Knowing the unknowns : uncertainties in simple estimators of galactic dynamical masses.
Knowing the unknowns : uncertainties in simple estimators of galactic dynamical masses.
复制标题
了解未知数：银河动力质量简单估计的不确定性。
DOI：
10.1093/mnras/stx975
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发表时间：
2016
影响因子：
4.8
通讯作者：
T. Theuns
中科院分区：
文献类型：
--
作者：
D. Campbell;C. Frenk;A. Jenkins;V. Eke;J. Navarro;Till Sawala;M. Schaller;Azadeh Fattahi;K. Oman;T. Theuns
观测到的色散支持星系的恒星运动学通常用于测量动力学质量。最近，基于球面吉恩斯方程，提出了恒星视线速度色散、投影（2D）或投影（3D）半光半径以及半光半径内的总质量之间的几种解析关系。在这里，我们使用本星系群的 APOSTLE 宇宙流体动力学模拟来测试这种质量估计器对于色散和旋转支持的星系、场星系和卫星星系以及不同质量、形状和速度色散各向异性的星系的有效性和准确性。我们发现沃克等人的质量估计量。和沃尔夫等人。能够恢复大量色散主导的系统，几乎没有系统偏差，但 1σ 色散分别为 25% 和 23%。估计质量的误差主要受到恒星质量分布3D形状的影响，这很难通过观测来约束。这种内在的散射成为星系质量估计的不确定性的主要来源，例如银河系的矮椭球体（dSph）卫星，其大小和速度色散的观测误差很小。这种散射还可能影响源自多个恒星群的 dSphs 的内部密度斜率，从而放宽纳瓦罗-弗伦克-怀特剖面可能被排除的重要性，具体取决于不同恒星群的相关属性的相关程度。最后，我们推导了一种新的最佳质量估计器，它消除了残余偏差，并在统计上显着地将色散主导星系的散射减少至 20%，从而实现了更精确和准确的质量估计。
The observed stellar kinematics of dispersion-supported galaxies are often used to measure dynamical masses. Recently, several analytical relationships between the stellar line-of-sight velocity dispersion, the projected (2D) or deprojected (3D) half-light radius and the total mass enclosed within the half-light radius, relying on the spherical Jeans equation, have been proposed. Here, we use the APOSTLE cosmological hydrodynamical simulations of the Local Group to test the validity and accuracy of such mass estimators for both dispersion and rotation-supported galaxies, for field and satellite galaxies, and for galaxies of varying masses, shapes and velocity dispersion anisotropies. We find that the mass estimators of Walker et al. and Wolf et al. are able to recover the masses of dispersion-dominated systems with little systematic bias, but with a 1σ scatter of 25 and 23 per cent, respectively. The error on the estimated mass is dominated by the impact of the 3D shape of the stellar mass distribution, which is difficult to constrain observationally. This intrinsic scatter becomes the dominant source of uncertainty in the masses estimated for galaxies like the dwarf spheroidal (dSph) satellites of the Milky Way, where the observational errors in their sizes and velocity dispersions are small. Such scatter may also affect the inner density slopes of dSphs derived from multiple stellar populations, relaxing the significance with which Navarro–Frenk–White profiles may be excluded, depending on the degree to which the relevant properties of the different stellar populations are correlated. Finally, we derive a new optimal mass estimator that removes the residual biases and achieves a statistically significant reduction in the scatter to 20 per cent overall for dispersion-dominated galaxies, allowing more precise and accurate mass estimates.
DOI：
10.1111/j.1365-2966.2009.15034.x
发表时间：
2008-08
影响因子：
4.8
作者：
K. Dolag;S. Borgani;S. Borgani;S. Borgani;G. Murante;V. Springel
通讯作者：
K. Dolag;S. Borgani;S. Borgani;S. Borgani;G. Murante;V. Springel
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.