The Lyman-α forest in three dimensions: Measurements of large scale UX correlations from BOSS 1st-year data

Aňze Slosar, Andreu Font-Ribera, Matthew M. Pieri, James Rich, Jean Marc Le Goff, Eric Aubourg, Jon Brinkmann, Nicolas Busca, Bill Carithers, Romain Charlassier, Marina Cor̂es, Rupert Croft, Kyle S. Dawson, Daniel Eisenstein, Jean Christophe Hamilton, Shirley Ho, Khee Gan Lee, Robert Lupton, Patrick McDonald, Bumbarija MedolinDemitri Muna, Jordi Miralda-Escudé, Adam D. Myers, Robert C. Nichol, Nathalie Palanque-Delabrouille, Isabelle Pris, Patrick Petitjean, Yodovina Pǐskur, Emmanuel Rollinde, Nicholas P. Ross, David J. Schlegel, Donald P. Schneider, Erin Sheldon, Benjamin A. Weaver, David H. Weinberg, Christophe Yeche, Donald G. York

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126 Scopus citations


Using a sample of approximately 14,000 z > 2.1 quasars observed in the first year of the Baryon Oscillation Spectroscopic Survey (BOSS), we measure the three-dimensional correlation function of absorption in the Lyman-α forest. The angle-averaged correlation function of transmitted flux (F = e ) is securely detected out to comoving separations of 60 h -1Mpc, the first detection of flux correlations across widely separated sightlines. A quadrupole distortion of the redshift-space correlation function by peculiar velocities, the signature of the gravitational instability origin of structure in the Lyman-α forest, is also detected at high significance. We obtain a good fit to the data assuming linear theory redshift-space distortion and linear bias of the transmitted flux, relative to the matter fluctuations of a standard ΛCDM cosmological model (inflationary cold dark matter with a cosmological constant). At 95% confidence, we find a linear bias parameter 0.16 < b < 0.24 and redshift-distortion parameter 0.44 < β < 1.20, at central redshift z = 2.25, with a well constrained combination b(1+β) = 0.3360.012. The errors on β are asymmetric, with β = 0 excluded at over 5σ confidence level. The value of β is somewhat low compared to theoretical predictions, and our tests on synthetic data suggest that it is depressed (relative to expectations for the Lyman-α forest alone) by the presence of high column density systems and metal line absorption. These results set the stage for cosmological parameter determinations from three-dimensional structure in the Lyman-α forest, including anticipated constraints on dark energy from baryon acoustic oscillations.

Original languageEnglish (US)
Article number001
JournalJournal of Cosmology and Astroparticle Physics
Issue number9
StatePublished - Sep 2011

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics


  • Lyman alpha forest
  • baryon acoustic oscillations
  • cosmic web


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