/!\ 14h /!\ What is the evidence for cosmic acceleration? - Subir Sarkar

Monday 29 Feb 2016, 14:00 → 15:00 Europe/Paris

The ‘standard’ model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present — as was inferred from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these ‘standardisable candles’ indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion. I will discuss some interesting possibilities this raises and further observational tests.