The one-dimensional Lyα forest power spectrum from BOSS
2013
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 H i absorption in the range
2.1 < z < 3.7.
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