Probing the anisotropic local universe and beyond with SNe Ia data
  The question of the transition to global isotropy from our anisotropic local
Universe is studied using the Union 2 catalogue of Type Ia supernovae (SNe Ia).
We construct a "residual" statistic sensitive to systematic shifts in their
brightness in different directions and use this to search in different redshift
bins for a preferred direction on the sky in which the SNe Ia are brighter or
fainter relative to the 'standard' LCDM cosmology. At low redshift (z<0.05) we
find that an isotropic model such as LCDM is barely consistent with the SNe Ia
data at 2-3 sigma. A complementary maximum likelihood analysis of peculiar
velocities confirms this finding -- there is a bulk flow of around 260 km/sec
at z \sim 0.06, which disagrees with LCDM at 1-2 sigma. Since the Shapley
concentration is believed to be largely responsible for this bulk flow, we make
a detailed study of the infall region: the SNe Ia falling away from the Local
Group towards Shapley are indeed significantly dimmer than those falling
towards us and on to Shapley. Convergence to the CMB rest frame must occur well
beyond Shapley (z>0.06) so the low redshift bulk flow can systematically bias
any reconstruction of the expansion history of the Universe. At high redshifts
z>0.15 the agreement between the SNe Ia data and the isotropic LCDM model does
improve, however, the sparseness and low quality of the data means that LCDM
cannot be singled out as the preferred cosmological model.
