The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: tomographic BAO analysis of DR12 combined sample in configuration space

We perform a tomographic baryon acoustic oscillations (BAOs) analysisusing the two-point galaxy correlation function measured from thecombined sample of Baryon Oscillation Spectroscopic Survey Data Release12 (BOSS DR12), which covers the redshift range of 0.2 z 0.75.Upon splitting the sample into multiple overlapping redshift slices toextract the redshift information of galaxy clustering, we obtain ameasurement of D_A(z)/r_d and H(z)r_d atnine effective redshifts with the full covariance matrix calibratedusing MultiDark-Patchy mock catalogues. Using the reconstructed galaxycatalogues, we obtain the precision of 1.3-2.2 per cent forD_A(z)/r_d and 2.1-6.0 per cent forH(z)r_d. To quantify the gain from the tomographicinformation, we compare the constraints on the cosmological parametersusing our nine-bin BAO measurements, the consensus three-bin BAO andredshift space distortion measurements at three effective redshifts inAlam et al., and the non-tomographic (one-bin) BAO measurement at asingle effective redshift. Comparing the nine-bin with one-binconstraint result, it can improve the dark energy Figure of Merit by afactor of 1.24 for the Chevallier-Polarski-Linder parametrization forequation-of-state parameter w_DE. The errors of w₀and w_a from nine-bin constraints are slightly improved whencompared to the three-bin constraint result.