Environment-derived constraints on the progenitors of low-luminosity type I supernovae

TL;DR

This study investigates the host galaxy environments of two types of low-luminosity supernovae, revealing that Ca-rich transients are linked to old stellar populations while SN2002cx-like events are associated with younger, star-forming regions.

Contribution

It provides new insights into the environmental constraints on the progenitors of low-luminosity supernovae, highlighting differences between Ca-rich and SN2002cx-like transients.

Findings

Ca-rich transients occur mainly in old stellar populations.

SN2002cx-like transients are associated with star-forming regions.

Different environments suggest distinct progenitor scenarios.

Abstract

We present a study of the properties of the host galaxies of unusual transient objects of two types, both being sub-luminous compared with the major classes of supernovae. Those of one type exhibit unusually strong calcium features, and have been termed 'Ca-rich'. Those of the second type, with SN2002cx as the prototype and SN2008ha as the most extreme example to date, have some properties in common with the first, but show typically lower ejecta velocities, and different early spectra. We confirm important differences in the environments of the two types, with the Ca-rich transients preferentially occurring in galaxies dominated by old stellar populations. Quantitatively, the association of the the Ca-rich transients with regions of ongoing star formation is well matched to that of type Ia supernovae. The SN2002cx-like transients are very different, with none of the present sample occurring in an early-type host, and a statistical association with star-formation regions similar to that of type II-P supernovae, and therefore a delay time of 30-50 Myrs.