Observational Constraints on the Nature of Dark Energy: First Cosmological Results from the ESSENCE Supernova Survey

We present constraints on the dark energy equation-of-state parameter, w = P/(ρc2), using 60 SNe Ia from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat universe. By including constraints on (ΩM, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1.05img1.gif (stat 1 σ) ± 0.13 (sys) and ΩM = 0.274img2.gif (stat 1 σ) with a best-fit χ2/dof of 0.96. These results are consistent with those reported by the Supernova Legacy Survey from the first year of a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present…

• NS
  National Science Foundation
• SI
  Smithsonian Institution
• UO
  University of Arizona
• CN
  Consejo Nacional de Investigaciones Científicas y Técnicas
• CN
  Conselho Nacional de Desenvolvimento Científico e Tecnológico
• ES
  European Southern Observatory
• SA
  Smithsonian Astrophysical Observatory
• NR
  National Research Council Canada
• AR
  Australian Research Council
• CN
  Comisión Nacional de Investigación Científica y Tecnológica