非球性对用Schwarzschild方法测量dSph星系质量和各向异性的影响
The effect of non-sphericity on mass and anisotropy measurements in dSph galaxies with Schwarzschild method
摘要：
在我们以前的工作中，我们证实了球对称史瓦西轨道叠加方法恢复球形矮星系的质量和速度各向异性配置文件的可靠性。在这里，我们调查的影响，其应用程序本质上非球形物体。为了这个目的，我们使用一个模型的矮球状星系形成的一个主要合并的两个盘状矮星的数值模拟。合并残余物的恒星成分的形状是轴对称和长扁长的，这使我们能够识别和测量沿不同方向，特别是最长和最短的主轴观测球状星系所造成的偏差。建模是基于模拟数据产生的残余，是观测提供的矮星：投影位置和视线速度的恒星。为了获得一个可靠的工具，同时保持参数的数量低，我们参数化的总质量分布作为一个半径依赖的质光比只有两个自由参数，我们的目标是约束。我们的研究表明，如果总密度分布是已知的，真实的，径向增加的各向异性分布可以很好地恢复沿最长轴的观测，而沿最短轴的数据导致推断一个不正确的，各向同性的模型。另一方面，如果密度分布也是从该方法导出的，则各向异性总是被低估，但是对于沿着最短轴的数据，总质量分布被很好地恢复，而对于最长轴，质量含量被高估。
英文摘要：
In our previous work we confirmed the reliability of the spherically symmetric Schwarzschild orbit-superposition method to recover the mass and velocity anisotropy profiles of spherical dwarf galaxies. Here we investigate the effect of its application to intrinsically non-spherical objects. For this purpose we use a model of a dwarf spheroidal galaxy formed in a numerical simulation of a major merger of two disky dwarfs. The shape of the stellar component of the merger remnant is axisymmetric and prolate which allows us to identify and measure the bias caused by observing the spheroidal galaxy along different directions, especially the longest and shortest principal axis. The modelling is based on mock data generated from the remnant that are observationally available for dwarfs: projected positions and line-of-sight velocities of the stars. In order to obtain a reliable tool while keeping the number of parameters low we parametrize the total mass distribution as a radius-dependent mass-to-light ratio with just two free parameters we aim to constrain. Our study shows that if the total density profile is known, the true, radially increasing anisotropy profile can be well recovered for the observations along the longest axis whereas the data along the shortest axis lead to the inference an incorrect, isotropic model. On the other hand, if the density profile is derived from the method as well, the anisotropy is always underestimated but the total mass profile is well recovered for the data along the shortest axis whereas for the longest axis the mass content is overestimated.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
