The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: first measurement of baryon acoustic oscillations between redshift 0.8 and 2.2

Abstract

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 2.8σ. We determine the spherically averaged BAO distance to z = 1.52 to 3.8 per cent precision: D V (z = 1.52) = 3843 ± 147 (r d /r d,fid ) 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 ΛCDM 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 Ω Λ > 0 at 6.6σ significance when testing a ΛCDM model with free curvature.

The SDSS-IV Extended Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations at Redshift of 0.72 with the DR14 Luminous Red Galaxy Sample

“…The larger error of our measurement compared to the forecast might also be due to statistical fluctuations, since the distribution of estimated errors has a large dispersion, as observed with mock catalogs in Figure 10. Previous BAO measurements (e.g., Alam et al 2017;Ata et al 2018) typically also report estimated errors that are larger than predictions. …”

“…Mock catalogs were created with the quick particle mesh (QPM) method (White et al 2014), also used in recent clustering studies (Alam et al 2017;Ata et al 2018). Each realization consists of a different set of second-order Lagrangian perturbation theory (2LPT) initial conditions computed at z=25.…”

“…To fit the measured correlation function, we follow the standard approach described in previous papers (e.g., Alam et al 2017;Ata et al 2018). The model redshift-space correlation function is obtained from a Fourier transform of the power spectrum, which is defined as …”

LyaCoLoRe: synthetic datasets for current and future Lyman-α forest BAO surveys

“…This would involve using the entire data reduction pipeline -including continuum fitting and the use of a distortion matrix -and is beyond the scope of this work. As an approximate comparison, we observe that the size of the deviation of points in the 0.0 < r ⊥ < 4.0 bin in the right panel of Figure 6 is approximately an order of magnitude smaller than the size of the error bars in the uppermost two panels of Figure 2 of [62] 10 .…”

“…Making such an extreme cut in rest-frame wavelength greatly reduces the number of HCDs in our catalogue. In this work we use approximately 30 times the number of skewers 10 It should be noted that [62] includes only HCDs at least 5000 km/s away from their host quasar, equivalent to a rest-frame wavelength cut of approximately 1195Å. We choose to use λr,HCD < λLyα in the right panel of Figure 6 in order to explain the relationship between the geometry of the problem and the observed effect more clearly.…”