We perform an anisotropic clustering analysis of 1,133,326 galaxies from the Sloan Digital Sky Survey ( SDSS-III ) Baryon Oscillation Spectroscopic Survey ( BOSS ) Data Release ( DR ) 12 covering the redshift range 0.15 < z < 0.69 .
The geometrical distortions of the galaxy positions , caused by incorrect cosmological model assumptions , are captured in the anisotropic two-point correlation function on scales 6 – 40 h ^ { -1 } Mpc .
The redshift evolution of this anisotropic clustering is used to place constraints on the cosmological parameters .
We improve the methodology of Li et al .
2016 , to enable efficient exploration of high dimensional cosmological parameter spaces , and apply it to the Chevallier-Polarski-Linder parametrization of dark energy , w = w _ { 0 } + w _ { a } { z } / ( { 1 + z } ) .
In combination with the CMB , BAO , SNIa and H _ { 0 } from Cepheid data , we obtain \Omega _ { m } = 0.301 \pm 0.008 , w _ { 0 } = -1.042 \pm 0.067 , and w _ { a } = -0.07 \pm 0.29 ( 68.3 % CL ) .
Adding our new AP measurements to the aforementioned results reduces the error bars by \sim 30 – 40 % and improves the dark energy figure of merit by a factor of \sim 2 .
We check the robustness of the results using realistic mock galaxy catalogues .