The Production Rate of SN Ia Events in Globular Clusters

TL;DR

This study investigates whether globular clusters significantly contribute to Type Ia supernovae in early-type galaxies, finding that their contribution is likely minimal based on archival HST data analysis.

Contribution

The paper provides the first observational upper limits on the rate of SN Ia production in globular clusters, challenging previous assumptions of high enhancement rates.

Findings

No definitive globular cluster counterparts for SNe Ia in examined galaxies.

Upper limit of 42 times the field rate for SN Ia production in globular clusters.

Globular clusters are unlikely to account for a significant fraction of SNe Ia in early-type galaxies.

Abstract

In globular clusters, dynamical evolution produces luminous X-ray emitting binaries at a rate about 200 times greater than in the field. If globular clusters also produce SNe Ia at a high rate, it would account for much of the SN Ia events in early type galaxies and provide insight into their formation. Here we use archival HST images of nearby galaxies that have hosted SNe Ia to examine the rate at which globular clusters produce these events. The location of the SN Ia is registered on an HST image obtained before the event or after the supernova faded. Of the 36 nearby galaxies examined, 21 had sufficiently good data to search for globular cluster hosts. None of the 21 supernovae have a definite globular cluster counterpart, although there are some ambiguous cases. This places an upper limit to the enhancement rate of SN Ia production in globular clusters of about 42 at the 95% confidence level, which is an order of magnitude lower than the enhancement rate for luminous X-ray binaries. Even if all of the ambiguous cases are considered as having a globular cluster counterpart, the upper bound for the enhancement rate is 82 at the 95% confidence level, excluding an enhancement rate of 200. Barring unforeseen selection effects, we conclude that globular clusters are not responsible for producing a significant fraction of the SN Ia events in early-type galaxies.