Narrowing Constraints with Type Ia Supernovae: Converging on a Cosmological Constant

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dc.creatorSullivan, Scott
dc.creatorCooray, Asantha
dc.creatorHolz, Daniel E.
dc.date2007-06-26
dc.date.accessioned2026-07-07T10:56:25Z
dc.date.available2026-07-07T10:56:25Z
dc.descriptionWe apply a parameterization-independent approach to fitting the dark energy equation-of-state (EOS). Utilizing the latest type Ia supernova data, combined with results from the cosmic microwave background and baryon acoustic oscillations, we find that the dark energy is consistent with a cosmological constant. We establish independent estimates of the evolution of the dark energy EOS by diagonalizing the covariance matrix. We find three independent constraints, which taken together imply that the equation of state is more negative than -0.2 at the 68% confidence level in the redshift range 0<z<1.8, independent of the flat universe assumption. Our estimates argue against previous claims of dark energy ``metamorphosis,'' where the EOS was found to be strongly varying at low redshifts. Our results are inconsistent with extreme models of dynamical dark energy, both in the form of ``freezing'' models where the dark energy EOS begins with a value greater than -0.2 at z > 1.2 and rolls to a value of -1 today, and ``thawing'' models where the EOS is near -1 at high redshifts, but rapidly evolves to values greater than -0.85 at z < 0.2. Finally, we propose a parameterization-independent figure-of-merit, to help assess the ability of future surveys to constrain dark energy. While previous figures-of-merit presume specific dark energy parameterizations, we suggest a binning approach to evaluate dark energy constraints with a minimum number of assumptions.
dc.description16 pages, 6 figures, submitted to JCAP; A code to estimate binned & uncorrelated w(z) estimates from the supernovae Hubble diagram and most other cosmological data available from http://www.cooray.org/sn.html
dc.identifierhttps://arxiv.org/abs/0706.3730
dc.identifierhttp://arxiv.org/abs/0706.3730
dc.identifierJCAP0709:004,2007
dc.identifierdoi:10.1088/1475-7516/2007/09/004
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/186408
dc.subjectAstrophysics
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectHigh Energy Physics - Theory
dc.titleNarrowing Constraints with Type Ia Supernovae: Converging on a Cosmological Constant
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