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Register a new userThe Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: BAO and RSD measurements from the anisotropic power spectrum of the Quasar sample between redshift 0.8 and 2.2
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Richard Neveux
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We measure the clustering of quasars of the final data release (DR16) of eBOSS. The sample contains $343,708$ quasars between redshifts $0.8leq zleq2.2$ over $4699,mathrm{deg}^2$. We calculate the Legendre multipoles (0,2,4) of the anisotropic power spectrum and perform a BAO and a Full-Shape (FS) analysis at the effective redshift $z{rm eff}=1.480$. The errors include systematic errors that amount to 1/3 of the statistical error. The systematic errors comprise a modelling part studied using a blind N-Body mock challenge and observational effects studied with approximate mocks to account for various types of redshift smearing and fibre collisions. For the BAO analysis, we measure the transverse comoving distance $D_{rm M}(z_{rm eff})/r_{rm drag}=30.60pm{0.90}$ and the Hubble distance $D_{rm H}(z_{rm eff})/r_{rm drag}=13.34pm{0.60}$. This agrees with the configuration space analysis, and the consensus yields: $D_{rm M}(z_{rm eff})/r_{rm drag}=30.69pm{0.80}$ and $D_{rm H}(z_{rm eff})/r_{rm drag}=13.26pm{0.55}$. In the FS analysis, we fit the power spectrum using a model based on Regularised Perturbation Theory, which includes Redshift Space Distortions and the Alcock-Paczynski effect. The results are $D_{rm M}(z_{rm eff})/r_{rm drag}=30.68pm{0.90}$ and $D_{rm H}(z_{rm eff})/r_{rm drag}=13.52pm{0.51}$ and we constrain the linear growth rate of structure $f(z_{rm eff})sigma_8(z_{rm eff})=0.476pm{0.047}$. Our results agree with the configuration space analysis. The consensus analysis of the eBOSS quasar sample yields: $D_{rm M}(z_{rm eff})/r_{rm drag}=30.21pm{0.79}$, $D_{rm H}(z_{rm eff})/r_{rm drag}=3.23pm{0.47}$ and $f(z_{rm eff})sigma_8(z_{rm eff})=0.462pm{0.045}$ and is consistent with a flat $Lambda {rm CDM}$ cosmological model using Planck results.
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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 present measurements of the Baryon Acoustic Oscillation (BAO) scale in redshift-space using the clustering of quasars. We consider a sample of 147,000 quasars from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) distributed over 2044 square degrees with redshifts $0.8 < z < 2.2$ and measure their spherically-averaged clustering in both configuration and Fourier space. Our observational dataset and the 1400 simulated realizations of the dataset allow us to detect a preference for BAO that is greater than 2.8$sigma$. We determine the spherically averaged BAO distance to $z = 1.52$ to 3.8 per cent precision: $D_V(z=1.52)=3843pm147 left(r_{rm d}/r_{rm d, fid}right) $Mpc. This is the first time the location of the BAO feature has been measured between redshifts 1 and 2. Our result is fully consistent with the prediction obtained by extrapolating the Planck flat $Lambda$CDM best-fit cosmology. All of our results are consistent with basic large-scale structure (LSS) theory, confirming quasars to be a reliable tracer of LSS, and provide a starting point for numerous cosmological tests to be performed with eBOSS quasar samples. We combine our result with previous, independent, BAO distance measurements to construct an updated BAO distance-ladder. Using these BAO data alone and marginalizing over the length of the standard ruler, we find $Omega_{Lambda} > 0$ at 6.6$sigma$ significance when testing a $Lambda$CDM model with free curvature.
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 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 $0.8leq z leq 2.2$ 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 $fsigma_{8}(z_{rm eff})= 0.426 pm 0.077$, 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 $Lambda$-Cold Dark Matter ($Lambda$-CDM) cosmology with Planck parameters, and the measurement of $fsigma_{8}$ 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.
We measure the growth rate and its evolution using the anisotropic clustering of the extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 14 (DR14) quasar sample, which includes $148,659$ quasars covering the wide redshift range of $0.8 < z < 2.2$ and a sky area of $2112.90$ $rm deg^2$. To optimise measurements we deploy a redshift-dependent weighting scheme, which allows us to avoid binning, and perform the data analysis consistently including the redshift evolution across the sample. We perform the analysis in Fourier space, and use the redshift evolving power spectrum multipoles to measure the redshift space distortion parameter $fsigma_8$ and parameters controlling the anisotropic projection of the cosmological perturbations. We measure $f sigma_8(z=1.52)=0.43 pm 0.05 $ and $dfsigma_8/dz (z=1.52)= - 0.16 pm 0.08$, consistent with the expectation for a $Lambda$CDM cosmology as constrained by the Planck experiment.
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