Type II supernovae in low luminosity host galaxies

TL;DR

This study compares Type II supernovae in low-luminosity and brighter galaxies, revealing spectral and photometric differences linked to host galaxy metallicity, and providing insights into supernova properties and progenitor environments.

Contribution

It is the first comprehensive analysis of SN II spectral and photometric properties in low-luminosity hosts, highlighting metallicity effects on spectral features and light-curve behaviors.

Findings

SNe II in low-luminosity hosts show weaker Fe II lines.

They have slower light-curve declines.

No correlation between envelope mass or explosion energy with metallicity.

Abstract

We present an analysis of a new sample of type II core-collapse supernovae (SNe II) occurring within low-luminosity galaxies, comparing these with a sample of events in brighter hosts. Our analysis is performed comparing SN II spectral and photometric parameters and estimating the influence of metallicity (inferred from host luminosity differences) on SN II transient properties. We measure the SN absolute magnitude at maximum, the light-curve plateau duration, the optically thick duration, and the plateau decline rate in the V-band, together with expansion velocities and pseudo-equivalent-widths (pEWs) of several absorption lines in the SN spectra. For the SN host galaxies, we estimate the absolute magnitude and the stellar mass, a proxy for the metallicity of the host galaxy. SNe II exploding in low luminosity galaxies display weaker pEWs of Fe II $\lambda5018$, confirming the theoretical prediction that metal lines in SN II spectra should correlate with metallicity. We also find that SNe II in low-luminosity hosts have generally slower declining light curves and display weaker absorption lines. We find no relationship between the plateau duration or the expansion velocities with SN environment, suggesting that the hydrogen envelope mass and the explosion energy are not correlated with the metallicity of the host galaxy. This result supports recent predictions that mass-loss for red supergiants is independent of metallicity.