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Register a new userThe completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: measurement of the growth rate of structure from the small-scale clustering of the luminous red galaxy sample
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We measure the small-scale clustering of the Data Release 16 extended Baryon Oscillation Spectroscopic Survey Luminous Red Galaxy sample, corrected for fibre-collisions using Pairwise Inverse Probability weights, which give unbiased clustering measurements on all scales. We fit to the monopole and quadrupole moments and to the projected correlation function over the separation range $7-60,h^{-1}$Mpc with a model based on the Aemulus cosmological emulator to measure the growth rate of cosmic structure, parameterized by $fsigma_8$. We obtain a measurement of $fsigma_8(z=0.737)=0.408pm0.038$, which is $1.4sigma$ lower than the value expected from 2018 Planck data for a flat $Lambda$CDM model, and is more consistent with recent weak-lensing measurements. The level of precision achieved is 1.7 times better than more standard measurements made using only the large-scale modes of the same sample. We also fit to the data using the full range of scales $0.1-60,h^{-1}$Mpc modelled by the Aemulus cosmological emulator and find a $4.5sigma$ tension in the amplitude of the halo velocity field with the Planck+$Lambda$CDM model, driven by a mismatch on the non-linear scales. This may not be cosmological in origin, and could be due to a breakdown in the Halo Occupation Distribution model used in the emulator. Finally, we perform a robust analysis of possible sources of systematics, including the effects of redshift uncertainty and incompleteness due to target selection that were not included in previous analyses fitting to clustering measurements on small scales.
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We present a void clustering analysis in configuration-space using the completed Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS) DR16 samples. These samples consist of Luminous Red Galaxies (LRG) combined with the high redshift tail of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) DR12 CMASS galaxies (called as LRG+CMASS sample), Emission Line Galaxies (ELG) and quasars (QSO). We build void catalogues from the three eBOSS DR16 samples using a ZOBOV-based algorithm, providing 2,814 voids, 1,801 voids and 4,347 voids in the LRG+CMASS, ELG and QSO samples, respectively, spanning the redshift range $0.6<z<2.2$. We measure the redshift space distortions (RSD) around voids using the anisotropic void-galaxy cross-correlation function and we extract the distortion parameter $beta$. We test the methodology on realistic simulations before applying it to the data, and we investigate all our systematic errors on these mocks. We find $beta^{rm LRG}(z=0.74)=0.415pm0.087$, $beta^{rm ELG}(z=0.85)=0.665pm0.125$ and $beta^{rm QSO}(z=1.48)=0.313pm0.134$, for the LRG+CMASS, ELG and QSO sample, respectively. The quoted errors include systematic and statistical contributions. In order to convert our measurements in terms of the growth rate $fsigma_8$, we use consensus values of linear bias from the eBOSS DR16 companion papers~citep{eBOSScosmo}, resulting in the following constraints: $fsigma_8(z=0.74)=0.50pm0.11$, $fsigma_8(z=0.85)=0.52pm0.10$ and $fsigma_8(z=1.48)=0.30pm0.13$. Our measurements are consistent with other measurements from eBOSS DR16 using conventional clustering techniques.
We present an analysis of the anisotropic redshift-space void-galaxy correlation in configuration space using the Sloan Digital Sky Survey extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 16 luminous red galaxy (LRG) sample. This sample consists of LRGs between redshifts 0.6 and 1.0, combined with the high redshift $z>0.6$ tail of the Baryon Oscillation Spectroscopic Survey Data Release 12 CMASS sample. We use a reconstruction method to undo redshift-space distortion (RSD) effects from the galaxy field before applying a watershed void-finding algorithm to remove bias from the void selection. We then perform a joint fit to the multipole moments of the correlation function for the growth rate $fsigma_8$ and the geometrical distance ratio $D_M/D_H$, finding $fsigma_8(z_mathrm{eff})=0.356pm0.079$ and $D_M/D_H(z_mathrm{eff})=0.868pm0.017$ at the effective redshift $z_mathrm{eff}=0.69$ of the sample. The posterior parameter degeneracies are orthogonal to those from galaxy clustering analyses applied to the same data, and the constraint achieved on $D_M/D_H$ is significantly tighter. In combination with the consensus galaxy BAO and full-shape analyses of the same sample, we obtain $fsigma_8=0.447pm0.039$, $D_M/r_d=17.48pm0.23$ and $D_H/r_d=20.10pm0.34$. These values are in good agreement with the $Lambda$CDM model predictions and represent reductions in the uncertainties of $13%$, $23%$ and $28%$ respectively compared to the combined results from galaxy clustering, or an overall reduction of 55% in the allowed volume of parameter space.
