Anisotropy of the Hubble Constant in a Cosmological Model with a Local Void on Scales of ~ 200 Mpc

Abstract

A spherical cosmological model with a local void on scales of $\sim 200$ Mpc and with an inhomogeneous Hubble constant was proposed in recent two papers. This model explains consistently the observed properties of the cosmic bulk flow, the accelerating behavior of type Ia supernovae and the CMB dipole anisotropy without invoking a cosmological constant. As we are in a position deviated from the center in the model, the anisotropy of the Hubble constant appears owing to the directional difference of the distance from the observer to the boundary of the void region. It is found that the anisotropy is maximally about 6% of the constant in the region of $200 \sim 500$ Mpc from us. This inhomogeneity and anisotropy of the Hubble constant are not so large as to be inconsistent with the present observation. The detection of this anisotropy in the future will be useful to clarify the implication of the inhomogeneity of the Hubble constant.