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

Abstract

We measure the imprint of primordial baryon acoustic oscillations (BAO) in the correlation function of Ly\(\alpha\) 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-\(\alpha\) (Ly\(\alpha\)) region, we use, for the first time, Ly\(\alpha\) absorption in the Lyman-\(\beta\) region of 56,154 spectra. We measure the Hubble distance, \(D_H\), and the comoving angular diameter distance, \(D_M\), relative to the sound horizon at the drag epoch \(r_d\) at an effective redshift \(z=2.34\). Using a physical model of the correlation function outside the BAO peak, we find \(D_H(2.34)/r_d=8.86\pm 0.29\) and \(D_M(2.34)/r_d=37.41\pm 1.86\), within 1\(\sigma\) from the flat-\(\Lambda\)CDM 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-Ly\(\alpha\) cross-correlation measurement presented in a companion paper Blomqvist19, the BAO measurements at \(z=2.35\) are within 1.7\(\sigma\) of the predictions of this model.