The Lyman-α Forest Power Spectrum from the Sloan Digital Sky Survey

We measure the power spectrum, PF (k, z), of the transmitted flux in the Lyα forest using 3035 high redshift quasar spectra from the Sloan Digital Sky Survey. This sample is almost two orders of magnitude larger than any previously available data set, yielding statistical errors of ∼ 0.6% and ∼ 0.005 on, respectively, the overall amplitude and logarithmic slope of PF (k, z). This unprecedented statistical power requires a correspondingly careful analysis of the data and of possible systematic contaminations in it. For this purpose we reanalyze the raw spectra to make use of information not preserved by the standard pipeline. We investigate the details of the noise in the data, resolution of the spectrograph, sky subtraction, quasar continuum, and metal absorption. We find that background sources such as metals contribute significantly to the total power and have to be subtracted properly. We also find clear evidence for SiIII correlations with the Lyα forest and suggest a simple model to account for this contribution to the power. While it is likely that our newly developed analysis technique does not eliminate all systematic errors in the PF (k, z) measurement below the level of the statistical errors, our tests indicate that any residual systematics in the analysis are unlikely to affect the inference of cosmological parameters from PF (k, z). These results should provide an essential ingredient for all future attempts to constrain modeling of structure formation, cosmological parameters, and theories for the origin of primordial fluctuations. Physics Department, Princeton University, Princeton, NJ 08544, USA; pm,[email protected] Physics Department, MIT, 77 Massachusetts Av., Cambridge MA 02139, USA Princeton University Observatory, Princeton, NJ 08544, USA Department of Astronomy, Ohio State University, Columbus, OH 43210, USA School of Natural Sciences, Institute for Advanced Study, Einstein Drive, Princeton NJ 08540, USA Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802,