title: Reconstructing the cosmic equation of state from supernova distances.
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(phi) of the scalar field driving this acceleration, and the associated equation of state w(phi). Our method is based on a versatile analytical form for the luminosity distance D(L), optimized to fit observed distances to distant supernovae and differentiated to yield V(straight phi) and w(straight phi). Our results favor w(phi) approximately -1 at the present epoch, steadily increasing with redshift. A cosmological constant is consistent with our results.
authors.affiliation: Inter-University Centre for Astronomy & Astrophysics, Puné 411 007, India. saini@iucaa.ernet.in
authors.forename: T D
authors.initials: TD
authors.lastname: Saini
authors.forename: S
authors.initials: S
authors.lastname: Raychaudhury
authors.forename: V
authors.initials: V
authors.lastname: Sahni
authors.forename: A A
authors.initials: AA
authors.lastname: Starobinsky
mesh_terms: D001256:Astronomy / Q000379:methods; D003359:Cosmic Radiation; D008027:Light; D010825:Physics / Q000379:methods