Baryon acoustic oscillations in the Lyα forest of BOSS DR11 quasars?

Timothée Delubac, Julian E. Bautista, Nicolás G. Busca, James Rich, David Kirkby, Stephen Bailey, Andreu Font-Ribera, Anže Slosar, Khee Gan Lee, Matthew M. Pieri, Jean Christophe Hamilton, Éric Aubourg, Michael Blomqvist, Jo Bovy, Jon Brinkmann, William Carithers, Kyle S. Dawson, Daniel J. Eisenstein, Satya Gontcho A. Gontcho, Jean Paul KneibJean Marc Le Goff, Daniel Margala, Jordi Miralda-Escudé, Adam D. Myers, Robert C. Nichol, Pasquier Noterdaeme, Ross O'Connell, Matthew D. Olmstead, Nathalie Palanque-Delabrouille, Isabelle Pâris, Patrick Petitjean, Nicholas P. Ross, Graziano Rossi, David J. Schlegel, Donald P. Schneider, David H. Weinberg, Christophe Yèche, Donald G. York

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Abstract

We report a detection of the baryon acoustic oscillation (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)-1.2+2.8(2σ) and DH/rd = 9.18 ± 0.28(1σ) ± 0.6(2σ) where DH = c/H. The optimal combination, ∼DH0.7 DA0.3/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.

Original languageEnglish (US)
JournalAstronomy and Astrophysics
Volume574
DOIs
StatePublished - Feb 1 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Delubac, T., Bautista, J. E., Busca, N. G., Rich, J., Kirkby, D., Bailey, S., Font-Ribera, A., Slosar, A., Lee, K. G., Pieri, M. M., Hamilton, J. C., Aubourg, É., Blomqvist, M., Bovy, J., Brinkmann, J., Carithers, W., Dawson, K. S., Eisenstein, D. J., Gontcho, S. G. A., ... York, D. G. (2015). Baryon acoustic oscillations in the Lyα forest of BOSS DR11 quasars? Astronomy and Astrophysics, 574. https://doi.org/10.1051/0004-6361/201423969