Related Links:Non-linear P(k) correlations |
Baryonic signatures in large-scale structureAcoustic oscillations in the photon-baryon fluid before last scattering imprinted similar oscillations on the present-day matter power spectrum. For currently acceptable values of the cosmological and baryon densities, the oscillations modulate the power by up to about 10%, with a 'period' in spatial wavenumber which is close to &Delta k = 0.05 Mpc-1. Non-linear evolution erases the features for modes with k > 0.2 h Mpc-1. At larger scales, the features evolve as expected from second-order perturbation theory: the visibility of the oscillations is affected only weakly by non-linear evolution. Galaxy surveys like the Sloan Digital Sky Survey are predicted to be capable of detecting the oscillatory features in the power spectrum if baryons comprise more than 15% of the total mass density of the Universe. The first acoustic peak has been detected in the Luminous Red Galaxy sample of the Sloan (Eisenstein et al., 2005, ApJ, 633, 560). |