Supernova host galaxies in the dark energy survey: I. Deep coadds, photometry, and stellar masses

Abstract

The 5-yr Dark Energy Survey Supernova Programme (DES-SN) is one of the largest and deepest transient surveys to date in terms of volume and number of supernovae. Identifying and characterizing the host galaxies of transients plays a key role in their classification, the study of their formation mechanisms, and the cosmological analyses. To derive accurate host galaxy properties, we create depth-optimized coadds using single-epoch DES-SN images that are selected based on sky and atmospheric conditions. For each of the five DES-SN seasons, a separate coadd is made from the other four seasons such that each SN has a corresponding deep coadd with no contaminating SN emission. The coadds reach limiting magnitudes of order ∼27 in g band, and have a much smaller magnitude uncertainty than the previous DES-SN host templates, particularly for faint objects. We present the resulting multiband photometry of host galaxies for samples of spectroscopically confirmed type Ia (SNe Ia), core-collapse (CCSNe), and superluminous (SLSNe) as well as rapidly evolving transients (RETs) discovered by DES-SN. We derive host galaxy stellar masses and probabilistically compare stellar-mass distributions to samples from other surveys. We find that the DES spectroscopically confirmed sample of SNe Ia selects preferentially fewer high-mass hosts at high-redshift compared to other surveys, while at low redshift the distributions are consistent. DES CCSNe and SLSNe hosts are similar to other samples, while RET hosts are unlike the hosts of any other transients, although these differences have not been disentangled from selection effects.

Core-collapse, superluminous, and gamma-ray burst supernova host galaxy populations at low redshift: the importance of dwarf and starbursting galaxies

“…Similarly, small but statistically significant differences are also seen in other parameters (SFR, sSFR, and sequence offset). We find the median stellar mass 9.5(0.1) is slightly higher in comparison to the Dark Energy Survey CCSN sample of 47 objects (9.4) (Wiseman et al 2020), but still within the uncertainties of the measurements.…”

The Pantheon+ Analysis: Improving the Redshifts and Peculiar Velocities of Type Ia Supernovae Used in Cosmological Analyses

“…When host galaxies lack redshifts it is usually because they are faint and/or lowmass, and SNe Ia properties are correlated with their hosts' properties (e.g. Sullivan et al 2006;Smith et al 2020b;Wiseman et al 2020). Therefore the SN-z sample could represent a physically different subset of SNe that is not accounted for in, e.g.…”

The effect of environment on Type Ia supernovae in the Dark Energy Survey three-year cosmological sample

“…In this paper we use data from the Dark Energy Survey (DES; Dark Energy Survey Collaboration 2016) first threeyear cosmological sample (DES3YR; Brout et al 2019b) to measure the correlation between SN Ia luminosity and local environment. We combine this sample with photometry based on deep stacks of optical data free from SN light (Wiseman et al 2020, hereafter W20), we measure the local stellar mass and colour for each SN Ia in a range of physical aperture sizes. This dataset spans a wide redshift range (0.02 < z < 0.8) with SN candidates identified and spectroscopically targeted using algorithms principally agnostic to local environment (Kessler et al 2015;D'Andrea et al 2018).…”