Measurement of baryon acoustic oscillations in the Lyman-α forest fluctuations in BOSS data release 9

Anze Slosar, Vid Irsic, David Kirkby, Stephen Bailey, Nicolas G. Busca, Timothee Delubac, James Rich, Eric Aubourg, Julian E. Bautista, Vaishali Bhardwaj, Michael Blomqvist, Adam S. Bolton, Jo Bovy, Joel Brownstein, Bill Carithers, Rupert A. C. Croft, Kyle S. Dawson, Andreu Font-Ribera, J. -M. Le Goff, Shirley HoKlaus Honscheid, Khee-Gan Lee, Daniel Margala, Patrick McDonald, Bumbarija Medolin, Jordi Miralda-Escude, Adam D. Myers, Robert C. Nichol, Pasquier Noterdaeme, Nathalie Palanque-Delabrouille, Isabelle Paris, Patrick Petitjean, Matthew M. Pieri, Yodovina Piskur, Natalie A. Roe, Nicholas P. Ross, Graziano Rossi, David J. Schlegel, Donald P. Schneider, Nao Suzuki, Erin S. Sheldon, Uros Seljak, Matteo Viel, David H. Weinberg, Christophe Yeche

Research output: Contribution to journalArticlepeer-review


We use the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) to detect and measure the position of the Baryonic Acoustic Oscillation (BAO) feature in the three-dimensional correlation function in the Lyman-α flux fluctuations at a redshift zeff = 2.4. The feature is clearly detected at significance between 3 and 5 sigma (depending on the broadband model and method of error covariance matrix estimation) and is consistent with predictions of the standard ΛCDM model. We assess the biases in our method, stability of the error covariance matrix and possible systematic effects. We fit the resulting correlation function with several models that decouple the broadband and acoustic scale information. For an isotropic dilation factor, we measure 100 × (αiso − 1) = −1.6+2.0 +4.3 +7.4−2.0 −4.1 −6.8 (stat.) ±1.0 (syst.) (multiple statistical errors denote 1,2 and 3 sigma confidence limits) with respect to the acoustic scale in the fiducial cosmological model (flat ΛCDM with Ωm = 0.27, h = 0.7). When fitting separately for the radial and transversal dilation factors we find marginalised constraints 100 × (α|| − 1) = −1.3+3.5 +7.6 +12.3−3.3 −6.7 −10.2 (stat.) ±2.0 (syst.) and 100 × (α− 1) = −2.2+7.4 +17−7.1 −15 (stat.) ±3.0 (syst.). The dilation factor measurements are significantly correlated with cross-correlation coefficient of ~ −0.55. Errors become significantly non-Gaussian for deviations over 3 standard deviations from best fit value. Because of the data cuts and analysis method, these measurements give tighter constraints than a previous BAO analysis of the BOSS DR9 Lyman-α sample, providing an important consistency test of the standard cosmological model in a new redshift regime.
Original languageEnglish
Article number026
Pages (from-to)026
JournalJournal of Cosmology and Astroparticle Physics
Issue number4
Early online date10 Apr 2013
Publication statusPublished - Apr 2013


  • dark energy experiments
  • Lyman alpha forest
  • baryon acoustic oscillations


Dive into the research topics of 'Measurement of baryon acoustic oscillations in the Lyman-α forest fluctuations in BOSS data release 9'. Together they form a unique fingerprint.

Cite this