星系中的暗物质.pdf

Dark Matter in Galaxies 星系中的暗物质 Ken Freeman Research School of Astronomy Astrophysics, ANU 澳大利亚国立大学天文学教授 弗里曼 1 Beijing Planetarium 北京天文馆 July 2010 The Milky Way as seen from the sun 从太阳系看银河系 NGC 4565: an edge-on spiral 侧面朝向我们的漩涡星系 (see the flat rotating disk and the central bulge) （注意它旋转的盘和中心的核球） 2 There is a very important component that cannot be seen at all 星系中还有一个非常重要的部分，我们根本看不见 How do we know it is there ? the dark halo 我们怎么知道它的存在呢？ 暗物质晕 Almost all galaxies have a dark halo we see its gravitational effect on their rotation curves ... For example 几乎所有的星系都有个暗物质晕… 通过星系的旋转曲线可以知道其引力效应… Rotation at large radii is much faster than can be understood from the gravitational field of the stars and gas alone. 大半径尺度上的旋转速度比 仅通过恒星和气体的引力场 所得出的旋转速度要快 3 For sta