Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom and Interdisciplinary Centre for Mathematical and Computational Modelling (ICM), University of Warsaw, ul. Pawińskiego 5a, Warsaw, Poland.
Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom and Institute for Particle Physics Phenomenology, Department of Physics, Durham University, Durham DH1 3LE, United Kingdom.
Phys Rev Lett. 2014 Jun 6;112(22):221102. doi: 10.1103/PhysRevLett.112.221102. Epub 2014 Jun 5.
The velocity field of dark matter and galaxies reflects the continued action of gravity throughout cosmic history. We show that the low-order moments of the pairwise velocity distribution v_{12} are a powerful diagnostic of the laws of gravity on cosmological scales. In particular, the projected line-of-sight galaxy pairwise velocity dispersion σ_{12}(r) is very sensitive to the presence of modified gravity. Using a set of high-resolution N-body simulations, we compute the pairwise velocity distribution and its projected line-of-sight dispersion for a class of modified gravity theories: the chameleon f(R) gravity and Galileon gravity (cubic and quartic). The velocities of dark matter halos with a wide range of masses would exhibit deviations from general relativity at the (5-10)σ level. We examine strategies for detecting these deviations in galaxy redshift and peculiar velocity surveys. If detected, this signature would be a "smoking gun" for modified gravity.
暗物质和星系的速度场反映了引力在整个宇宙历史中的持续作用。我们表明，成对速度分布 v_{12} 的低阶矩是宇宙学尺度上引力定律的强大诊断工具。特别是，视线星系对速度弥散 σ_{12}(r) 对修改后的引力非常敏感。使用一组高分辨率 N-体模拟，我们为一类修改后的重力理论计算了成对的速度分布及其视线的分散度：变色龙 f(R)重力和 Galileon 重力（立方和四次）。具有广泛质量范围的暗物质晕的速度将在（5-10）σ 水平上偏离广义相对论。我们研究了在星系红移和特殊速度测量中检测这些偏差的策略。如果检测到，这一特征将是修改后的重力的“确凿证据”。
