Supernova limits on the cosmic equation of state

  title={Supernova limits on the cosmic equation of state},
  author={Peter M. Garnavich and Saurabh W. Jha and Peter M. Challis and Alejandro Clocchiatti and Alan H. Diercks and Alexei V. Filippenko and Ronald L. Gilliland and Craig Hogan and R. P. Kirshner and Bruno Leibundgut and Mark M. Phillips and David J. Reiss and Adam G. Riess and B P Schmidt and Robert A. Schommer and R. C. Smith and Jason Spyromilio and Christopher W. Stubbs and Nicholas B. Suntzeff and John L. Tonry and S. M. Carroll CfA and Universidad Catolica and University of Washington and Ucb and Stsci and Eső and Ctio and Mssso and University of Michigan and University of Hawaii and Ucsb},
  journal={The Astrophysical Journal},
We use Type Ia supernovae studied by the High-z Supernova Search Team to constrain the properties of an energy component that may have contributed to accelerating the cosmic expansion. We find that for a flat geometry the equation-of-state parameter for the unknown component, αx = Px/ρx, must be less than -0.55 (95% confidence) for any value of Ωm, and it is further limited to αx < -0.60 (95% confidence) if Ωm is assumed to be greater than 0.1. These values are inconsistent with the unknown… 

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