A SN Ia Near a Globular Cluster in the Early-Type Galaxy NGC 5353

TL;DR

This study investigates the possible association of a Type Ia supernova with a globular cluster in NGC 5353, providing insights into progenitor origins and the environment's role in supernova occurrence.

Contribution

It presents the first detailed analysis of a SN Ia potentially linked to a globular cluster in an early-type galaxy, using HST imaging to refine positional data.

Findings

SN 2019ein is within 59 pc of a globular cluster candidate.

Chance alignment probability is about 3%, suggesting a possible association.

Progenitor scenarios include ejection from the cluster or long-term binary evolution.

Abstract

No progenitor of a Type Ia supernova is known, but in old population early-type galaxies, one may find SN Ia associated with globular clusters, yielding a population age and metallicity. It also provides insight into the formation path and the SN enhancement rate in globular clusters. We sought to find such associations and identified SN 2019ein to be within the ground-based optical positional uncertainty of a globular cluster candidate within the early-type galaxy NGC 5353 at about 30 Mpc distance. We reduced the positional uncertainties by obtaining Hubble Space Telescope images with the Advanced Camera for Surveys, using filters F475W and F814W and obtained in June 2020. We find that the globular cluster candidate has a magnitude, color, and angular extent that are consistent with it being a typical globular cluster. The separation between the globular cluster and SN 2019ein is 0.43'', or 59 pc in projection. The chance occurrence with a random globular cluster is about 3%, favoring but not proving an association. If the SN progenitor originated in the globular cluster, one scenario is that SN 2019ein was previously a double degenerate white dwarf binary that was dynamically ejected from the globular cluster and exploded within 10 Myr; models do not predict this to be common. Another, but less likely scenario is where the progenitor remained bound to the globular cluster, allowing the double degenerate binary to inspiral on a much longer timescale before producing a SN.