Baryon acoustic oscillations in the Ly<i>α</i>forest of BOSS DR11 quasars

Timothée Delubac(Commissariat à l'Énergie Atomique et aux Énergies Alternatives), Julian Bautista(Centre National de la Recherche Scientifique), Nicolás G. Busca(Centre National de la Recherche Scientifique), James Rich(Commissariat à l'Énergie Atomique et aux Énergies Alternatives), D. Kirkby(University of California, Irvine), S. Bailey(Lawrence Berkeley National Laboratory), Andreu Font-Ribera(Lawrence Berkeley National Laboratory), Anže Slosar(Brookhaven National Laboratory), Khee‐Gan Lee(Max Planck Institute for Astronomy), Matthew M. Pieri(University of Portsmouth), J.–Ch. Hamilton(Centre National de la Recherche Scientifique), É. Aubourg(Centre National de la Recherche Scientifique), Michael Blomqvist(University of California, Irvine), Jo Bovy(Institute for Advanced Study), J. Brinkmann, W. Carithers(Lawrence Berkeley National Laboratory), Kyle Dawson(University of Utah), Daniel J. Eisenstein(Harvard University), Satya Gontcho A Gontcho(Universitat de Barcelona), Jean‐Paul Kneib(Centre National de la Recherche Scientifique), Jean-Marc Le Goff(Commissariat à l'Énergie Atomique et aux Énergies Alternatives), Daniel Margala(University of California, Irvine), Jordi Miralda‐Escudé(Institució Catalana de Recerca i Estudis Avançats), Adam D. Myers(University of Wyoming), Robert C. Nichol(University of Portsmouth), P. Noterdaeme(Centre National de la Recherche Scientifique), Ross O’Connell(Carnegie Mellon University), Matthew D. Olmstead(University of Utah), N. Palanque‐Delabrouille(Commissariat à l'Énergie Atomique et aux Énergies Alternatives), Isabelle Pâris(Centre National de la Recherche Scientifique), Patrick Petitjean(Centre National de la Recherche Scientifique), Nicholas P. Ross(Lawrence Berkeley National Laboratory), Graziano Rossi(Commissariat à l'Énergie Atomique et aux Énergies Alternatives), David J. Schlegel(Lawrence Berkeley National Laboratory), Donald P. Schneider(Pennsylvania State University), David H. Weinberg(The Ohio State University), Christophe Yèche(Commissariat à l'Énergie Atomique et aux Énergies Alternatives), Donald G. York(Fermi National Accelerator Laboratory)
Astronomy and Astrophysics
November 12, 2014
10.1051/0004-6361/201423969
Cited by 877Open Access
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Abstract

We report a detection of the baryon acousticoscillation (BAO) feature in the flux-correlation function of the Lyα forest of high-redshift quasars with a statistical significance of five standard deviations. The study uses 137 562 quasars in the redshift range 2.1 ≤ z ≤ 3.5 from the data release 11 (DR11) of the Baryon Oscillation Spectroscopic Survey (BOSS) of SDSS-III. This sample contains three times the number of quasars used in previous studies. The measured position of the BAO peak determines the angular distance, DA(z = 2.34) and expansion rate, H(z = 2.34), both on a scale set by the sound horizon at the drag epoch, rd. We find DA/rd = 11.28 ± 0.65(1σ)+2.8-1.2 (2σ) and DH/rd = 9.18 ± 0.28(1σ) ± 0.6(2σ) where DH = c/H. The optimal combination, ~DH0.7DA0.3/rd is determined with a precision of ~2%. For the value rd = 147.4 Mpc, consistent with the cosmic microwave background power spectrum measured by Planck, we find DA(z = 2.34) = 1662 ± 96(1σ) Mpc and H(z = 2.34) = 222 ± 7(1σ) km s-1 Mpc-1. Tests with mock catalogs and variations of our analysis procedure have revealed no systematic uncertainties comparable to our statistical errors. Our results agree with the previously reported BAO measurement at the same redshift using the quasar-Lyα forest cross-correlation. The autocorrelation and cross-correlation approaches are complementary because of the quite different impact of redshift-space distortion on the two measurements. The combined constraints from the two correlation functions imply values of DA/rd that are 7% lower and 7% higher for DH/rd than the predictions of a flat ΛCDM cosmological model with the best-fit Planck parameters. With our estimated statistical errors, the significance of this discrepancy is ≈2.5σ.

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