On the environments of type Ia supernovae within host galaxies

TL;DR

This study analyzes the environments of 102 Type Ia supernovae in star-forming galaxies, revealing their progenitors are not linked to recent star formation and are mainly relatively young, with environmental differences based on supernova color.

Contribution

It provides new insights into Type Ia supernova progenitors by analyzing their explosion site environments and their relation to star formation indicators.

Findings

SNe Ia show minimal association with H-alpha emission.

They do not trace near-UV emission, ruling out prompt progenitors.

Redder SNe Ia are more centrally located and associated with HII regions.

Abstract

We present constraints on supernovae type Ia (SNe~Ia) progenitors through an analysis of the environments found at the explosion sites of 102 events within star-forming host galaxies. H-alpha and GALEX near-UV images are used to trace on-going and recent star formation (SF), while broad band B, R, J, K imaging is also analysed. Using pixel statistics we find that SNe~Ia show the lowest degree of association with H-alpha emission of all supernova types. It is also found that they do not trace near-UV emission. As the latter traces SF on timescales less than 100 Myr, this rules out any extreme 'prompt' delay-times as the dominant progenitor channel of SNe~Ia. SNe~Ia best trace the B-band light distribution of their host galaxies. This implies that the population within star-forming galaxies is dominated by relatively young progenitors. Splitting SNe by their (B-V) colours at maximum light, 'redder' events show a higher degree of association to HII regions and are found more centrally within hosts. We discuss possible explanations of this result in terms of line of sight extinction and progenitor effects. No evidence for correlations between SN stretch and environment properties is observed.