine two limiting cases: the \underline{minor infall} model -- ignoring perpendicular velocities to the LoS directions) and the \underline{major infall} model -- assuming purely radial motion towards the Center of Mass (CoM). Our simulations demonstrate that geometric corrections are vital: the minor-infall model underestimates the true mass, while the major-infall model overestimates it. By applying these calibrated corrections to observed dwarf galaxy kinematics within 1 Mpc of the LG's CoM, we derive a refined LG mass of $M_{\mathrm{LG}} = (2.99 \pm 0.60) \times 10^{12}\, M_\odot$. This finding aligns with predictions from the $\Lambda$CDM model, timing arguments, and independent mass estimates, resolving previous discrepancies. Our analysis highlights the importance of correcting for velocity anisotropy and offers a robust framework for dynamical mass estimation in galaxy groups.