The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: measurement of the growth rate of structure from the anisotropic correlation function between redshift 0.8 and 2.2

TL;DR

The paper present a full-shape anisotropic clustering analysis of the DR14 eBOSS quasar sample (0.8<z<2.2) using CLPT-GS to model redshift-space distortions and AP distortions. It validates the modeling with OuterRim mocks and employs EZ/QPM approximate mocks for covariance, delivering robust measurements of $f\sigma_8$, $H(z)$, and $D_A(z)$ at $z_{\rm eff}=1.52$, consistent with flat $\Lambda$CDM and GR. The analysis demonstrates strong agreement between multipole and wedge approaches and shows that photometric and spectroscopic systematics can be controlled with advanced weighting schemes. The results provide a high-redshift growth-rate constraint in concert with companion DR14 papers, illustrating the complementarity and robustness of full-shape analyses for the final eBOSS quasar sample and informing future DESI/Euclid-scale surveys.

Abstract

We present the clustering measurements of quasars in configuration space based on the Data Release 14 (DR14) of the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey. This dataset includes 148,659 quasars spread over the redshift range $0.8\leq z \leq 2.2$ and spanning 2112.9 square degrees. We use the Convolution Lagrangian Perturbation Theory (CLPT) approach with a Gaussian Streaming (GS) model for the redshift space distortions of the correlation function and demonstrate its applicability for dark matter halos hosting eBOSS quasar tracers. At the effective redshift $z_{\rm eff} = 1.52$, we measure the linear growth rate of structure $fσ_{8}(z_{\rm eff})= 0.426 \pm 0.077$, the expansion rate $H(z_{\rm eff})= 159^{+12}_{-13}(r_{s}^{\rm fid}/r_s){\rm km.s}^{-1}.{\rm Mpc}^{-1}$, and the angular diameter distance $D_{A}(z_{\rm eff})=1850^{+90}_{-115}\,(r_s/r_{s}^{\rm fid}){\rm Mpc}$, where $r_{s}$ is the sound horizon at the end of the baryon drag epoch and $r_{s}^{\rm fid}$ is its value in the fiducial cosmology. The quoted errors include both systematic and statistical contributions. The results on the evolution of distances are consistent with the predictions of flat $Λ$-Cold Dark Matter ($Λ$-CDM) cosmology with Planck parameters, and the measurement of $fσ_{8}$ extends the validity of General Relativity (GR) to higher redshifts($z>1$) This paper is released with companion papers using the same sample. The results on the cosmological parameters of the studies are found to be in very good agreement, providing clear evidence of the complementarity and of the robustness of the first full-shape clustering measurements with the eBOSS DR14 quasar sample.

Figures (21)

• Figure 1: Footprint of the DR14Q catalog used for this analysis. The upper (lower) panel displays the South (Nothr) Galactic Cap resulting in a total effective area of 2112.9 deg$^2$. Each object is color-coded according to the completeness of the sector to which it belongs (object in purple have completeness between $0.5$ and $0.8$)
• Figure 2: Redshift distribution of the objects in the DR14 catalog corresponding to the CORE sample. The orange histogram shows the known quasars at the start of eBOSS data taking. Objects in $0.8\leq z \leq 2.2$ are kept for this analysis.
• Figure 3: Distribution of the completeness $C_{\rm eBOSS}$ per sector. Sectors with completeness smaller than 0.9 correspond to overlaping plates regions where only one plate has currently been measured. Objects with $C_{\rm eBOSS}>0.5$ are not considered for clustering analysis.
• Figure 4: Physical distributions (solid lines) of $\Delta v = \Delta z \cdot c / (1 + z)$ between different redshift estimates for two redshift bins in our redshift range. The dotted line shows a gaussian distribution of width given by the survey requirements (see text). The most important feature is that the observed distributions present large non-Gaussian tails that extend to 3000 km s$^{-1}$. At low redshifts (upper panel), the distributions are mostly symmetric although minor shifts can be observed. At high redshifts (lower panel), the distribution obtained for ${z}_{\rm PCA}-{z}$ (red) is asymmetric, and could yield systematic shifts in the separation of quasars
• Figure 6: Top panel: Redshift efficiency as a function of the fiber number. The vertical dotted line shows the delimitation between the 2 spectrographs. Bottom panels: Redshift efficiency as a function of the focal plane coordinates for the NGC (middle panel) and SGC (lower panel). The fiber number goes clockwise from 0 to 1000.