暗能量修正引力理论中的非线性增长
Nonlinear growth in modified gravity theories of dark energy
摘要：
结构增长的理论差异提供了一种可能性，即我们可以区分暗能量的修正引力理论和\LambdaCDM。应用当前和未来的大尺度星系和弱透镜调查这个问题的一个重大障碍是，虽然轻度非线性制度是重要的，但在修正的引力理论中缺乏非线性增长的数值模拟。一个主要的问题是，现有的分析拟合，使用模拟标准重力，可以放心地应用。在本文中，我们解决了这个问题，展示了重力改变的各种模型（包括Dvali、Gabadadze和Porrati模型）的N体模拟结果。我们考虑修改，改变泊松方程，也考虑存在的各向异性剪切应力，改变粒子如何响应重力电势梯度。我们建立如何以及分析适合的物质功率谱的孔雀和Dodds和史密斯等人。能够预测的非线性增长中发现的模拟从z=50到今天，也考虑了弱透镜收敛功率谱的影响。我们发现，分析拟合提供了良好的协议与模拟，在1σ的模拟结果的情况下，各向异性应力和尺度相关的和独立的修改的泊松方程。没有强烈的偏好，无论是分析拟合被发现。
英文摘要：
Theoretical differences in the growth of structure offer the possibility that we might distinguish between modified gravity theories of dark energy and \LambdaCDM. A significant impediment to applying current and prospective large scale galaxy and weak lensing surveys to this problem is that, while the mildly nonlinear regime is important, there is a lack of numerical simulations of nonlinear growth in modified gravity theories. A major question exists as to whether existing analytical fits, created using simulations of standard gravity, can be confidently applied. In this paper we address this, presenting results of N-body simulations of a variety of models where gravity is altered including the Dvali, Gabadadze and Porrati model. We consider modifications that alter the Poisson equation and also consider the presence of anisotropic shear stress that alters how particles respond to the gravitational potential gradient. We establish how well analytical fits of the matter power spectrum by Peacock and Dodds and Smith et al. are able to predict the nonlinear growth found in the simulations from z=50 up to today, and also consider implications for the weak lensing convergence power spectrum. We find that the analytical fits provide good agreement with the simulations, being within 1σof the simulation results for cases with and without anisotropic stress and for scale-dependent and independent modifications of the Poisson equation. No strong preference for either analytical fit is found.
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