Nonlinear Effects in the Amplitude of Cosmological Density Fluctuations

Abstract

The amplitude of cosmological density fluctuations, sigma_8, 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 sigma_8 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 from the CMB because of nonlinear evolution at later times. We discuss the past and future evolution of linear and nonlinear perturbations, derive corrections to the value of sigma_8 and compare amplitudes after accounting for these differences.

9 pages, 4 figures, 1 table. Accepted for publication in JCAP

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Cited by in corpus (21)

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• Cosmic Flows on 100 Mpc/h Scales: Standardized Minimum Variance Bulk Flow, Shear and Octupole Moments
• The darkness that shaped the void: dark energy and cosmic voids
• The growth rate of cosmic structure from peculiar velocities at low and high redshifts
• Joint analysis of 6dFGS and SDSS peculiar velocities for the growth rate of cosmic structure and tests of gravity
• Cosmic flows in the nearby Universe: new peculiar velocities from SNe and cosmological constraints
• Precision cosmology with voids in the final BOSS data
• Hierarchical clustering in chameleon $f(R)$ gravity
• Peculiar-velocity cosmology with Types Ia and II supernovae
• A local measurement of the growth rate from peculiar velocities and galaxy clustering correlations in the 6dF Galaxy Survey
• Encircling the dark: constraining dark energy via cosmic density in spheres
• The homogeneity scale and the growth rate of cosmic structures
• Detected fluctuations in SDSS LRG magnitudes: Bulk flow signature or systematic?
• Galaxy Peculiar Velocities From Large-Scale Supernova Surveys as a Dark Energy Probe
• The Peculiar Velocity Correlation Function
• Measuring the matter fluctuations in the Local Universe with the ALFALFA catalog
• The Planck SZ Cluster Catalog: Expected X-ray Properties
• Anomalous anisotropic cross-correlations between WMAP CMB maps and SDSS galaxy distribution and implications on the dark flow scenario
• The Velocity Field Olympics: Assessing velocity field reconstructions with direct distance tracers
• $S_8$ from peculiar velocities: agreement with Planck for Tully--Fisher and supernovae, tension for the fundamental plane