暗物质主导矮盘星系Segue 1
Dark matter dominated dwarf disc galaxy Segue 1
摘要：
几次观测显示，矮星系Segue 1有一个暗物质（DM）晕，其质量至少是其可见重子质量（约103个太阳质量）的200倍。重子质量主要是由星际气体质量可能小于13个太阳质量的恒星决定的。考虑Segue 1作为一个矮盘星系的形态外观的长拉伸，我们调用Xiang-Gruess，Lou和Duschl（XLD）的动力学模型，以估计其可能的平衡的物理参数，并没有一个等径磁化的气体盘。我们估计DM质量的范围，并将其与现有的观察推断进行比较。由于相对较高的恒星速度色散相比，恒星表面的质量密度，我们发现，一个大规模的DM晕将是必要的，以维持光盘平衡。到目前为止，所需的DM晕质量与观测推断大体一致。对于气盘中的等序磁场，DM势与重子势之比f强烈地依赖于磁场强度。因此，需要一个大质量的DM晕来抵消强烈的恒星速度色散和旋转的恒星盘或磁洛伦兹力的气体盘。通过径向力平衡，DM晕质量增加以获得更快的盘旋转。
英文摘要：
Several observations reveal that dwarf galaxy Segue 1 has a dark matter (DM) halo at least ~ 200 times more massive than its visible baryon mass of only ~ 103 solar masses. The baryon mass is dominated by stars with perhaps an interstellar gas mass of < 13 solar masses. Regarding Segue 1 as a dwarf disc galaxy by its morphological appearance of long stretch, we invoke the dynamic model of Xiang-Gruess, Lou & Duschl (XLD) to estimate its physical parameters for possible equilibria with and without an isopedically magnetized gas disc. We estimate the range of DM mass and compare it with available observational inferences. Due to the relatively high stellar velocity dispersion compared to the stellar surface mass density, we find that a massive DM halo would be necessary to sustain disc equilibria. The required DM halo mass agrees grossly with observational inferences so far. For an isopedic magnetic field in a gas disc, the ratio f between the DM and baryon potentials depends strongly on the magnetic field strength. Therefore, a massive DM halo is needed to counteract either the strong stellar velocity dispersion and rotation of the stellar disc or the magnetic Lorentz force in the gas disc. By the radial force balances, the DM halo mass increases for faster disc rotation.
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