Results of the Mount Stromlo Abell cluster supernova search

Abstract

We report the results of the Mount Stromlo Abell cluster supernova search, a three-year project to find supernovae (SNe) in a well-defined sample of high-density, southern Abell clusters with redshifts 0.02 ≥ z ≥ 0.08. The search discovered 48 SNe, 23 of which were consistent with SNe of type Ia (SNIa). Of these, 15 were spectroscopically classified SNIa, with the remaining 8 SNe tentatively classified as SNIa via the goodness of fit of the template light curves. This paper describes the methods employed to produce the light curves for the SNe discovered during the Mount Stromlo Abell cluster supernova search. We derive the redshift-independent distances to the SNIa from the search, as well as a large sample of other well-observed SNIa taken from the literature via a modified Δm15 template light curve fitting technique. This technique and the problems encountered in using it are described in detail. We construct a Hubble diagram for SNIa and show that our data with z < 0.2 are consistent with an accelerating universe. Using current Cepheid HST calibrations, we estimate that the value of the Hubble constant lies between 53 < H0 < 83 km-1 s-1 Mpc-1, with the large spread almost entirely due to possible systematic errors in the Cepheid calibration.