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arXiv 0803.0556astro-ph
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用薄盘引力模型描述的银河系自转

Galactic Rotation Described with Thin-Disk Gravitational Model

James Q. Feng, C. F. Gallo

摘要:

用一个由有限半径轴对称薄盘组成的引力模型成功地描述了成熟旋涡星系自转速度的实测剖面。假设圆盘均匀薄,但径向质量密度可变。控制积分方程是基于牛顿引力和离心力(由于星系旋转)之间的机械平衡,在一组有限的同心环的每一点。无量纲的数学系统包含一个无量纲的参数,我们称之为“银河系旋转参数”,它简明地体现了观点。计算的解决方案,满足测量的旋转速度分布的径向质量分布。连同质量守恒的约束方程,银河系的旋转参数也被确定,从测量的银河系半径和最大旋转速度计算银河系的总质量。这些计算出的星系总质量与数据吻合得很好。我们推导出的银河系中央核心的质量分布呈指数递减,与几乎所有其他的结果一致。然而,我们的质量分布在银河系外围有所不同,这些外盘区域的重子质量更普通,温度更低,不透明度/发射率更低(因此更暗)。

英文摘要:

The measured rotation velocity profiles of mature spiral galaxies are successfully described with a gravitational model consisting of a thin axisymmetric disk of finte radius. The disk is assumed uniformly thin but with variable radial mass density. The governing integral equation is based on mechanical balance between Newtonian gravitational and centrifugal forces (due to galaxy rotation) at each and every point in a finite set of concentric rings. The nondimensionalized mathematical system contains a dimensionless parameter we call ``galactic rotation parameter'' which concisely crystallizes perspective. Computational solutions are obtained for the radial mass distributions that satisfy the measured rotational velocity profiles. Together with a constraint equation for mass conservation, the galactic rotational parameter is also determined from which the total galactic mass is calculated from measured galactic radii and maximum rotation velocities. These calculated total galactic masses are in good agreement with data. Our deduced exponentially decreasing mass distributions in the central galactic core are in agreement with almost all others. However our mass distributions differ toward the galactic periphery with more ordinary baryonic mass in these outer disk regions which are cooler with lower opactiy/emissivity (and thus darker).

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。

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