Core-collapse Supernovae in the Dark Energy Survey: Luminosity Functions and Host Galaxy Demographics

TL;DR

This study analyzes the luminosity functions and host galaxy properties of core-collapse supernovae from the Dark Energy Survey, comparing them with other surveys to understand differences in brightness and host galaxy characteristics across redshifts.

Contribution

It provides the first detailed luminosity functions and host galaxy demographics for DES CCSNe, highlighting differences with lower-redshift samples and exploring potential causes.

Findings

DES and ZTF SNe II are brighter than LOSS with high significance.

Host galaxies of DES SNe II are bluer than in ZTF despite similar stellar masses.

The cause of host galaxy colour differences remains uncertain.

Abstract

We present the luminosity functions and host galaxy properties of the Dark Energy Survey (DES) core-collapse supernova (CCSN) sample, consisting of 69 Type II and 50 Type Ibc spectroscopically and photometrically-confirmed supernovae over a redshift range $0.045<z<0.25$. We fit the observed DES $griz$ CCSN light-curves and K-correct to produce rest-frame $R$-band light curves. We compare the sample with lower-redshift CCSN samples from Zwicky Transient Facility (ZTF) and Lick Observatory Supernova Search (LOSS). Comparing luminosity functions, the DES and ZTF samples of SNe II are brighter than that of LOSS with significances of 3.0$\sigma$ and 2.5$\sigma$ respectively. While this difference could be caused by redshift evolution in the luminosity function, simpler explanations such as differing levels of host extinction remain a possibility. We find that the host galaxies of SNe II in DES are on average bluer than in ZTF, despite having consistent stellar mass distributions. We consider a number of possibilities to explain this -- including galaxy evolution with redshift, selection biases in either the DES or ZTF samples, and systematic differences due to the different photometric bands available -- but find that none can easily reconcile the differences in host colour between the two samples and thus its cause remains uncertain.