Dipole anisotropies of IRAS galaxies and the contribution of a large-scale local void

Recent observations of dipole anisotropies show that the velocity of the Local Group ($\Vec v_{\rm G}$) induced by clustering of IRAS galaxies has the amplitude and direction similar to those of the velocity of CMB dipole anisotropy ($\Vec v_{\rm CMB}$), but the difference $| \Vec v_{\rm G} - \Vec v_{\rm CMB} |$ remains to be $\sim 170$ km/s, which is about 28% of $|\Vec v_{\rm CMB} |$. Here we consider the possibility that the origin of this difference comes from a hypothetical large-scale local void, in which we can account for the accelerating behavior of SNIa due to the spatial inhomogeneity of the Hubble constant without dark energies, and derive the constraint to the model parameters of the local void. It is found as a result that the distance between he Local Group and the center of the void must be $(10 -- 20) h^{-1}$ Mpc, though it depends accurately on the background model parameters.