ABSTRACT
We present the cosmological analysis of the configuration-space anisotropic clustering in the completed Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey (eBOSS) ...Data Release 16 galaxy sample. This sample consists of luminous red galaxies (LRGs) spanning the redshift range 0.6 < $z$ < 1, at an effective redshift of $z$eff = 0.698. It combines 174 816 eBOSS and 202 642 BOSS LRGs. We extract and model the baryon acoustic oscillation (BAO) and redshift-space distortion (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: DM($z$)/rd, DH($z$)/rd, and fσ8($z$), where DM is the comoving angular diameter distance, DH is the Hubble distance, rd is the comoving BAO scale, f is the linear growth rate of structure, and σ8 is the amplitude of linear matter perturbations. After combining the results with those from the parallel power spectrum analysis of Gil-Marin et al., we obtain the constraints: DM/rd = 17.65 ± 0.30, DH/rd = 19.77 ± 0.47, and fσ8 = 0.473 ± 0.044. These measurements are consistent with a flat Lambda cold dark matter model with standard gravity.
ABSTRACT
We present the joint analysis of Neutral Hydrogen (H i) Intensity Mapping observations with three galaxy samples: the Luminous Red Galaxy (LRG) and Emission Line Galaxy (ELG) samples from ...the eBOSS survey, and the WiggleZ Dark Energy Survey sample. The H i intensity maps are Green Bank Telescope observations of the redshifted $21\rm cm$ emission on $100 \, {\rm deg}^2$ covering the redshift range 0.6 < z < 1.0. We process the data by separating and removing the foregrounds present in the radio frequencies with FastI ICA. We verify the quality of the foreground separation with mock realizations, and construct a transfer function to correct for the effects of foreground removal on the H i signal. We cross-correlate the cleaned H i data with the galaxy samples and study the overall amplitude as well as the scale dependence of the power spectrum. We also qualitatively compare our findings with the predictions by a semianalytical galaxy evolution simulation. The cross-correlations constrain the quantity $\Omega _{\rm {H\,\small {I}}} b_{\rm {H\,\small {I}}} r_{\rm {H\,\small {I}},{\rm opt}}$ at an effective scale keff, where $\Omega _\rm {H\,\small {I}}$ is the H i density fraction, $b_\rm {H\,\small {I}}$ is the H i bias, and $r_{\rm {H\,\small {I}},{\rm opt}}$ the galaxy–hydrogen correlation coefficient, which is dependent on the H i content of the optical galaxy sample. At $k_{\rm eff}=0.31 \, h\,{\rm Mpc^{-1}}$ we find $\Omega _{\rm {H\,\small {I}}} b_{\rm {H\,\small {I}}} r_{\rm {H\,\small {I}},{\rm Wig}} = 0.58 \pm 0.09 \, {\rm (stat) \pm 0.05 \, {\rm (sys)}} \times 10^{-3}$ for GBT-WiggleZ, $\Omega _{\rm {H\,\small {I}}} b_{\rm {H\,\small {I}}} r_{\rm {H\,\small {I}},{\rm ELG}} = 0.40 \pm 0.09 \, {\rm (stat) \pm 0.04 \, {\rm (sys)}} \times 10^{-3}$ for GBT-ELG, and $\Omega _{\rm {H\,\small {I}}} b_{\rm {H\,\small {I}}} r_{\rm {H\,\small {I}},{\rm LRG}} = 0.35 \pm 0.08 \, {\rm (stat) \pm 0.03 \, {\rm (sys)}} \times 10^{-3}$ for GBT-LRG, at z ≃ 0.8. We also report results at $k_{\rm eff}=0.24$ and $k_{\rm eff}=0.48 \, h\,{\rm Mpc^{-1}}$. With little information on H i parameters beyond our local Universe, these are amongst the most precise constraints on neutral hydrogen density fluctuations in an underexplored redshift range.
We develop a new method, which is based on the optimal redshift weighting scheme, to extract the maximal tomographic information of baryonic acoustic oscillations (BAO) and redshift space distortions ...(RSD) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 14 quasar (DR14Q) survey. We validate our method using the Extended Zel’dovich mocks, and apply our pipeline to the eBOSS DR14Q sample in the redshift range of 0.8 < |$z$| < 2.2. We report a joint measurement of fσ_8 and two-dimensional BAO parameters D_A and H at four effective redshifts of |$z$|_eff = 0.98, 1.23, 1.52, and 1.94, and provide the full data covariance matrix. Using our measurement combined with BOSS DR12, Main Galaxy Sample (MGS), and 6 degree Field Galaxy Survey (6dFGS) BAO measurements, we find that the existence of dark energy is supported by observations at a 7.4σ significance level. Combining our measurement with BOSS DR12 and Planck observations, we constrain the gravitational growth index to be γ = 0.580 ± 0.082, which is fully consistent with the prediction of general relativity. This paper is part of a set that analyses the eBOSS DR14 quasar sample.
