http://arxiv.org/abs/1508.05544
The $m$-$z$ relation for Type Ia supernovae is compatible with the cosmological concordance model if one assumes that the Universe is homogeneous, at least with respect to light propagation. This could be due to the density along each line of sight being equal to the overall cosmological density, or to `safety in numbers’, with variation in the density along all lines of sight averaging out if the sample is large enough. Statistical correlations (or lack thereof) between redshifts, residuals (differences between the observed distance moduli and those calculated from the best-fitting cosmological model), and observational uncertainties suggest that the former scenario is the better description, so that one can use the traditional formula for the luminosity distance safely without worry.
P. Helbig
Tue, 25 Aug 15
67/69
Comments: 5 pages, 6 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society (includes small changes made while checking the proofs). Related information available at this http URL