Linking galaxies with their dark matter halos

我们知道星系生活在延伸的暗物质晕中，但这些晕的大小和形状很少受到限制。暗物质不发光，这使得研究它的性质变得特别困难。然而，暗物质的数量和分布可以通过引力透镜效应来推断。将观测到的星系与它们所处的光晕联系起来，可以帮助我们约束星系形成的不同方面，例如恒星形成的效率。这个提议的重点是在两个不同的质量尺度上测量引力透镜，从而测量暗物质的性质。第一项研究涉及确定星系大小物体的暗物质特性，并将暗物质特性与观测到的星系发光特性联系起来。第二项研究与星系群有关。星系群是被引力束缚的小星系集合。局部宇宙中的大多数星系都生活在星系群中，但与星系团和单个星系相比，它们的性质相对来说知之甚少，因为它们很难在天空中识别。我建议使用地面和天基光学成像，结合不同波长的互补数据来研究这些系统，以便更好地了解星系和星系群的暗成分和亮成分之间的关系。

We know that galaxies live in extended dark matter halos, but the size and shape of these halos are poorly constrained. Dark matter does not emit light which makes studying its properties particularly difficult. However, the amount and distribution of dark matter can be inferred by its gravitational influence using gravitational lensing. Linking observed galaxies to the halos in which they live can help us to constrain different aspects of galaxy formation, for example the efficiency of star formation.This proposal focusses on measuring the gravitational lensing, hence dark matter properties, at two different mass scales. The first study concerns determining the dark matter properties of galaxy-sized objects, and correlating the dark matter properties with the observed, luminous properties of the galaxies. The second study is related to galaxy groups. Galaxy groups are small collections of galaxies which are gravitationally bound. Most galaxies in the local universe live in galaxy groups, but their properties are relatively poorly understood compared to galaxy clusters and individual galaxies, because they are difficult to identify on the sky. I propose to study these systems using ground- and space-based optical imaging, combined with complementary data at different wavelengths in order to better understand the relationship between the dark and luminous components of galaxies and galaxy groups.