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Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples

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  • M. Betoule
  • R. Kessler
  • J. Guy
  • J. Mosher
  • D. Hardin
  • R. Biswas
  • P. Astier
  • P. El-Hage
  • M. Konig
  • S. Kuhlmann
  • J. Marriner
  • R. Pain
  • N. Regnault
  • C. Balland
  • B. A. Bassett
  • P. J. Brown
  • H. Campbell
  • R. G. Carlberg
  • F. Cellier-Holzern
  • D. Cinabro
  • A. Conley
  • C. B. D'Andrea
  • D. L. DePoy
  • M. Doi
  • R. S. Ellis
  • S. Fabbro
  • A. V. Filippenko
  • R. J. Foley
  • J. A. Frieman
  • D. Fouchez
  • L. Galbany
  • A. Goobar
  • R. R. Gupta
  • G. J. Hill
  • R. Hlozek
  • C. J. Hogan
  • D. A. Howell
  • S. W. Jha
  • L. Le Guillou
  • G. Leloudas
  • C. Lidrnan
  • J. L. Marshall
  • A. Moeller
  • A. M. Mourao
  • J. Neveu
  • R. Nichol
  • M. D. Olmstead
  • N. Palanque-Delabrouille
  • S. Perlinutter
  • J. L. Prieto
  • C. J. Pritchet
  • M. Richinond
  • A. G. Riess
  • V. Ruhlmann-Kleider
  • M. Sako
  • K. Sehahmaneche
  • D. P. Schneider
  • M. Smith
  • J. Sollerman
  • M. Sullivan
  • N. A. Walton
  • C. J. Wheeler
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Article number22
<mark>Journal publication date</mark>08/2014
<mark>Journal</mark>Astronomy and Astrophysics
Volume568
Number of pages32
Publication StatusPublished
Early online date8/08/14
<mark>Original language</mark>English

Abstract

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.