A Type II Supernova Hubble diagram from the CSP-I, SDSS-II, and SNLS surveys

TL;DR

This paper constructs a Type II supernova Hubble diagram using photometric data from multiple surveys, demonstrating its potential for cosmology with upcoming large-scale surveys despite current limitations.

Contribution

It develops a photometric method to use Type II supernovae for cosmology, expanding the tools available for distance measurements without spectral data.

Findings

Achieved an intrinsic dispersion of 0.35 mag with the PCM.

Derived a cosmological matter density of Ω_m=0.32^{+0.30}_{-0.21}.

Provided independent evidence for dark energy at two sigma.

Abstract

The coming era of large photometric wide-field surveys will increase the detection rate of supernovae by orders of magnitude. Such numbers will restrict spectroscopic follow-up in the vast majority of cases, and hence new methods based solely on photometric data must be developed. Here, we construct a complete Hubble diagram of Type II supernovae combining data from three different samples: the Carnegie Supernova Project-I, the Sloan Digital Sky Survey-II SN, and the Supernova Legacy Survey. Applying the Photometric Colour Method (PCM) to 73 Type II supernovae (SNe~II) with a redshift range of 0.01--0.5 and with no spectral information, we derive an intrinsic dispersion of 0.35 mag. A comparison with the Standard Candle Method (SCM) using 61 SNe~II is also performed and an intrinsic dispersion in the Hubble diagram of 0.27 mag is derived, i.e., 13\% in distance uncertainties. Due to the lack of good statistics at higher redshifts for both methods, only weak constraints on the cosmological parameters are obtained. However, assuming a flat Universe and using the PCM, we derive a Universe's matter density: $\Omega_{m}$=0.32$^{+0.30}_{-0.21}$ providing a new independent evidence for dark energy at the level of two sigma.