Testing anisotropy and comparison of various supernova data constraints on dark energy model.

We study the possibly existing anisotropy in the accelerating expansion Universe with various supernovae data, the baryon acoustic oscillation and the observational Hubble data. We present combined results from these probes, deriving constraints on the equation of state (EoS), w , of dark energy (DE) and its energy density in the Universe. We fit the cosmological parameters simultaneously employing the maximum likelihood analysis. By combining data and considering anisotropy effects, we find that the EoS of DE are w (0. 0 1 ≤ z ≤ 1. 7 5) = − 0. 9 9 8 ± 0. 0 5 6 , w (0 < z < 1) = − 1. 0 8 6 ± 0. 0 6 5 , w (0. 1 5 < z < 1. 1) = − 1. 0 9 6 ± 0. 1 2 3 and w (0. 0 1 < z < 2. 3) = − 1. 0 4 2 6 ± 0. 0 5 4 within 1 σ ′ confidence level. Finally, introducing an anisotropy appears to improve the fit to observations with respect to that provided by an isotropic w CDM model. [ABSTRACT FROM AUTHOR]