# SN1991bg-like supernovae are associated with old stellar populations

## TL;DR

This study links SN1991bg-like supernovae to old stellar populations, indicating their progenitors have long delay times over 6 billion years, unlike normal SNe Ia.

## Contribution

It provides direct observational evidence connecting 91bg-like supernovae to ancient stellar environments through integral field spectroscopy.

## Key findings

- Majority of host stellar populations show little recent star formation.
- Progenitors likely explode after delay times exceeding 6 Gyr.
- Distinct from normal SNe Ia with ~1 Gyr delay time.

## Abstract

SN1991bg-like supernovae are a distinct subclass of thermonuclear supernovae (SNe Ia). Their spectral and photometric peculiarities indicate their progenitors and explosion mechanism differ from `normal' SNe Ia. One method of determining information about supernova progenitors we cannot directly observe is to observe the stellar population adjacent to the apparent supernova explosion site to infer the distribution of stellar population ages and metallicities. We obtain integral field observations and analyse the spectra extracted from regions of projected radius $\sim\,\mathrm{kpc}$ about the apparent SN explosion site for 11 91bg-like SNe in both early- and late-type galaxies. We utilize full-spectrum spectral fitting to determine the ages and metallicities of the stellar population within the aperture. We find that the majority of the stellar populations that hosted 91bg-like supernovae have little recent star formation. The ages of the stellar populations suggest that that 91bg-like SN progenitors explode after delay times of $>6\,\mathrm{Gyr}$, much longer than the typical delay time of normal SNe Ia, which peaks at $\sim 1\,\mathrm{Gyr}$.