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Astronomy and Astrophysics 447 (2006) 31-48
The Supernova Legacy Survey: Measurement of $\Omega_M$, $\Omega_\Lambda$ and w from the First Year Data Set
P. Astier1, J. Guy1, N. Regnault1, R. Pain1, E. Aubourg2, 3, D. Balam, S. Basa4, R.G. Carlberg, S. Fabbro, D. Fouchez4, I.M. Hook, D.A. Howell, H. Lafoux, J.D. Neill, N. Palanque-Delabrouille, K. Perrett, C.J. Pritchet, J. Rich, M. Sullivan, Richard Taillet1, G. Aldering, P. Antilogus1, V. Arsenijevic, C. Balland1, 2, S. Baumont, J. Bronder, Hélène M. Courtois, R.S. Ellis, M. Filiol5, A.C. Goncalves, A. Goobar, D. Guide1, D. Hardin1, V. Lusset, C. Lidman, R. Mcmahon, M. Mouchet2, 6, A. Mourao, S. Perlmutter, P. Ripoche4, C. Tao4, N. Walton
SNLS Collaboration(s)

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. 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 : Omega_M = 0.263 +/- 0.042(stat) +/- 0.032(sys) for a flat LambdaCDM 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.
1 :  LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
2 :  APC - UMR 7164 - AstroParticule et Cosmologie
3 :  DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
4 :  CPPM - Centre de Physique des Particules de Marseille
5 :  LAM - Laboratoire d'Astrophysique de Marseille
6 :  LUTH - Laboratoire Univers et Théories
Physique/Astrophysique/Cosmologie et astrophysique extra-galactique

Planète et Univers/Astrophysique
supernovae: general – cosmology: observations
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