The Lyα Forest Power Spectrum from the Sloan Digital Sky Survey

Abstract

We measure the power spectrum, P F (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 P F (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 P F (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 P F (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.

Observational probes of cosmic acceleration

“…Modeling errors far too weak to show up in any one spectrum could inject correlations that bias the BAO scale or simply increase the noise far above the expected sample variance. The most detailed discussions of systematic errors in large-scale Lyα forest measurements are those of McDonald et al (2006) and Slosar et al (2011). Measuring the scale of the BAO feature again appears much easier than determining the broad-band shape or absolute amplitude of the power spectrum.…”

“…All have solar metallicity. Blueward of Lyα they have been adjusted for an IGM transmission factor of 0.8 (appropriate for z = 2.25; see McDonald et al [2006]), but other corrections (dust, nebular emission) are not included. The models are obtained from Bruzual and Charlot (2003).…”

“…However, even after marginalizing over these parameters there is enough information in the clustering statistics of the flux F to constrain the shape and amplitude of the matter power spectrum (e.g., Croft et al 2002;McDonald et al 2006). Lyα forest surveys conducted for BAO allow high precision measurements of flux correlations on smaller scales, so they have the statistical power to achieve tight constraints on matter clustering.…”

21 cm observation of large-scale structures atz ~ 1

“…Ongoing surveys, such as BOSS (Eisenstein et al 2011) or future surveys, such as LSST (Abell et al 2009), plan to measure the BAO scale precisely in the redshift range 0 z 3, using either optical observation of galaxies or 3D mapping A&A 540, A129 (2012) of Lyman α absorption lines toward distant quasars (McDonald et al 2006;McDonald & Eisenstein 2007). Radio observation of the 21 cm emission of neutral hydrogen is a very promising technique for mapping matter distribution up to redshift z ∼ 3, and it complements optical surveys, especially in the optical redshift desert range 1 z 2, and possibly up to the reionization redshift (Wyithe et al 2008).…”

SUSY SU(5)×S 4 GUT flavor model for fermion masses and mixings with adjoint, large θ 13 PMNS

“…The plot of the ratio |m 3 /m 2 | and sum of light neutrino mass k m k as function of the lightest neutrino mass m lightest , which is m 1 (m 3 ) for NH (IH) mass spectrum, are shown in figure 3(a) and figure 3(b), respectively. Note that the horizontal lines in figure 3(b) represents the cosmological bound at 0.19 eV (black), corresponding to the combined observational data from [113][114][115][116][117][118][119][120][121][122], and the upper bounds 0.23 eV from Planck [123]. The ratio tends to a degenerate mass spectrum in both cases as the value of m lightest → 0.1eV which is disfavoured in the model.…”