The Supernova Legacy Survey 3-year sample: Type Ia supernovae photometric distances and cosmological constraints^⋆,⋆⋆

¹ LPNHE, CNRS/IN2P3, Université Pierre et Marie Curie Paris 6, Université Denis Diderot Paris 7, 4 place Jussieu, 75252 Paris Cedex 05, France
e-mail: guy@in2p3.fr
² Department of Physics (Astrophysics), University of Oxford, DWB, Keble Road, Oxford OX1 3RH, UK
³ Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309-0391, USA
⁴ Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto ON M5S 3H4, Canada
⁵ Université Paris 11, 91405 Orsay, France
⁶ LAM, CNRS, BP8, Traverse du Siphon, 13376 Marseille Cedex 12, France
⁷ CPPM, CNRS-IN2P3 and Université Aix-Marseille II, Case 907, 13288 Marseille Cedex 9, France
⁸ INAF – Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio (RM), Italy
⁹ Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117, USA
¹⁰ Department of Physics, University of California, Santa Barbara, Broida Hall, Mail Code 9530, Santa Barbara, CA 93106-9530, USA
¹¹ CEA, Centre de Saclay, Irfu/SPP, 91191 Gif-sur-Yvette, France
¹² Network Information Operations, DRDC-Ottawa, 3701 Carling Avenue, Ottawa, ON, K1A 0Z4, Canada
¹³ Department of Physics and Astronomy, University of Victoria, PO Box 3055 STN CSC, Victoria BC V8T 1M8, Canada
¹⁴ LPSC, CNRS-IN2P3, 53 rue des Martyrs, 38026 Grenoble Cedex, France
¹⁵ Department of Astrophysics, California Institute of Technology, MS 105-24, Pasadena, CA 91125, USA
¹⁶ CENTRA-Centro M. de Astrofisica and Department of Physics, IST, Lisbon, Portugal
¹⁷ LBNL, 1 Cyclotron Rd, Berkeley, CA 94720, USA
¹⁸ Anglo-Australian Observatory, PO Box 296, Epping, NSW 1710, Australia
¹⁹ Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy

Received: 19 March 2010
Accepted: 24 June 2010

Abstract

Aims. We present photometric properties and distance measurements of 252high redshift Type Ia supernovae (0.15 < z < 1.1) discovered during the first three years of the Supernova Legacy Survey (SNLS). These events were detected and their multi-colour 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 redshifts.

Methods. Systematic uncertainties arising from light curve modeling are studied, making use of two techniques to derive the peak magnitude, shape and colour of the supernovae, and taking advantage of a precise calibration of the SNLS fields.

Results. A flat ΛCDM cosmological fit to 231SNLS high redshift type Ia supernovae alone gives Ω_M = 0.211 ± 0.034(stat) ± 0.069(sys). The dominant systematic uncertainty comes from uncertainties in the photometric calibration. Systematic uncertainties from light curve fitters come next with a total contribution of  ± 0.026 on Ω_M. No clear evidence is found for a possible evolution of the slope (β) of the colour-luminosity relation with redshift.