The Volumetric Rate of Superluminous Supernovae at z~1

TL;DR

This paper measures the rate of superluminous supernovae at redshift ~1 using archival survey data, develops a photometric classification method, and explores their connection to gamma-ray bursts and host galaxy properties.

Contribution

It introduces a new photometric classification technique for SLSNe and provides the first rate measurement at z~1, linking SLSNe occurrence to cosmic star formation history.

Findings

SLSNe rate at z~1 is approximately 91 SNe per year per Gpc^3.

The SLSNe rate increases with redshift, mirroring cosmic star formation.

ULGRBs have a comparable rate to SLSNe, suggesting a possible connection.

Abstract

We present a measurement of the volumetric rate of superluminous supernovae (SLSNe) at z~1, measured using archival data from the first four years of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We develop a method for the photometric classification of SLSNe to construct our sample. Our sample includes two previously spectroscopically-identified objects, and a further new candidate selected using our classification technique. We use the point-source recovery efficiencies from Perrett et.al. (2010) and a Monte Carlo approach to calculate the rate based on our SLSN sample. We find that the three identified SLSNe from SNLS give a rate of 91 (+76/-36) SNe/Yr/Gpc^3 at a volume-weighted redshift of z=1.13. This is equivalent to 2.2 (+1.8/-0.9) x10^-4 of the volumetric core collapse supernova rate at the same redshift. When combined with other rate measurements from the literature, we show that the rate of SLSNe increases with redshift in a manner consistent with that of the cosmic star formation history. We also estimate the rate of ultra-long gamma ray bursts (ULGRBs) based on the events discovered by the Swift satellite, and show that it is comparable to the rate of SLSNe, providing further evidence of a possible connection between these two classes of events. We also examine the host galaxies of the SLSNe discovered in SNLS, and find them to be consistent with the stellar-mass distribution of other published samples of SLSNe.