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

TL;DR

This paper introduces a probabilistic spectroscopic technique to identify Type Ia supernovae in galaxy spectra, measuring their rate at low redshift and demonstrating its potential for future surveys.

Contribution

A novel probabilistic method for detecting supernovae in spectroscopic data and applying it to measure the low-redshift Type Ia supernova rate.

Findings

Measured supernova rate of 0.472 SNu at z=0.1

Identified 52 supernovae from SDSS spectra, third largest sample to date

Demonstrated potential for future spectroscopic surveys

Abstract

Supernova rates 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 an 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 \simeq 50,000 spectra from the SDSS DR5. We find a Supernova Rate (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 1{\sigma}, but is consistent at the 3{\sigma} level. The 52 supernova candidates used in this study comprise the third largest sample of supernovae used in a type Ia rate determination to date. In this paper we demonstrate the potential for the described approach for detecting supernovae in future spectroscopic surveys.