Measurement of baryon acoustic oscillation correlations at z = 2.3 with SDSS DR12 Ly α-Forests

Julian E. Bautista, Nicolás G. Busca, Julien Guy, James Rich, Michael Blomqvist, Hélion Du Mas Des Bourboux, Matthew M. Pieri, Andreu Font-Ribera, Stephen Bailey, Timothée Delubac, David Kirkby, Jean Marc Le Goff, Daniel Margala, AnžE Slosar, Jose Alberto Vazquez, Joel R. Brownstein, Kyle S. Dawson, Daniel J. Eisenstein, Jordi Miralda-Escudé, Pasquier NoterdaemeNathalie Palanque-Delabrouille, Isabelle Pâris, Patrick Petitjean, Nicholas P. Ross, Donald P. Schneider, David H. Weinberg, Christophe Yèche

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We have used flux-transmission correlations in Lyα forests to measure the imprint of baryon acoustic oscillations (BAO). The study uses spectra of 157 783 quasars in the redshift range 2:1 ≤ z ≤ 3:5 from the Sloan Digital Sky Survey (SDSS) data release 12 (DR12). Besides the statistical improvements on our previous studies using SDSS DR9 and DR11, we have implemented numerous improvements in the analysis procedure, allowing us to construct a physical model of the correlation function and to investigate potential systematic errors in the determination of the BAO peak position. The Hubble distance, DH = c=H(z), relative to the sound horizon is DH(z = 2:33)=rd = 9:07 ± 0:31. The best-determined combination of comoving angular-diameter distance, DM, and the Hubble distance is found to be D0:7 H D0:3 M =rd = 13:94±0:35. This value is 1:028±0:026 times the prediction of the flat-ΛCDM model consistent with the cosmic microwave background (CMB) anisotropy spectrum. The errors include marginalization over the effects of unidentified high-density absorption systems and fluctuations in ultraviolet ionizing radiation. Independently of the CMB measurements, the combination of our results and other BAO observations determine the open-ΛCDM density parameters to be ΩM = 0:296 ± 0:029, ΩΛ = 0:699 ± 0:100 and Ωk = -0:002 ± 0:119.

Original languageEnglish
Article numberA12
JournalAstronomy and Astrophysics
Early online date30 Jun 2017
Publication statusPublished - 1 Jul 2017


  • Cosmological parameters
  • Dark energy
  • RCUK
  • STFC


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