Five supernova survey galaxies in the southern hemisphere. II. The supernova rates

TL;DR

This study analyzes supernova rates in 3838 southern hemisphere galaxies, revealing dependencies on galaxy morphology, colors, and star formation activity, and providing insights into the origins of different supernova types.

Contribution

It offers the first comprehensive supernova rate analysis normalized to galaxy luminosities and stellar mass, highlighting the relationship with galaxy properties and star formation.

Findings

Core-collapse SN rates closely linked to star formation rate.

Type Ia SN rates suggest at least 15% originate from young stellar populations.

SN rates show no dependence on nuclear activity or environment.

Abstract

Based on the database compiled in the first article of this series, with 56 SN events discovered in 3838 galaxies of the southern hemisphere, we compute the rate of supernovae (SNe) of different types along the Hubble sequence normalized to the optical and near-infrared luminosities as well as to the stellar mass of the galaxies. We find that the rates of all SN types show a dependence on both morphology and colors of the galaxies, and therefore, on the star-formation activity. The rate of core-collapse (CC) SNe is confirmed to be closely related to the Star Formation Rate (SFR) and only indirectly to the total mass of the galaxies. The rate of SNe Ia can be explained by assuming that at least 15% of Ia events in spiral galaxies originates in relatively young stellar populations. We find that the rates show no modulation with nuclear activity or environment. The ratio of SN rates between types Ib/c and II shows no trend with spiral type.