Probing gravity with redshift surveys

怀特博士将通过一系列大型、高精度的n体模拟来使用分析模型，以更好地理解暗能量和宇宙结构的增长。当从它们的红移来估计它们的距离时，大尺度上的星系在视线方向上比在切向上更强烈地聚集在一起。这种“红移扭曲”既取决于星系之间的引力吸引，也取决于暗能量在加速宇宙膨胀中的作用。在广义相对论中，红移畸变与弱引力透镜依赖于相同的宇宙学参数组合，但在其他理论中，这两种依赖关系有所不同。怀特博士将使用不同的基本引力理论来运行宇宙n体模拟，然后“观察”这些，以探索如何最好地利用红移扭曲来测试广义相对论的替代方案。他和他的团队还将发展一种微扰理论，以跟踪星系群集进入轻度非线性状态，在那里速度扰动不再严格地与密度波动成比例。该项目将解决观测解释、红移空间扭曲建模以及星系和暗物质之间的联系等突出问题。研究生将通过参与研究得到训练。广义相对论的检验在物理学和天文学中有着广泛的意义。怀特博士将继续他关于宇宙学的公开演讲和流行文章，并在公共网站上提供教育信息。

Dr White will use analytical modeling, informed by a series of large, high precision N-body simulations, to better understand dark energy and the growth of structure in the cosmos. When their distances are estimated from their redshifts, galaxies on large scales appear to be more strongly clumped along the line of sight than in the tangential direction. This 'redshift distortion' depends on both the gravitational attraction between the galaxies and the effect of dark energy in accelerating the cosmic expansion. In General Relativity, the redshift distortion depends on the same combination of cosmological parameters as does weak gravitational lensing, but in other theories the two dependences differ. Dr White will use different underlying theories of gravity to run cosmological N-body simulations, then 'observe' these, to explore how redshift distortions can best be used in testing alternatives to General Relativity. He and his team will also develop a perturbation theory to follow galaxy clustering into a mildly nonlinear regime, where the velocity perturbations are no longer strictly proportional to the density fluctuations. The project will address outstanding issues in the interpretation of surveys, the modeling of redshift space distortions, and the connection between galaxies and dark matter.A graduate student will be trained through participating in the research. Tests of General Relativity have broad implications throughout physics and astronomy. Dr White will continue his public outreach talks and popular articles on cosmology, and supply educational information on public web sites.