Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples
Abstract
We present cosmological constraints from a joint analysis of type Ia supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The data set includes several low-redshift samples (z<0.1), all 3 seasons from the SDSS-II (0.05 < z < 0.4), and 3 years from SNLS (0.2 <z < 1) and totals \ntotc spectroscopically confirmed type Ia supernovae with high quality light curves. We have followed the methods and assumptions of the SNLS 3-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 (\nsdssc SNe), 2) inter-calibration 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. 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 LCDM cosmology we find Omega_m=0.295+-0.034 (stat+sys), a value consistent with the most recent CMB measurement from the Planck and WMAP experiments. Our result is 1.8sigma (stat+sys) different than the previously published result of SNLS 3-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 BAO distance measurements gives similar constraints: w=-1.027+-0.055.
Keywords
Cite
@article{arxiv.1401.4064,
title = {Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples},
author = {M. Betoule and R. Kessler and J. Guy and J. Mosher and D. Hardin and R. Biswas and P. Astier and P. El-Hage and M. Konig and S. Kuhlmann and J. Marriner and R. Pain and N. Regnault and C. Balland and B. A. Bassett and P. J. Brown and H. Campbell and R. G. Carlberg and F. Cellier-Holzem and D. Cinabro and A. Conley and C. B. D'Andrea and D. L. DePoy and M. Doi and R. S. Ellis and S. Fabbro and A. V. Filippenko and R. J. Foley and J. A. Frieman and D. Fouchez and L. Galbany and A. Goobar and R. R. Gupta and G. J. Hill and R. Hlozek and C. J. Hogan and I. M. Hook and D. A. Howell and S. W. Jha and L. Le Guillou and G. Leloudas and C. Lidman and J. L. Marshall and A. Möller and A. M. Mourão and J. Neveu and R. Nichol and M. D. Olmstead and N. Palanque-Delabrouille and S. Perlmutter and J. L. Prieto and C. J. Pritchet and M. Richmond and A. G. Riess and V. Ruhlmann-Kleider and M. Sako and K. Schahmaneche and D. P. Schneider and M. Smith and J. Sollerman and M. Sullivan and N. A. Walton and C. J. Wheeler},
journal= {arXiv preprint arXiv:1401.4064},
year = {2015}
}
Comments
30 pages, 18 figures, Submitted to A&A