The big bounce in rainbow universe

摘要

The usual Einstein’s equations is modified as a one parameter family of equations in the framework of rainbow gravity. In this Letter we derive the modified Friedmann–Robertson–Walker (FRW) equationswhen the cosmological evolution of radiation particles is taken into account. In particular, given some specific dispersion relations, the big bounce solutions to the modified FRW equations can be derived.Notably, to obtain a well defined rainbow metric at the moment of the big bounce, we find it seems necessary to introduce a cosmological constant which depends on the energy of probes as well, implyingthat a universe with a positive cosmological constant more likely undergoes a big bounce at least at this phenomenological level.