We present a measurement of the rate of Type Ia supernovae (SNe Ia) from the first of three seasons of data from the SDSS-II Supernova Survey. For this measurement, we include 17 SNe Ia at redshift z ≤ 0.12. Assuming a flat cosmology with Ωm = 0.3 = 1 - ΩΛ, we find a volumetric SN Ia rate of [2:93-0.040 +0.17(systematic)-0.71+0.90(statistical) × 10-5 SNe Mpc-3 h703 yr -1, at a volume-weighted mean redshift of 0.09. This result is consistent with previous measurements of the SN Ia rate in a similar redshift range. The systematic errors are well controlled, resulting in the most precise measurement of the SN Ia rate in this redshift range. We use a maximum likelihood method to fit SN rate models to the SDSS-II Supernova Survey data in combination with other rate measurements, thereby constraining models for the redshift evolution of the SN Ia rate. Fitting the combined data to a simple power-law evolution of the volumetric SN Ia rate, rV ∝ (1 + z)β, we obtain a value of β = 1.5 ± 0.6, i.e., the SN Ia rate is determined to be an increasing function of redshift at the ∼-2.5 σ level. Fitting the results to a model in which the volumetric SN rate is rV = Aρ(t) + Bρ(t), where ρ(t) is the stellar mass density and ρ(t) is the star formation rate, we find A = (2.8 ± 1.2) × 10-14 SNe M⊙-1 yr -1, B = (9.3-3.1+3.4 × 10-4 SNe Mȯ-1.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science