Title: On cosmologically designed modified gravity theories Show Chinese title

Title: 关于宇宙学设计的修改引力理论

Abstract: Versions of parameterized pseudo-Newtonian gravity theories specially designed for cosmology have been introduced in recent cosmology literature. The modifications demand a zero-pressure fluid in the context of versions of modified Poisson-like equation with two different gravitational potentials. We consider such modifications in the context of relativistic gravity theories where the action is a general algebraic function of the scalar curvature, the scalar field, and the kinetic term of the field. In general it is not possible to isolate the zero-pressure fluid component simultaneously demanding a modification in the Poisson-like equation. Only in the small-scale limit we can realize some special forms of the attempted modifications. We address some loopholes in the possibility of showing non-Einstein gravity nature based on pseudo-Newtonian modifications in the cosmological context. We point out that future observations of gravitational weak lensing together with velocity perturbation can potentially test the validity of Einstein's gravity in cosmology context. Show Chinese abstract

Abstract: 针对宇宙学特别设计的参数化伪牛顿引力理论已在最近的宇宙学文献中被引入。 这些修改在具有两个不同引力势的修改型泊松方程背景下要求存在零压流体。 我们考虑在相对论引力理论背景下这样的修改，其中作用量是标量曲率、标量场以及场的动能项的一般代数函数。 一般来说，无法同时隔离零压流体成分并要求在泊松方程中的修改。 只有在小尺度极限下，我们才能实现一些尝试性修改的特殊形式。 我们指出了在基于宇宙学背景下伪牛顿修改来展示非爱因斯坦引力性质的可能性中存在的一些漏洞。 我们指出，未来对引力弱透镜和速度扰动的观测可能潜在地检验爱因斯坦引力在宇宙学背景下的有效性。