Professor Pedro Ferreira

Abstract:

Ultralight scalar fields, with masses of between m=10⊃-33eV and m=10⊃-22eV, can affect the growth of structure in the Universe. We identify the different regimes in the evolution of ultralight scalar fields, how they affect the expansion rate of the Universe, and how they affect the growth rate of cosmological perturbations. We find a number of interesting effects, discuss how they might arise in realistic scenarios of the early universe, and comment on how they might be observed. © 2010 The American Physical Society.

Abstract:

The peculiar motions of galaxies can be used to infer the distribution of matter in the Universe. It has recently been shown that measurements of the peculiar velocity field indicates an anomalously high bulk flow of galaxies in our local volume. In this paper we find the implications of the high bulk flow for the power spectrum of density fluctuations. We find that analyzing only the dipole moment of the velocity field yields an average power spectrum amplitude which is indeed much higher than the LCDM value. However, by also including shear and octupole moments of the velocity field, and marginalizing over possible values for the growth rate, an average power spectrum amplitude which is consistent with LCDM is recovered. We attempt to infer the shape of the matter power spectrum from moments of the velocity field, and find a slight excess of power on scales ~ h-1 Gpc.