The one-dimensional Lyα forest power spectrum from BOSS^⋆

¹ CEA, Centre de Saclay, Irfu/SPP, 91191 Gif-sur-Yvette, France
e-mail: nathalie.palanque-delabrouille@cea.fr
² INAF, Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131 Trieste, Italy
³ INFN/National Institute for Nuclear Physics, via Valerio 2, 34127 Trieste, Italy
⁴ APC, Université Paris Diderot-Paris 7, CNRS/IN2P3, CEA, Observatoire de Paris, 10 rue A. Domon & L. Duquet, 75205 Paris, France
⁵ Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
⁶ Bruce and Astrid McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh, PA 15213, USA
⁷ Department of Physics and Astronomy, University of Utah, 115 S 1400 E, Salt Lake City, UT 84112, USA
⁸ Institute of Theoretical Physics, University of Zurich, 8057 Zurich, Switzerland
⁹ Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
¹⁰ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹¹ Institució Catalana de Recerca i Estudis Avançats, Barcelona, Catalonia
¹² Institut de Ciències del Cosmos, Universitat de Barcelona/IEEC, Barcelona 08028, Catalonia
¹³ Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA
¹⁴ Université Paris 6 et CNRS, Institut d’Astrophysique de Paris, 98bis Bd. Arago, 75014 Paris, France
¹⁵ Departamento de Astronomía, Universidad de Chile, 36-D Casilla, Santiago, Chile
¹⁶ Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK
¹⁷ Brookhaven National Laboratory, Bldg 510, Upton, NY 11973, USA
¹⁸ Department of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210, USA
¹⁹ School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
²⁰ Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA
²¹ Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802, USA
²² Department of Astronomy, Ohio State University, Columbus, OH, 43210, USA

Received: 24 June 2013
Accepted: 5 September 2013

Abstract

We have developed two independent methods for measuring the one-dimensional power spectrum of the transmitted flux in the Lyman-α forest. The first method is based on a Fourier transform and the second on a maximum-likelihood estimator. The two methods are independent and have different systematic uncertainties. Determination of the noise level in the data spectra was subject to a new treatment, because of its significant impact on the derived power spectrum. We applied the two methods to 13 821 quasar spectra from SDSS-III/BOSS DR9 selected from a larger sample of over 60 000 spectra on the basis of their high quality, high signal-to-noise ratio (S/N), and good spectral resolution. The power spectra measured using either approach are in good agreement over all twelve redshift bins from ⟨z⟩ = 2.2 to ⟨z⟩ = 4.4, and scales from 0.001 km s^-1 to 0.02 km s^-1. We determined the methodological andinstrumental systematic uncertainties of our measurements. We provide a preliminary cosmological interpretation of our measurements using available hydrodynamical simulations. The improvement in precision over previously published results from SDSS is a factor 2–3 for constraints on relevant cosmological parameters. For a ΛCDM model and using a constraint on H₀ that encompasses measurements based on the local distance ladder and on CMB anisotropies, we infer σ₈ = 0.83 ± 0.03 and n_s = 0.97 ± 0.02 based on H i absorption in the range 2.1 < z < 3.7.