Spectroscopic Determination of the Low Redshift Type Ia Supernova Rate from the Sloan Digital Sky Survey

Supernova rates (SNRs) are directly coupled to high-mass stellar birth and evolution. As such, they are one of the few direct measures of the history of cosmic stellar evolution. In this paper, we describe a probabilistic technique for identifying supernovae within spectroscopic samples of galaxies. We present a study of 52 Type Ia supernovae ranging in age from –14 days to +40 days extracted from a parent sample of ~350,000 spectra from the SDSS DR5. We find an SNR of 0.472+0.048 –0.039(Systematic)+0.081 –0.071(Statistical)SNu at a redshift of z = 0.1. This value is higher than other values at low redshift at the 1σ level, but is consistent at the 3σ level. In this paper, we demonstrate the potential for the described approach to detect supernovae in future spectroscopic surveys.