Browsing by Subject "ia light curves"

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Improved Cosmological Constraints From A Joint Analysis Of The SDSS-II And SNLS Supernova Samples
(2014-08) Betoule, M.; Kessler, R.; Guy, J.; Mosher, J.; Hardin, D.; Biswas, R.; Astier, P.; El-Hage, P.; Konig, M.; Kuhlmann, S.; Marriner, J.; Pain, R.; Regnault, N.; Balland, C.; Bassett, B. A.; Brown, P. J.; Campbell, H.; Carlberg, R. G.; Cellier-Holzern, F.; Cinabro, D.; Conley, A.; D'Andrea, C. B.; DePoy, D. L.; Doi, M.; Ellis, R. S.; Fabbro, S.; Filippenko, A. V.; Foley, R. J.; Frieman, J. A.; Fouchez, D.; Galbany, L.; Goobar, A.; Gupta, R. R.; Hill, G. J.; Hlozek, R.; Hogan, C. J.; Hook, I. M.; Howell, D. A.; Jha, S. W.; Le Guillou, L.; Leloudas, G.; Lidrnan, C.; Marshall, J. L.; Moller, A.; Mourao, A. M.; Neveu, J.; Nichol, R.; Olmstead, M. D.; Palanque-Delabrouille, N.; Perlinutter, S.; Prieto, J. L.; Pritchet, C. J.; Richinond, M.; Riess, A. G.; Ruhlmann-Kleider, V.; Sako, M.; Sehahmaneche, K.; Schneider, D. P.; Smith, M.; Sollerman, J.; Sullivan, M.; Walton, N. A.; Wheeler, C. J.; Hill, G. J.
Aims. We present cosmological constraints from a joint analysis of type la supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The dataset includes several low-redshift samples (z < 0.1), all three seasons from the SDSS-11 (0.05 < z < 0.4), and three years from SNLS (0.2 < z < 1), and it totals 740 spectroscopically confirmed type la supernovae with high quality light curves. Methods. We followed the methods and assumptions of the SNLS three-year data analysis except for the following important improvements: I) the addition of the full SDSS-II spectroscopically-confirmed SN la sample in both the training of the SALT2 light-curve model and in the Hubble diagram analysis (374 SNe); 2) intercalibration of the SNLS and SDSS surveys and reduced systematic uncertainties in the photometric calibration, performed blindly with respect to the cosmology analysis; and 3) a thorough investigation of systematic errors associated with the SALT2 modeling of SN la light curves. Results. We produce recalibrated SN la light curves and associated distances for the SDSS-II and SNLS samples. The large SOSS-II sample provides an effective, independent, low -z anchor for the Hubble diagram and reduces the systematic error from calibration systematics in the low -z SN sample. For a flat ACDM cosmology, we find Omega(m), = 0.295 0.034 (stat+sys), a value consistent with the most recent cosmic microwave background (CMB) measurement from the Planck and WMAP experiments. Our result is 1.8 sigma (stat+sys) different than the previously published result of SNLS three-year data. The change is due primarily to improvements in the SNLS photometric calibration. When combined with CMB constraints, we measure a constant dark energy equation of state parameter omega = -1.018 +/- 0,057 (sral+sys) for a fiat universe. Adding baryon acoustic oscillation distance measurements gives similar constraints: omega = 59 -1.027 0.055. Our supernova measurements provide the most stringent constraints to date on the nature of dark energy.