A local void and the accelerating Universe

Abstract

Corresponding to the recent observational claims that we are in a local void (an underdense region) on scales of 200-300 Mpc, the magnitude-redshift relation in a cosmological model with a local void is investigated. It is already evident that the accelerating behaviour of high-z supernovae can be explained in this model, because the local void plays a role similar to the positive cosmological constant. In this paper the dependence of the behaviour on the gaps of cosmological parameters in the inner (low-density) region and the outer (high-density) region, the radius of the local void, and the dumpiness parameter is studied and its implications are discussed.