宇宙加速膨胀的一个玩具模型和修正的引力理论

Einstein引力理论在大尺度上的修正是解释目前宇宙加速膨胀的一类颇受关注的方案,它不需要引入奇怪的暗能量.作者构造了一个玩具模型,它与目前的天体物理数据相吻合,且能避免宇宙大撕裂.把宇宙标度因子a(t)代入由含待定修正项修正引力导出的宇宙动力学方程,并在t=t0处展开为Taylor级数,保留前2项,定出引力拉氏量中修正项的系数,从而把修正项置于更为可靠的基础上.

A Toy Model for Accelerated Expansion of the Universe and the Modified Gravity

The modification of Einstein gravity theory at large scale is a kind of attractive version of the accelerated expansion of the universe at present,without the assumption of mysterious "dark energy".A toy model which is compatible with the current astrophysical data and can avoid Big Rip of the universe is proposed.By substituting the scale factor of the universe,a(t),into the cosmic-dynamical equations derived from modified gravity with undetermined additional terms,then expanding the resultant equations into Taylor series with respect to t at t_0 and only taking the first two terms,the coefficient additional terms are determined.Thus,the additional modified terms are put on a more reliable basis.