We present a measurement of the anisotropic void-galaxy cross-correlation function in the CMASS galaxy sample of the BOSS DR12 data release. We perform a joint fit to the data for redshift space ...distortions (RSD) due to galaxy peculiar velocities and anisotropies due to the Alcock-Paczynski (AP) effect, for the first time using a velocity field reconstruction technique to remove the complicating effects of RSD in the void center positions themselves. Fits to the void-galaxy function give a 1% measurement of the AP parameter combination DA(z)H(z)/c=0.4367±0.0045 at redshift z=0.57, where DA is the angular diameter distance and H the Hubble parameter, exceeding the precision obtainable from baryon acoustic oscillations (BAO) by a factor of ~3.5 and free of systematic errors. From voids alone we also obtain a 10% measure of the growth rate, fσ8(z=0.57)=0.501±0.051. The parameter degeneracies are orthogonal to those obtained from galaxy clustering. Combining void information with that from BAO and galaxy RSD in the same CMASS sample, we measure DA(0.57)/rs=9.383±0.077 (at 0.8% precision), H(0.57)rs=(14.05±0.14)103 kms−1 Mpc−1 (1%), and fσ8=0.453±0.022 (4.9%), consistent with cosmic microwave background (CMB) measurements from Planck. These represent a factor ~2 improvement in precision over previous results through the inclusion of void information. Fitting a flat cosmological constant ΛCDM model to these results in combination with Planck CMB data, we find up to an 11% reduction in uncertainties on H0 and Ωm compared to use of the corresponding BOSS consensus values. Constraints on extended models with nonflat geometry and a dark energy of state that differs from w=−1 show an even greater improvement.
We present a measurement of the baryon acoustic oscillation (BAO) scale at redshift z = 2.35 from the three-dimensional correlation of Lyman-α (Lyα) forest absorption and quasars. The study uses 266 ...590 quasars in the redshift range 1.77 < z < 3.5 from the Sloan Digital Sky Survey (SDSS) Data Release 14 (DR14). The sample includes the first two years of observations by the SDSS-IV extended Baryon Oscillation Spectroscopic Survey (eBOSS), providing new quasars and re-observations of BOSS quasars for improved statistical precision. Statistics are further improved by including Lyα absorption occurring in the Lyβ wavelength band of the spectra. From the measured BAO peak position along and across the line of sight, we determined the Hubble distance DH and the comoving angular diameter distance DM relative to the sound horizon at the drag epoch rd: DH(z = 2.35)/rd = 9.20 ± 0.36 and DM(z = 2.35)/rd = 36.3 ± 1.8. These results are consistent at 1.5σ with the prediction of the best-fit spatially-flat cosmological model with the cosmological constant reported for the Planck (2016) analysis of cosmic microwave background anisotropies. Combined with the Lyα auto-correlation measurement presented in a companion paper, the BAO measurements at z = 2.34 are within 1.7σ of the predictions of this model.
We measure the imprint of primordial baryon acoustic oscillations (BAOs) in the correlation function of Lyα absorption in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) and ...the extended BOSS (eBOSS) in Data Release 14 (DR14) of the Sloan Digital Sky Survey (SDSS)-IV. In addition to 179 965 spectra with absorption in the Lyman-α (Lyα) region, we use Lyα absorption in the Lyman-β region of 56 154 spectra for the first time. We measure the Hubble distance, DH, and the comoving angular diameter distance, DM, relative to the sound horizon at the drag epoch rd at an effective redshift z = 2.34. Using a physical model of the correlation function outside the BAO peak, we find DH(2.34)/rd = 8.86 ± 0.29 and DM(2.34)/rd = 37.41 ± 1.86, within 1σ from the flat-ΛCDM model consistent with CMB anisotropy measurements. With the addition of polynomial “broadband” terms, the results remain within one standard deviation of the CMB-inspired model. Combined with the quasar-Lyα cross-correlation measurement presented in a companion paper, the BAO measurements at z = 2.35 are within 1.7σ of the predictions of this model.
