Co-evolution of galaxies and their dark matter environment: constraining the standard structure formation paradigm through simulation and analysis of galaxy-galaxy lensing

星系的形成和演化主要是由它们所在的暗物质的引力效应驱动的。用与近星系相关的质量来观察遥远的星系，为探索星系与暗物质环境之间的关系提供了一种独特的方法。最近在测量这种星系-星系透镜(GGL)和最近的星系群透镜方面取得了很大进展，新一代广域成像相机将很快提供更好的测量结果。如果没有详细的数值模拟，这种观测的定量解释是不可能的。在小尺度上，GGL对单个星系的平均质量轮廓很敏感；在中尺度上，它探测星系的内容和星团晕的内部结构；在大尺度上，它约束星系和暗物质之间的统计关系。然而，暗物质分布的这些方面影响着所有尺度上的GGL信号，并与决定星系物理性质的演化过程密切相关，因此GGL观测的星系内容。我们正在使用一个非常大的N体模拟暗物质分布的演化(~1010个粒子的千年运行)，加上星系形成模型，可以在整个(500h−1 MPC)3体积内跟踪所有比SMC亮的星系的演化，以在当前的和谐宇宙中对GGL和星系群透镜进行详细的模拟。通过这个模拟追踪光线，我们可以模拟目前和即将到来的GGL观测，以了解关于星系形成和演化的各种假设。对我们模拟的星系+切变场天空图上的二阶和高阶自相关和互相关统计以及其他结构测量的研究将阐明它们的预期信噪比，它们与星系周围暗物质的三维分布的关系，以及它们对塑造星系可观测属性的演化过程的敏感性。如果当前和未来几代GGL观测要测试标准范式，限制其参数，或显示星系演化如何依赖于暗物质环境，这样的研究是必要的。

The formation and evolution of galaxies is driven primarily by the gravitational effects of the dark matter in which they are embedded. Lensing of distant galaxies by the mass associated with nearer systems offers a unique probe of the relation between galaxies and their dark matter environment. There has been much recent progress in measuring this galaxy-galaxy lensing (GGL) and more recently also galaxy-group lensing, and even better measurements will soon be provided by a new generation of wide-field imaging cameras. Quantitative interpretation of such observations is impossible without detailed numerical modeling. On small scales, GGL is sensitive to the mean mass profile of individual galaxies; on intermediate scales, it probes the galaxy content and internal structure of group and cluster halos; on large scales, it constrains the statistical relation between galaxies and dark matter. However, these aspects of the dark matter distribution affect the GGL signal on all scales and are intimately related to evolutionary processes which determine the physical properties of galaxies, hence the galaxy content of GGL surveys. We are employing a very large N-body simulation of the evolution of the dark matter distribution (the Millennium Run with ~ 1010 particles), together with galaxy formation modeling which can track the evolution of all galaxies brighter than the SMC throughout this (500h−1 Mpc)3 volume, to perform detailed simulations of GGL and galaxy-group lensing within the current concordance cosmology. By tracing light rays through this simulation we can mimic present and upcoming GGL surveys for a variety of assumptions about galaxy formation and evolution. A study of second- and higher-order auto- and cross-correlation statistics and other structure measures on our simulated galaxy + shear-field sky maps will clarify their expected signal-to-noise, their relation to the three-dimensional distribution of dark matter around galaxies, and their sensitivity to the evolutionary processes shaping the observable properties of galaxies. Such a study is required if current and future generations of GGL surveys are to test the standard paradigm, to constrain its parameters, or to show how galaxy evolution depends on dark matter environment.