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

TL;DR

This paper performs a detailed tomographic analysis of galaxy clustering from SDSS-III BOSS DR12 data, measuring BAO parameters across multiple redshifts to improve cosmological constraints, especially on dark energy.

Contribution

It introduces a tomographic BAO analysis with nine redshift slices, enhancing the precision of cosmological parameter constraints compared to previous non-tomographic methods.

Findings

Achieved 1.3%-2.2% precision for D_A(z)/r_d

Achieved 2.1%-6.0% precision for H(z)r_d

Improved dark energy Figure of Merit by 24% with 9-bin analysis

Abstract

We perform a tomographic baryon acoustic oscillations analysis using the two-point galaxy correlation function measured from the combined sample of BOSS DR12, which covers the redshift range of $0.2<z<0.75$. Splitting the sample into multiple overlapping redshift slices to extract the redshift information of galaxy clustering, we obtain a measurement of $D_A(z)/r_d$ and $H(z)r_d$ at nine effective redshifts with the full covariance matrix calibrated using MultiDark-Patchy mock catalogues. Using the reconstructed galaxy catalogues, we obtain the precision of $1.3\%-2.2\%$ for $D_A(z)/r_d$ and $2.1\%-6.0\%$ for $H(z)r_d$. To quantify the gain from the tomographic information, we compare the constraints on the cosmological parameters using our 9-bin BAO measurements, the consensus 3-bin BAO and RSD measurements at three effective redshifts in \citet{Alam2016}, and the non-tomographic (1-bin) BAO measurement at a single effective redshift. Comparing the 9-bin with 1-bin constraint result, it can improve the dark energy Figure of Merit by a factor of 1.24 for the Chevallier-Polarski-Linder parametrisation for equation of state parameter $w_{\rm DE}$. The errors of $w_0$ and $w_a$ from 9-bin constraints are slightly improved when compared to the 3-bin constraint result.