- Palanque-Delabrouille, Nathalie;
- Yèche, Christophe;
- Borde, Arnaud;
- Le Goff, Jean-Marc;
- Rossi, Graziano;
- Viel, Matteo;
- Aubourg, Éric;
- Bailey, Stephen;
- Bautista, Julian;
- Blomqvist, Michael;
- Bolton, Adam;
- Bolton, James S;
- Busca, Nicolás G;
- Carithers, Bill;
- Croft, Rupert AC;
- Dawson, Kyle S;
- Delubac, Timothée;
- Font-Ribera, Andreu;
- Ho, Shirley;
- Kirkby, David;
- Lee, Khee-Gan;
- Margala, Daniel;
- Miralda-Escudé, Jordi;
- Muna, Demitri;
- Myers, Adam D;
- Noterdaeme, Pasquier;
- Pâris, Isabelle;
- Petitjean, Patrick;
- Pieri, Matthew M;
- Rich, James;
- Rollinde, Emmanuel;
- Ross, Nicholas P;
- Schlegel, David J;
- Schneider, Donald P;
- Slosar, Anže;
- Weinberg, David H
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 ns = 0.97 ± 0.02 based on Hi absorption in the range 2.1 < z < 3.7. © ESO, 2013.