Analyses of Type Ia Supernova Data in Cosmological Models with a Local Void

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, H I 0, (2) the best-fit outer density parameter, ΩII0, and cosmological constant parameter, λ II 0, are, respectively, increasing and decreasing functions of R, and (3) (ΩII0, λ II 0) 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. In present day cosmology, the most important observations are those of the [mag-nitudem- redshift z] relation for type Ia supernovae (SNIa) and the CMB anisotropy. In the former observations, SNIa play the role of the best standard candles, and tw