We present the cosmological analysis of the configuration-space anisotropic clustering in the completed Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS) DR16 galaxy sample. This sample consists of luminous red galaxies (LRGs) spanning the redshift range $0.6 < z < 1$, at an effective redshift of $z_{rm eff}=0.698$. It combines 174 816 eBOSS LRGs and 202 642 BOSS CMASS galaxies. We extract and model the baryon acoustic oscillations (BAO) and redshift-space distortions (RSD) features from the galaxy two-point correlation function to infer geometrical and dynamical cosmological constraints. The adopted methodology is extensively tested on a set of realistic simulations. The correlations between the inferred parameters from the BAO and full-shape correlation function analyses are estimated. This allows us to derive joint constraints on the three cosmological parameter combinations: $D_M(z)/r_d$, $D_H(z)/r_d$ and $fsigma_8(z)$, where $D_M$ is the comoving angular diameter distance, $D_H$ is Hubble distance, $r_d$ is the comoving BAO scale, $f$ is the linear growth rate of structure, and $sigma_8$ is the amplitude of linear matter perturbations. After combining the results with those from the parallel power spectrum analysis of Gil-Marin et al. 2020, we obtain the constraints: $D_M/r_d = 17.65 pm 0.30$, $D_H/r_d = 19.77 pm 0.47$, $fsigma_8 = 0.473 pm 0.044$. These measurements are consistent with a flat $Lambda$CDM model with standard gravity.
We analyse the clustering of the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey Data Release 16 luminous red galaxy sample (DR16 eBOSS LRG) in combination with the high redshift tail of the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey Data Release 12 (DR12 BOSS CMASS). We measure the redshift space distortions (RSD) and also extract the longitudinal and transverse baryonic acoustic oscillation (BAO) scale from the anisotropic power spectrum signal inferred from 377,458 galaxies between redshifts 0.6 and 1.0, with effective redshift of $z_{rm eff}=0.698$ and effective comoving volume of $2.72,{rm Gpc}^3$. After applying reconstruction we measure the BAO scale and infer $D_H(z_{rm eff})/r_{rm drag} = 19.30pm 0.56$ and $D_M(z_{rm eff})/r_{rm drag} =17.86 pm 0.37$. When we perform a redshift space distortions analysis on the pre-reconstructed catalogue on the monopole, quadrupole and hexadecapole we find, $D_H(z_{rm eff})/r_{rm drag} = 20.18pm 0.78$, $D_M(z_{rm eff})/r_{rm drag} =17.49 pm 0.52$ and $fsigma_8(z_{rm eff})=0.454pm0.046$. We combine both sets of results along with the measurements in configuration space of cite{LRG_corr} and report the following consensus values: $D_H(z_{rm eff})/r_{rm drag} = 19.77pm 0.47$, $D_M(z_{rm eff})/r_{rm drag} = 17.65pm 0.30$ and $fsigma_8(z_{rm eff})=0.473pm 0.044$, which are in full agreement with the standard $Lambda$CDM and GR predictions. These results represent the most precise measurements within the redshift range $0.6leq z leq 1.0$ and are the culmination of more than 8 years of SDSS observations.
We present the anisotropic clustering of emission line galaxies (ELGs) from the Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 16 (DR16). Our sample is composed of 173,736 ELGs covering an area of 1170 deg$^2$ over the redshift range $0.6 leq z leq 1.1$. We use the Convolution Lagrangian Perturbation Theory in addition to the Gaussian Streaming Redshift-Space Distortions to model the Legendre multipoles of the anisotropic correlation function. We show that the eBOSS ELG correlation function measurement is affected by the contribution of a radial integral constraint that needs to be modelled to avoid biased results. To mitigate the effect from unknown angular systematics, we adopt a modified correlation function estimator that cancels out the angular modes from the clustering. At the effective redshift, $z_{rm eff}=0.85$, including statistical and systematical uncertainties, we measure the linear growth rate of structure $fsigma_8(z_{rm eff}) = 0.35pm0.10$, the Hubble distance $D_H(z_{rm eff})/r_{rm drag} = 19.1^{+1.9}_{-2.1}$ and the comoving angular diameter distance $D_M(z_{rm eff})/r_{rm drag} = 19.9pm1.0$. These results are in agreement with the Fourier space analysis, leading to consensus values of: $fsigma_8(z_{rm eff}) = 0.315pm0.095$, $D_H(z_{rm eff})/r_{rm drag} = 19.6^{+2.2}_{-2.1}$ and $D_M(z_{rm eff})/r_{rm drag} = 19.5pm1.0$, consistent with $Lambda$CDM model predictions with Planck parameters.
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