The Supernova Legacy Survey: measurement of ΩM, ΩΛ and w from the first year data set
Sullivan, M.; Lidman, C.; Aldering, G.; Astier, P.; Fabbro, S.; Goobar, A.; Howell, D. A.; Pain, R.; Perlmutter, S.; Carlberg, R. G.; Aubourg, E.; Mourao, A.; Walton, N.; Ellis, R. S.; Basa, S.; Guy, J.; Palanque-Delabrouille, N.; Mouchet, M.; Rich, J.; Ripoche, P.; Tao, C.; Neill, J. D.; Arsenijevic, V.; Regnault, N.; Antilogus, P.; McMahon, R.; Hardin, D.; Balland, C.; Fouchez, D.; Hook, I. M.; Perrett, K.; Pritchet, C. J.; Balam, D.; Baumont, S.; Gonçalves, A. C.; Lafoux, H.; Taillet, R.; Bronder, J.; Courtois, H.; Filiol, M.; Guide, D.; Lusset, V.
France, Canada, Portugal, United Kingdom, United States, Chile, Sweden
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 z=1, 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: Ω_M= 0.263 ± 0.042 (stat) ± 0.032 (sys) for a flat ΛCDM model; and w = -1.023 ± 0.090 (stat) ± 0.054 (sys) 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.