Dipole Anisotropies ofIRASGalaxies and the Contribution of a Large‐Scale Local Void

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Abstract
Recent observations of dipole anisotropies show that the velocity of the Local Group (vG) induced by the clustering of IRAS galaxies has an amplitude and direction similar to those of the velocity of the cosmic microwave background dipole anisotropy (vCMB), but the difference |vG - vCMB| is still ~170 km s-1, which is about 28% of |vCMB|. Here we consider the possibility that the origin of this difference comes from a hypothetical large-scale local void, with which we can account for the accelerating behavior of Type Ia supernovae 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 the Local Group and the center of the void must be 10-20 h-1 Mpc, whose accurate value depends on the background model parameters.

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