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Reconstructing the Cosmic Equation of State from Supernova distances

Tarun Deep Saini, Somak Raychaudhury, Varun Sahni, A. A. Starobinsky

astro-pharXiv:astro-ph/9910231

Abstract

Observations of high-redshift supernovae indicate that the universe is accelerating. Here we present a model-independent method for estimating the form of the potential V(ϕ) of the scalar field driving this acceleration, and the associated equation of state wϕ. Our method is based on a versatile analytical form for the luminosity distance DL, optimized to fit observed distances to distant supernovae and differentiated to yield V(ϕ) and wϕ. Our results favor wϕ -1 at the present epoch, steadily increasing with redshift. A cosmological constant is consistent with our results.

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