打破beta:球面系统质量建模方法的比较

J. Read, G. Mamon, E. Vasiliev, E. Vasiliev, E. Vasiliev, Laura L. Watkins, Laura L. Watkins, Laura L. Watkins, M. Walker, J. P. narrubia, M. Wilkinson, W. Dehnen, W. Dehnen, Payel Das, Payel Das
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引用次数: 13

摘要

我们将四种不同的质量建模方法应用于一套公开可用的球形恒星系统模拟数据。我们的重点是恢复密度和速度各向异性作为半径的函数,要么只使用视线速度数据,要么添加适当的运动数据。所有方法在各向同性和切向各向异性模拟数据上都表现良好,在径向范围0.25 < R/Rhalf < 4(其中Rhalf为半光半径)的95%置信区间内恢复密度和速度各向异性。然而,径向各向异性模型更具挑战性。仅对于视距数据,只有使用速度分布函数形状信息的方法才能打破密度剖面和速度各向异性之间的简并,从而获得两者的无偏估计。这种形状信息可以通过直接拟合全局相空间分布函数、使用高阶“维里形状参数”、或者通过局部假设高斯速度分布函数,但沿着视线自一致地投射它来获得。包括适当的运动数据可以进一步改进,在这种情况下,所有方法都可以很好地恢复径向密度和速度各向异性剖面。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Breaking beta: a comparison of mass modelling methods for spherical systems
We apply four different mass modelling methods to a suite of publicly available mock data for spherical stellar systems. We focus on the recovery of the density and velocity anisotropy as a function of radius, using either line-of-sight velocity data only, or adding proper motion data. All methods perform well on isotropic and tangentially anisotropic mock data, recovering the density and velocity anisotropy within their 95% confidence intervals over the radial range 0.25 < R/Rhalf < 4, where Rhalf is the half light radius. However, radially-anisotropic mocks are more challenging. For line-of-sight data alone, only methods that use information about the shape of the velocity distribution function are able to break the degeneracy between the density profile and the velocity anisotropy to obtain an unbiased estimate of both. This shape information can be obtained through directly fitting a global phase space distribution function, by using higher order 'Virial Shape Parameters', or by assuming a Gaussian velocity distribution function locally, but projecting it self-consistently along the line of sight. Including proper motion data yields further improvements, and in this case, all methods give a good recovery of both the radial density and velocity anisotropy profiles.
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