Abstract
We present a measurement of the baryon acoustic oscillation (BAO) scale at redshiftz = 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 Lyαabsorption occurring in the Lyβwavelength band of the spectra. From the measured BAO peak position along and across the line of sight, we determined the Hubble distanceDHand the comoving angular diameter distanceDMrelative to the sound horizon at the drag epochrd:DH(z = 2.35)/rd = 9.20 ± 0.36 andDM(z = 2.35)/rd = 36.3 ± 1.8. These results are consistent at 1.5σwith the prediction of the best-fit spatially-flat cosmological model with the cosmological constant reported for thePlanck(2016) analysis of cosmic microwave background anisotropies. Combined with the Lyαauto-correlation measurement presented in a companion paper, the BAO measurements atz = 2.34 are within 1.7σof the predictions of this model.
Highlights
The baryon acoustic oscillation (BAO) peak in the cosmological matter correlation function at a distance corresponding to the sound horizon, rd ∼ 100 h−1 Mpc, has been seen at several redshifts using a variety of tracers
BAO measurements have found an important role in testing the robustness of the spatially-flat cosmology with cold dark matter and the cosmological constant (ΛCDM) that is consistent with observed cosmic microwave background (CMB) anisotropies (Planck Collaboration XIII 2016)
For the purposes of the measurement of the correlation function, all pixels in the DLA where the transmission is less than 20% are masked and the absorption in the wings is corrected using a Voigt profile following the procedure of Lee et al (2013)
Summary
The baryon acoustic oscillation (BAO) peak in the cosmological matter correlation function at a distance corresponding to the sound horizon, rd ∼ 100 h−1 Mpc, has been seen at several redshifts using a variety of tracers. We update this analysis with new quasars and forests from the SDSS Data Release 14 (DR14; Abolfathi et al 2018; Pâris et al 2018) obtained in the extended Baryon Oscillation Spectroscopy Survey (eBOSS) program (Dawson et al 2016) of SDSS-IV (Blanton et al 2017) This data set has been previously used to measure the cross-correlation between quasars and the flux in the “CIV forest” due to absorption by triply-ionized carbon (Blomqvist et al 2018). The measurements presented in this paper were made using the publicly available Python package picca developed by our team
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