Revised Supernova Rates from the IfA Deep Survey

TL;DR

This paper re-evaluates supernova rates from the IfA Deep survey using improved photometric techniques, finding a lower rate at z~0.5 and a steadily increasing rate up to z=1.05, aligning better with other surveys.

Contribution

It introduces an improved photometric analysis method that revises supernova rates, resolving previous discrepancies and extending measurements to higher redshifts.

Findings

Revised supernova rate at z~0.5 is lower than previous estimates.

Supernova rate increases steadily with redshift up to z=1.05.

No evidence of a peak in supernova rate within the studied redshift range.

Abstract

The IfA Deep survey uncovered ~130 thermonuclear supernovae (TNSNe, i.e. Type Ia) candidates at redshifts from z=0.1 out to beyond z=1. The TNSN explosion rates derived from these data have been controversial, conflicting with evidence emerging from other surveys. This work revisits the IfA Deep survey to re-evaluate the photometric evidence. Applying the SOFT program to the light curves of all SN candidates, we derive new classification grades and redshift estimates. We find a volumetric rate for z~0.5 that is substantially smaller than the originally published values, bringing the revised IfA Deep rate into good agreement with other surveys. With our improved photometric analysis techniques, we are able to confidently extend the rate measurements to higher redshifts, and we find a steadily increasing TNSN rate, with no indication of a peak out to z=1.05.