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Register a new userThe Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Growth rate of structure measurement from anisotropic clustering analysis in configuration space between redshift 0.6 and 1.1 for the Emission Line Galaxy sample
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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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We analyse the large-scale clustering in Fourier space of emission line galaxies (ELG) from the Data Release 16 of the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey. The ELG sample contains 173,736 galaxies covering 1,170 square degrees in the redshift range $0.6 < z < 1.1$. We perform a BAO measurement from the post-reconstruction power spectrum monopole, and study redshift space distortions (RSD) in the first three even multipoles. Photometric variations yield fluctuations of both the angular and radial survey selection functions. Those are directly inferred from data, imposing integral constraints which we model consistently. The full data set has only a weak preference for a BAO feature ($1.4sigma$). At the effective redshift $z_{rm eff} = 0.845$ we measure $D_{rm V}(z_{rm eff})/r_{rm drag} = 18.33_{-0.62}^{+0.57}$, with $D_{rm V}$ the volume-averaged distance and $r_{rm drag}$ the comoving sound horizon at the drag epoch. In combination with the RSD measurement, at $z_{rm eff} = 0.85$ we find $fsigma_8(z_{rm eff}) = 0.289_{-0.096}^{+0.085}$, with $f$ the growth rate of structure and $sigma_8$ the normalisation of the linear power spectrum, $D_{rm H}(z_{rm eff})/r_{rm drag} = 20.0_{-2.2}^{+2.4}$ and $D_{rm M}(z_{rm eff})/r_{rm drag} = 19.17 pm 0.99$ with $D_{rm H}$ and $D_{rm M}$ the Hubble and comoving angular distances, respectively. These results are in agreement with those obtained in configuration space, thus allowing a consensus measurement of $fsigma_8(z_{rm eff}) = 0.315 pm 0.095$, $D_{rm H}(z_{rm eff})/r_{rm drag} = 19.6_{-2.1}^{+2.2}$ and $D_{rm M}(z_{rm eff})/r_{rm drag} = 19.5 pm 1.0$. This measurement is consistent with a flat $Lambda$CDM model with Planck parameters.
We present the Emission Line Galaxy (ELG) sample of the extended Baryon Oscillation Spectroscopic Survey (eBOSS) from the Sloan Digital Sky Survey IV Data Release 16 (DR16). After describing the observations and redshift measurement for the 269,243 observed ELG spectra over 1170 deg$^2$, we present the large-scale structure catalogues, which are used for the cosmological analysis. These catalogues contain 173,736 reliable spectroscopic redshifts between 0.6 and 1.1, along with the associated random catalogues quantifying the extent of observations, and the appropriate weights to correct for non-cosmological fluctuations. We perform a spherically averaged baryon acoustic oscillations (BAO) measurement in configuration space, with density field reconstruction: the data 2-point correlation function shows a feature consistent with that of the BAO, providing a 3.2-percent measurement of the spherically averaged BAO distance $D_V(z_{rm eff})/r_{rm drag} = 18.23pm 0.58$ at the effective redshift $z_{rm eff}=0.845$.
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 measure the anisotropic clustering of the quasar sample from Data Release 16 (DR16) of the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey (eBOSS). A sample of $343,708$ spectroscopically confirmed quasars between redshift $0.8<z<2.2$ are used as tracers of the underlying dark matter field. In comparison with DR14 sample, the final sample doubles the number of objects as well as the survey area. In this paper, we present the analysis in configuration space by measuring the two-point correlation function and decompose using the Legendre polynomials. For the full-shape analysis of the Legendre multipole moments, we measure the BAO distance and the growth rate of the cosmic structure. At an effective redshift of $z_{rm eff}=1.48$, we measure the comoving angular diameter distance $D_{rm M}(z_{rm eff})/r_{rm drag} = 30.66pm0.88$, the Hubble distance $D_{rm H}(z_{rm eff})/r_{rm drag} = 13.11pm0.52$, and the growth rate $fsigma_8(z_{rm eff}) = 0.439pm0.048$. The accuracy of these measurements is confirmed using an extensive set of mock simulations developed for the quasar sample. The uncertainties on the distance and growth rate measurements have been reduced substantially ($sim 45%$ and $sim30%$) with respect to the DR14 results. We also perform a BAO-only analysis to cross check the robustness of the methodology of the full-shape analysis. Combining our analysis with the Fourier space analysis, we arrive at $D^{bf{c}}_{rm M}(z_{rm eff})/r_{rm drag} = 30.22 pm 0.79$, $D^{bf{c}}_{rm H}(z_{rm eff})/r_{rm drag} = 13.26 pm 0.47$, and $fsigma_8^{bf{c}}(z_{rm eff}) = 0.464 pm 0.045$.
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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