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Paper: Cosmic Flows on 100 h-1Mpc Scales and the Non-Linear σ8
Volume: 426, Proceedings of the 2009 Snowbird Particle Astrophysics and Cosmology Workshop (SNOWPAC 2009)
Page: 158
Authors: Feldman, H. A.
Abstract: To study galactic motions on the largest available scales, we require bulk flow moments whose window functions have as narrow a peak as possible and having as small an amplitude as possible outside the peak. Typically the moments found using the maximum likelihood estimate weights do not meet these criteria. We present a new method for calculating weights for moments that essentially allow us to “design” the moment’s window function, subject, of course, to the distribution and uncertainties of the available data. The amplitude of cosmological density fluctuations, σ8, has been studied and estimated by analysing many cosmological observations. The values of the estimates vary considerably between the various probes. However, different estimators probe the value of σ8 in different cosmological scales and do not take into account the nonlinear evolution of the parameter at late times. We show that estimates of the amplitude of cosmological density fluctuations derived from cosmic flows are systematically higher than those inferred at early epochs because of nonlinear evolution at later times. Here we derive corrections to the value of σ8 and compare amplitudes after accounting for this effect.
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