Astronomy & Astrophysics Seminar: Digging for Treasure: supernovae in SDSS spectra explain the rate-mass relation

Abstract:

Based on a sample of nearby supernovae discovered in the Lick Observatory Supernova Search (LOSS), Li et al. (2011b) found that galaxies with higher stellar masses hosted lower supernova rates per unit mass ("specific rates") for all types of supernovae. Using a code that detects and classifies supernovae in galaxy spectra, we have discovered a sample of ~135 Type Ia and II supernovae, which we use to measure specific supernova rates as a function of galaxy stellar mass, as well as star-formation rate (SFR) and specific SFR. We show that the so-called "rate-mass relation" for Type Ia and Type II supernovae can be explained as a combination of the delay-time distribution (DTD) for each type of supernova and galaxy downsizing (i.e., massive galaxies tend to be older than less massive ones). This model accounts for the correlations between the specific supernova rates and galaxy SFR and specific SFR, as well. I will also describe preliminary results from a re-analysis of the LOSS rates, which extends our work to stripped-envelope core-collapse supernovae (i.e., Tyeps Ib/c).

Seminar Organizer: Prof. Rennan Barkana