Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
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DOI：
10.1111/j.1365-2966.2008.13754.x
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发表时间：
2008-05
影响因子：
4.8
通讯作者：
M. Cappellari
中科院分区：
文献类型：
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作者：
M. Cappellari
我们提出了一个简单而有效的各向异性推广的半各向同性（两个积分）轴对称的Jeans形式主义，这是用来模拟星系的恒星运动学。假设如下：（i）恒定的质光比（MIL）和（ii）与柱坐标（R，z）对齐的速度椭球，其特征在于经典的各向异性参数β z = 1 -λ 2 z /λ 2 R。我们的简单模型适合于一组快旋早型星系的恒星运动学的SAURON积分场观测。在只有两个自由参数（β z和倾角）的情况下，一旦给出了表面亮度的详细描述，模型通常能很好地描述第一（V）和第二（Vrms）速度矩V2 + σ 2的形状。这与以前对这些物体的动力学结构的发现是一致的。该方法在假设β z ≥0的情况下，能够恢复出倾斜角。该技术可用于确定早期类型的快速旋转星系和螺旋星系的动态MIL和角动量，特别是当数据的质量不证明更复杂的建模方法。这种形式主义允许包括暗物质，超大质量黑洞，空间变化的各向异性和多个运动学组件。
We present a simple and efficient anisotropic generalization of the semi-isotropic (two-integral) axisymmetric Jeans formalism, which is used to model the stellar kinematics of galaxies. The following is assumed: (i) a constant mass-to-light ratio (MIL) and (ii) a velocity ellipsoid that is aligned with cylindrical coordinates (R, z) and characterized by the classic anisotropy parameter β z = 1 - υ 2 z /υ 2 R . Our simple models are fit to SAURON integral-field observations of the stellar kinematics for a set of fast-rotator early-type galaxies. With only two free parameters (β z and the inclination), the models generally provide remarkably good descriptions of the shape of the first (V) and second (V rms ≡ √V 2 + σ 2 ) velocity moments, once a detailed description of the surface brightness is given. This is consistent with previous findings on the dynamical structure of these objects. With the observationally motivated assumption that β z ≥0, the method is able to recover the inclination. The technique can be used to determine the dynamical MIL and angular momenta of early-type fast-rotators and spiral galaxies, especially when the quality of the data does not justify more sophisticated modelling approaches. This formalism allows for the inclusion of dark matter, supermassive black holes, spatially varying anisotropy and multiple kinematic components.