Strigari Louis E, Bullock James S, Kaplinghat Manoj, Simon Joshua D, Geha Marla, Willman Beth, Walker Matthew G
Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, California 92697-4574, USA.
Nature. 2008 Aug 28;454(7208):1096-7. doi: 10.1038/nature07222.
The Milky Way has at least twenty-three known satellite galaxies that shine with luminosities ranging from about a thousand to a billion times that of the Sun. Half of these galaxies were discovered in the past few years in the Sloan Digital Sky Survey, and they are among the least luminous galaxies in the known Universe. A determination of the mass of these galaxies provides a test of galaxy formation at the smallest scales and probes the nature of the dark matter that dominates the mass density of the Universe. Here we use new measurements of the velocities of the stars in these galaxies to show that they are consistent with them having a common mass of about 10(7) within their central 300 parsecs. This result demonstrates that the faintest of the Milky Way satellites are the most dark-matter-dominated galaxies known, and could be a hint of a new scale in galaxy formation or a characteristic scale for the clustering of dark matter.
银河系至少有二十三个已知的卫星星系，其光度范围约为太阳光度的一千倍至十亿倍。其中一半的星系是在过去几年的斯隆数字巡天中发现的，它们是已知宇宙中光度最低的星系之一。确定这些星系的质量可以检验最小尺度下的星系形成情况，并探究主导宇宙质量密度的暗物质的本质。在此，我们利用对这些星系中恒星速度的新测量结果表明，它们在中心300秒差距内的共同质量约为10⁷，这一结果是相符的。这一结果表明，银河系最暗的卫星星系是已知的暗物质主导程度最高的星系，可能暗示着星系形成中的一个新尺度，或者是暗物质聚集的一个特征尺度。
