Models of Universe with an inhomogeneous Big Bang singularity - II. CMBR dipole anisotropy as a byproduct of a conic Big-Bang singularity

The existence of stars and galaxies requires cosmological models with an inhomogeneous matter and radiation distribution. But in these models the initial singularity surface t(0)(r) is in general homogeneous (independent of r). In this second paper of a series devoted to an inhomogeneous Big Bang singularity, we investigate the cosmic microwave background radiation (CMBR) dipole. A special Tolman-Bondi Universe is used to study the effect of a Big-Bang singularity, depending linearly on r, on the CMBR anisotropy. It is shown that, for an observer located off the "center" of this Universe (r = 0), the parameters of the model can be tuned so as to reproduce, with a good approximation, the dipole and the quadrupole moments of the CMBR anisotropy observed in recent experiments. If the dipole should prove cosmological, a slight delaying of the Big-Bang over spatial coordinates would thus be a good candidate for its interpretation.