The supernova rate in local galaxy clusters

TL;DR

This paper measures supernova rates in galaxy clusters, finding higher Type Ia rates in early-type cluster galaxies compared to the field, and reports the first core-collapse SN rate in cluster late-type galaxies, suggesting environmental effects influence SN occurrence.

Contribution

It provides the first measurement of core-collapse supernova rates in cluster late-type galaxies and compares these rates with field galaxies, highlighting environmental influences on supernova rates.

Findings

Type Ia SN rate in cluster early-type galaxies is 3 times higher than in field galaxies.

Cluster membership, morphology, and radio power affect SN rates.

Core-collapse SN rate in cluster late-type galaxies is similar to that in field galaxies.

Abstract

We report a measurement of the supernova (SN) rates (Ia and core-collapse) in galaxy clusters based on the 136 SNe of the sample described in Cappellaro et al. (1999) and Mannucci et al. (2005). Early-type cluster galaxies show a type Ia SN rate (0.066 SNuM) similar to that obtained by Sharon et al. (2007) and more than 3 times larger than that in field early-type galaxies (0.019 SNuM). This difference has a 98% statistical confidence level. We examine many possible observational biases which could affect the rate determination, and conclude that none of them is likely to significantly alter the results. We investigate how the rate is related to several properties of the parent galaxies, and find that cluster membership, morphology and radio power all affect the SN rate, while galaxy mass has no measurable effect. The increased rate may be due to galaxy interactions in clusters, inducing either the formation of young stars or a different evolution of the progenitor binary systems. We present the first measurement of the core-collapse SN rate in cluster late-type galaxies, which turns out to be comparable to the rate in field galaxies. This suggests that no large systematic difference in the initial mass function exists between the two environments.