paper

Transition Redshift: New constraints from parametric and nonparametric methods

arXiv:1503.08543 · doi:10.1088/1475-7516/2015/12/045

Abstract

In this paper, we use the Cosmokinematics approach to study the accelerated expansion of the Universe. This is a model independent approach and depends only on the assumption that the Universe is homogeneous and isotropic and is described by the FRW metric. We parametrize the deceleration parameter, , to constrain the transition redshift () at which the expansion of the Universe goes from a decelerating to an accelerating phase. We use three different parametrizations of namely, $q_\I(z)=q_{\textnormal{\tiny\textsc{1}}}+q_{\textnormal{\tiny\textsc{2}}}z$, $q_\II (z) = q_\3 + q_\4 \ln (1 + z)$ and $q_\III(z)=\frac{1}{2}+\frac{q_{\textnormal{\tiny\textsc{5}}}}{(1+z)^2}$. A joint analysis of the age of galaxies, strong lensing and supernovae Ia data indicates that the transition redshift is less than unity i.e. . We also use a nonparametric approach (LOESS+SIMEX) to constrain . This too gives which is consistent with the value obtained by the parametric approach.

Accepted for publication in JCAP

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