An Efficient Approach to Obtaining Large Numbers of Distant Supernova Host Galaxy Redshifts

TL;DR

This paper demonstrates an efficient method using the 2dF/AAOmega spectrograph on the AAT to obtain redshifts for a large number of supernova host galaxies, significantly increasing the available data for high-redshift supernova studies.

Contribution

The study introduces a practical approach to rapidly acquire redshifts for supernova host galaxies using wide-field fibre-fed spectrographs on 4m telescopes, enhancing high-redshift supernova research capabilities.

Findings

Redshifts obtained for 400 host galaxies in two SNLS fields.

Median redshift of host galaxies is 0.77, 25% higher than previous spectroscopic samples.

Method demonstrates efficiency for future large-area supernova surveys.

Abstract

We use the wide-field capabilities of the 2dF fibre positioner and the AAOmega spectrograph on the Anglo-Australian Telescope (AAT) to obtain redshifts of galaxies that hosted supernovae during the first three years of the Supernova Legacy Survey (SNLS). With exposure times ranging from 10 to 60 ksec per galaxy, we were able to obtain redshifts for 400 host galaxies in two SNLS fields, thereby substantially increasing the total number of SNLS supernovae with host galaxy redshifts. The median redshift of the galaxies in our sample that hosted photometrically classified Type Ia supernovae (SNe Ia) is 0.77, which is 25% higher than the median redshift of spectroscopically confirmed SNe Ia in the three-year sample of the SNLS. Our results demonstrate that one can use wide-field fibre-fed multi-object spectrographs on 4m telescopes to efficiently obtain redshifts for large numbers of supernova host galaxies over the large areas of sky that will be covered by future high-redshift supernova surveys, such as the Dark Energy Survey.