Analyses of type Ia supernova data in cosmological models with a local void

Abstract

The data for type Ia supernovae obtained by the High-z SN Search Team and Supernova Cosmology Project are analyzed using inhomogeneous cosmological models with a local void on scales of about 200 Mpc, to derive the best-fit values of model parameters and the confidence contours. The χ2 fitting is found to be slightly better than that in homogeneous models. It is shown that (1) the best-fit values are most sensitive to the ratio R of the outer Hubble constant, HII0, to the inner Hubble constant, HI0, (2) the best-fit outer density parameter, ΩII0, and cosmological constant parameter, λII0, are, respectively, increasing and decreasing functions of R, and (3) (ΩII0,λII0) can be (1, 0) for R ≈ 0.8. Moreover, it is shown that these models are naturally consistent with the new supernova data (SN1997ff) with z = 1.7.