Vol. 629
In section 3. Cosmology

Baryon acoustic oscillations at z = 2.34 from the correlations of Ly alpha absorption in eBOSS DR14

The imprint of primordial baryon acoustic oscillations (BAO) in the correlation function of Ly absorption in quasar provides an independent way of determining cosmological parameters that is based only on low-redshift measurements. The authors of this paper use Ly alpha and Ly beta spectral regions from the BOSS and eBOSS DR14 QSO data sample to study BAO. The model they have built for the Lyalpha autocorrelation function incorporates the effects of redshift space distortions, non-linear growth of matter, contamination by metals, and modeling of high-column density systems along lines of sight to quasars. The cosmological measurements obtained are in agreement with the predictions of the flat cold dark matter model favored by the measurement of cosmic microwave background anisotropies by Planck. The authors also combine the measurements of this analysis with the ones obtained from the cross-correlation of Ly alpha presented in a companion paper (Blomqvist et al. 2019), which alone would favor a value of the DH=rd ratio of 3% higher than the one favored by the Lyalpha auto-correlation. Combining the two methods, the ensemble of BAO measurements is in good agreement with the the latest Planck model, within only a 1.7 sigma difference at z=2.34.