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-Holzem, 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; Lidman, C; Marshall, J. L; Möller, A; Mourão, A. M; Neveu, J; Nichol, R; Olmstead, M. D; Palanque-Delabrouille, N; Perlmutter, S; Prieto, J. L; Pritchet, C. J; Richmond, M; Riess, A. G; Ruhlmann-Kleider, V; Sako, M; Schahmaneche, K; Schneider, D. P; Smith, M; Sollerman, J; Sullivan, M; Walton, N. A; Wheeler, C. J
Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples
Teil von
  • Astronomy and astrophysics (Berlin), 2014-08, Vol.568, p.A22
Ort / Verlag
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Aims. We present cosmological constraints from a joint analysis of type Ia 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-II (0.05 <z< 0.4), and three years from SNLS (0.2 <z< 1), and it totals 740 spectroscopically confirmed type Ia 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: 1) the addition of the full SDSS-II spectroscopically-confirmed SN Ia 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 Ia light curves. Results. We produce recalibrated SN Ia light curves and associated distances for the SDSS-II and SNLS samples. The large SDSS-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 ΛCDM cosmology, we find Ωm =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 1.8σ (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 w =−1.018 ± 0.057 (stat+sys) for a flat universe. Adding baryon acoustic oscillation distance measurements gives similar constraints: w =−1.027 ± 0.055. Our supernova measurements provide the most stringent constraints to date on the nature of dark energy.
ISSN: 0004-6361
ISSN: 1432-0746
ISSN: 1432-0746
DOI: 10.1051/0004-6361/201423413

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