Abstract
We present a measurement of baryonic acoustic oscillations (BAOs) from Ly
α
absorption and quasars at an effective redshift
using the complete extended Baryonic Oscillation Spectroscopic ...Survey (eBOSS). The 16th and final eBOSS data release (SDSS DR16) contains all data from eBOSS and its predecessor, the Baryonic Oscillation Spectroscopic Survey (BOSS), providing 210,005 quasars with
z
q
> 2.10 that are used to measure Ly
α
absorption. We measure the BAO scale both in the autocorrelation of Ly
α
absorption and in its cross-correlation with 341,468 quasars with redshift
z
q
> 1.77. Apart from the statistical gain from new quasars and deeper observations, the main improvements over previous work come from more accurate modeling of physical and instrumental correlations and the use of new sets of mock data. Combining the BAO measurement from the auto- and cross-correlation yields the constraints of the two ratios
and
, where the error bars are statistical. These results are within 1.5
σ
of the prediction of the flat-ΛCDM cosmology of Planck (2016). The analysis code,
picca
, the catalog of the flux transmission field measurements, and the Δ
χ
2
surfaces are publicly available.
The extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 14 sample includes 80,118 luminous red galaxies (LRGs). By combining these galaxies with the high-redshift tail of the BOSS ...galaxy sample, we form a sample of LRGs at an effective redshift z = 0.72, covering an effective volume of 0.9 Gpc3. We account for spurious fluctuations caused by targeting and by redshift failures, which were validated on a set of mock catalogs. This analysis is sufficient to provide a 2.5% measurement of spherically averaged baryon acoustic oscillations (BAO), Mpc, at 2.8 of significance. Together with the recent quasar-based BAO measurement at z = 1.5 and forthcoming emission line galaxy-based measurements, this measurement demonstrates that eBOSS is fulfilling its remit of extending the range of redshifts covered by such measurements, laying the groundwork for forthcoming surveys such as the Dark Energy Spectroscopic Survey and Euclid.
We have used flux-transmission correlations in Lyα forests to measure the imprint of baryon acoustic oscillations (BAO). The study uses spectra of 157 783 quasars in the redshift range 2.1 ≤ z ≤ 3.5 ...from the Sloan Digital Sky Survey (SDSS) data release 12 (DR12). Besides the statistical improvements on our previous studies using SDSS DR9 and DR11, we have implemented numerous improvements in the analysis procedure, allowing us to construct a physical model of the correlation function and to investigate potential systematic errors in the determination of the BAO peak position. The Hubble distance, DH = c/H(z), relative to the sound horizon is DH(z = 2.33) /rd = 9.07 ± 0.31. The best-determined combination of comoving angular-diameter distance, DM, and the Hubble distance is found to be DH0.7DM0.3 /rd = 13.94 ± 0.35. This value is 1.028 ± 0.026 times the prediction of the flat-ΛCDM model consistent with the cosmic microwave background (CMB) anisotropy spectrum. The errors include marginalization over the effects of unidentified high-density absorption systems and fluctuations in ultraviolet ionizing radiation. Independently of the CMB measurements, the combination of our results and other BAO observations determine the open-ΛCDM density parameters to be ΩM = 0.296 ± 0.029, ΩΛ = 0.699 ± 0.100 and Ωk = −0.002 ± 0.119.
We present the first scientific results from the luminous red galaxy (LRG) sample of the extended Baryon Oscillation Spectroscopic Survey (eBOSS) combined with the high-redshift galaxies of the ...previous BOSS sample. We measure the small- and intermediate-scale clustering from a sample of more than 97,000 galaxies in the redshift range . We interpret these measurements in the framework of the Halo Occupation Distribution. The bias of this sample of LRGs is 2.30 0.03, with a satellite fraction of 13% 3% and a mean halo mass of . These results are consistent with expectations, demonstrating that these LRGs will be reliable tracers of large-scale structure at . The galaxy bias implies a scatter of luminosity at fixed halo mass, , of 0.19 dex. Using the clustering of massive galaxies from BOSS CMASS, BOSS LOWZ, and SDSS, we find that is consistent with observations over the full redshift range that these samples cover. The addition of eBOSS to previous surveys allows the investigation of the evolution of massive galaxies over the past ∼7 Gyr.
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