Baryon acoustic oscillations in the Lyα forest of BOSS quasars^⋆

¹ APC, Université Paris Diderot-Paris 7, CNRS/IN2P3, CEA, Observatoire de Paris, 10 rue A. Domon & L. Duquet, Paris, France
e-mail: ngbusca@apc.univ-paris7.fr
² CEA, Centre de Saclay, IRFU, 91191 Gif-sur-Yvette, France
³ Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
⁴ Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
⁵ Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK
⁶ Bldg 510 Brookhaven National Laboratory, Upton, NY 11973, USA
⁷ Apache Point Observatory, PO Box 59, Sunspot, NM 88349, USA
⁸ Department of Physics and Astronomy, University of Utah, 115 S 1400 E, Salt Lake City, UT 84112, USA
⁹ Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540, USA
¹⁰ Bruce and Astrid McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh, PA 15213, USA
¹¹ Harvard-Smithsonian Center for Astrophysics, Harvard University, 60 Garden St., Cambridge MA 02138, USA
¹² Center for Cosmology and Particle Physics, New York University, New York, NY 10003, USA
¹³ Department of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210, USA
¹⁴ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹⁵ Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706, USA
¹⁶ Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85121, USA
¹⁷ Institució Catalana de Recerca i Estudis Avançats, Barcelona, Catalonia
¹⁸ Institut de Ciències del Cosmos, Universitat de Barcelona/IEEC, 08028 Barcelona, Catalonia
¹⁹ Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA
²⁰ Université Paris 6 et CNRS, Institut d’Astrophysique de Paris, 98bis blvd. Arago, 75014 Paris, France
²¹ Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA
²² Institute for Gravitation and the Cosmos, ThePennsylvania State University, University Park, PA 16802, USA
²³ INAF, Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131 Trieste, Italy
²⁴ INFN/National Institute for Nuclear Physics, via Valerio 2, 34127 Trieste, Italy
²⁵ Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
²⁶ Department of Astronomy and Astrophysics and the Enrico Fermi Institute, The University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois, 60615, USA
²⁷ Institute of Theoretical Physics, University of Zurich, 8057 Zurich, Switzerland
²⁸ Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile

Received: 12 November 2012
Accepted: 4 February 2013

Abstract

We report a detection of the baryon acoustic oscillation (BAO) feature in the three-dimensional correlation function of the transmitted flux fraction in the Lyα forest of high-redshift quasars. The study uses 48 640 quasars in the redshift range 2.1 ≤ z ≤ 3.5 from the Baryon Oscillation Spectroscopic Survey (BOSS) of the third generation of the Sloan Digital Sky Survey (SDSS-III). At a mean redshift z = 2.3, we measure the monopole and quadrupole components of the correlation function for separations in the range 20 h^-1 Mpc < r < 200 h^-1 Mpc. A peak in the correlation function is seen at a separation equal to (1.01 ± 0.03) times the distance expected for the BAO peak within a concordance ΛCDM cosmology. This first detection of the BAO peak at high redshift, when the universe was strongly matter dominated, results in constraints on the angular diameter distance D_A and the expansion rate H at z = 2.3 that, combined with priors on H₀ and the baryon density, require the existence of dark energy. Combined with constraints derived from cosmic microwave background observations, this result implies H(z = 2.3) = (224 ± 8) km s^-1 Mpc^-1, indicating that the time derivative of the cosmological scale parameter ȧ = H(z = 2.3)/(1 + z) is significantly greater than that measured with BAO at z ~ 0.5. This demonstrates that the expansion was decelerating in the range 0.7 < z < 2.3, as expected from the matter domination during this epoch. Combined with measurements of H₀, one sees the pattern of deceleration followed by acceleration characteristic of a dark-energy dominated universe.