The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR16 luminous red galaxy and emission line galaxy samples: cosmic distance and structure growth measurements using multiple tracers in configuration space

Abstract

We perform a multi-tracer analysis using the complete Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS) DR16 luminous red galaxy (LRG) and the DR16 emission line galaxy (ELG) samples in the configuration space, and successfully detect a cross correlation between the two samples, and find the growth rate to be $f\ddot{I}{ƒ}_8=0.342\pm 0.085$ ($\sim 25$ per cent accuracy) from the cross sample alone. We perform a joint measurement of the baryonic acoustic oscillation (BAO) and redshift space distortion (RSD) parameters at a single effective redshift of $z_{\mathrm{eff}}=0.77$, using the auto- and cross-correlation functions of the LRG and ELG samples, and find that the comoving angular diameter distance $D_M(z_{\mathrm{eff}})/r_d=18.85\pm 0.38$, the Hubble distance $D_H(z_{\mathrm{eff}})/r_d=19.64\pm 0.57$, and $f\ddot{I}{ƒ}_8(z_{\mathrm{eff}})=0.432\pm 0.038$, which is consistent with a $\hat{I}›$CDM model at $68\%$ CL. Compared to the single-tracer analysis on the LRG sample, the Figure of Merit (FoM) of $\hat{I}{\pm }_{\perp },\hat{I}{\pm }_{||}$ and $f\ddot{I}{ƒ}_8$ is improved by a factor of $1.11$ in our multi-tracer analysis, and in particular, the statistical uncertainty of $f\ddot{I}{ƒ}_8$ is reduced by $11.6\%$.

15 pages, 13 figures, 2 tables; MNRAS accepted; The BAO and RSD measurements and the covariance matrix are made available at https://github.com/ytcosmo/MultiTracerBAORSD/