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arXiv · 0909.4365

The Equation of State of Tracker Fields

Takeshi Chiba
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Abstract

We derive the equation of state of tracker fields, which are typical examples of freezing quintessence (quintessence with the equation of state approaching toward -1), taking into account of the late-time departure from the tracker solution due to the nonzero density parameter of dark energy $\Omp$. We calculate the equation of state as a function of $\Omp$ for constant $\Gamma=VV"/(V')^2$ (during matter era) models. The derived equation of state contains a single parameter, $w_{(0)}$, which parametrizes the equation of state during the matter-dominated epoch. We derive observational constraints on $w_{(0)}$ and find that observational data are consistent with the cosmological constant: $-1.11< \wzero< -0.96 (1 \sigma)$.

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Takeshi Chiba. 2009-09-24. The Equation of State of Tracker Fields. https://doi.org/10.1103/physrevd.81.023515

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