Supernova Limits on the Cosmic Equation of State
Author
Garnavich, Peter M.
Jha, Saurabh
Challis, Peter
Clocchiatti, Alejandro
Diercks, Alan
Filippenko, Alexei V.
Gilliland, Ron L.
Hogan, Craig J.
Kirshner, Robert P.
Leibundgut, Bruno
Phillips, M. M.
Reiss, David
Riess, Adam G.
Schmidt, Brian P.
Schommer, Robert A.
Smith, R. Chris
Spyromilio, Jason
Stubbs, Chris
Suntzeff, Nicholas B.
Tonry, John
Carroll, Sean M.
Published Version
https://doi.org/10.1086/306495Metadata
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Garnavich, Peter M., Saurabh Jha, Peter Challis, Alejandro Clocchiatti, Alan Diercks, Alexei V. Filippenko, Ron L. Gilliland, et al. 1998. “Supernova Limits on the Cosmic Equation of State.” The Astrophysical Journal 509 (1): 74–79. https://doi.org/10.1086/306495.Abstract
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, alpha(x) = P-x/rho(x), must be less than -0.55 (95% confidence) for any value of Omega(m), and it is further limited to alpha(x) < -0.60 (95% confidence) if Omega(m), is assumed to be greater than 0.1. These values are inconsistent with the unknown component being topological defects such as domain walls, strings, or textures. The supernova (SN) data are consistent with a cosmological constant (alpha(x) = -1) or a scalar field that has had, on average, an equation-of-state parameter similar to the cosmological constant value of -1 over the redshift range of z approximate to 1 to the present. SN and cosmic microwave background observations give complementary constraints on the densities of matter and the unknown component. If only matter and vacuum energy are considered, then the current combined data sets provide direct evidence for a spatially flat universe with Omega(tot) = Omega(m) + Omega(Lambda) = 0.94 +/- 0.26 (1 sigma).Terms of Use
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