The Supernova Legacy Survey: measurement of $\Omega_{\mathsf{M}}$, $\Omega_\mathsf{\Lambda}$ and<i>w</i>from the first year data set

TLDR

The study presents distance measurements to 71 high‑redshift Type Ia supernovae from the first year of the 5‑year Supernova Legacy Survey. The supernovae were detected and photometrically monitored with CFHT’s MegaPrime/MegaCam across four one‑square‑degree fields, followed by spectroscopic confirmation at VLT, Gemini, and Keck, and systematic uncertainties were assessed using the multi‑band CFHT photometry. Cosmological fits to the Hubble diagram provide constraints on Ω_M, Ω_Λ, and w, consistent with a flat ΛCDM model and refined by combining with SDSS BAO measurements.

Abstract

We present distance measurements to 71 high redshift type Ia supernovae discovered during the first year of the 5-year Supernova Legacy Survey (SNLS). These events were detected and their multi-color light-curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging four one-square degree fields in four bands, as part of the CFHT Legacy Survey (CFHTLS). Follow-up spectroscopy was performed at the VLT, Gemini and Keck telescopes to confirm the nature of the supernovae and to measure their redshift. With this data set, we have built a Hubble diagram extending to , with all distance measurements involving at least two bands. Systematic uncertainties are evaluated making use of the multi-band photometry obtained at CFHT. Cosmological fits to this first year SNLS Hubble diagram give the following results: for a flat ΛCDM model; and for a flat cosmology with constant equation of state w when combined with the constraint from the recent Sloan Digital Sky Survey measurement of baryon acoustic oscillations.