We present a detailed analysis (including redshift tomography) of the cosmic
dipoles in the Keck+VLT quasar absorber and in the Union2 SnIa samples. We show
that the fine structure constant cosmic dipole obtained through the Keck+VLT
quasar absorber sample at 4.1σ level is anomalously aligned with the
corresponding dark energy dipole obtained through the Union2 sample at
2σ level. The angular separation between the two dipole directions is
11.3∘±11.8∘. We use Monte Carlo simulations to find the
probability of obtaining the observed dipole magnitudes with the observed
alignment, in the context of an isotropic cosmological model with no
correlation between dark energy and fine structure constant α. We find
that this probability is less than one part in 106. We propose a simple
physical model (extended topological quintessence) which naturally predicts a
spherical inhomogeneous distribution for both dark energy density and fine
structure constant values. The model is based on the existence of a recently
formed giant global monopole with Hubble scale core which also couples
non-minimally to electromagnetism. Aligned dipole anisotropies would naturally
emerge for an off-centre observer for both the fine structure constant and for
dark energy density. This model smoothly reduces to \lcdm for proper limits of
its parameters. Two predictions of this model are (a) a correlation between the
existence of strong cosmic electromagnetic fields and the value of α and
(b) the existence of a dark flow on Hubble scales due to the repulsive gravity
of the global defect core (`Great Repulser') aligned with the dark energy and
α dipoles. The direction of the dark flow is predicted to be towards the
spatial region of lower accelerating expansion. Existing data about the dark
flow are consistent with this prediction.Comment: 14 pages 11 figures (two column revtex). Aceepted in Phys. Rev. D (to
appear). Significant extensions (mostly on section 4 on the theoretical
model), added references, corrected typos. The data, updated mathematica and
C program files used for the numerical analysis may be downloaded from
http://leandros.physics.uoi.gr/defsdipole