Paper: astro-ph/0601453
Date: Thu, 19 Jan 2006 20:54:58 GMT (27kb)

Title: Observational constraints on the acceleration of the Universe

Authors: Yungui Gong, Anzhong Wang

Comments: 9 figures, revtex
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We first parameterize the deceleration parameter to discuss its behavior. The
advantage of this parametrization is that we do not need to assume any
underlying theory of gravity. By fitting the model to the 157 gold sample
supernova Ia data, we find strong evidence that the Universe is currently
accelerating and it accelerated in the past. By fitting the model to the 115
nearby and Supernova Legacy Survey supernova Ia data, the evidence that the
Universe is currently accelerating is weak and there is strong evidence that
the Universe once accelerated in the past. We then use a dark energy
parametrization to discuss the problem again. If we fit the model to the
supernova Ia data alone, we find weak evidence that the Universe is
accelerating and the current matter density is higher than that measured from
other experiments. Therefore we add the Sloan Digital Sky Survey data to
constrain the dark energy model. The behavior of the deceleration parameter is
almost the same as that obtained from parameterizing the deceleration
parameter.

\\ ( http://arXiv.org/abs/astro-ph/0601453 , 27kb)