Ia supernovae data with no cosmic acceleration

The unexpected dimness of Type Ia supernovae at redshifts z . 1 has over the past 7 years been seen as an indication that the expansion of the universe is accelerating. A new model cosmology has been proposed by one of us (Wiltshire 2005), based on the idea that our observed universe resides in an underdense bubble remnant from a primordial epoch of cosmic inflation. Although there is no cosmic acceleration, it is claimed that the luminosity distance of type Ia supernovae data will nonetheless fit the new model, due to systematic effects. In this paper the hypothesis is tested statistically against the available type Ia supernovae data by both chi–square and Bayesian methods. The model gives good agreement if the density parameter, Ω0, is taken to be the density in ordinary baryonic matter only. If low Ω0 parameter values are accepted, then the model would dispense with both dark energy and non–baryonic dark matter, and an alternative explanation would be required for galaxy rotation curves and dynamical measurements of Ω0 on the scales of clusters of galaxies. Subject headings: luminosity distances, cosmology, inflation