Abstract
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.
Highlights
Since the first observations of the imprint of primordial baryonic acoustic oscillations (BAOs) as a peak in the galaxy correlation function (Eisenstein et al 2005) or as a periodic modulation in the corresponding power spectrum (Cole et al 2005), the BAO signal has led to significant constraints on cosmological parameters
An alternative tracer of the density is the intergalactic medium (IGM), itself traced by Lyα absorption in quasar spectra
We start from the CAMB linear power spectrum (Lewis et al 2000) which is decomposed into a smooth component and a peak component, following the side-band technique described by Kirkby et al (2013)
Summary
Since the first observations of the imprint of primordial baryonic acoustic oscillations (BAOs) as a peak in the galaxy correlation function (Eisenstein et al 2005) or as a periodic modulation in the corresponding power spectrum (Cole et al 2005), the BAO signal has led to significant constraints on cosmological parameters. When combined with the BAO imprint on the crosscorrelation of the Lyα forest with BOSS DR12 quasars (du Mas des Bourboux et al 2017), the values of DH/rd and DM/rd at z ∼ 2.3 differ by 2.3σ from this model. This mild tension was already present in the combined constraints of the cross-correlation measurement of Font-Ribera et al (2014) and the auto-correlation of Delubac et al (2015). We use quasar spectra from the BOSS survey and from its extended version eBOSS in the SDSS DR14 to study BAO in the Lyα auto-correlation function. The computations of the correlation functions presented in this paper have been performed using a dedicated software package: Package for Igm Cosmological-Correlations Analyses (picca), developed by our team
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
