arXiv:astro-ph/9307036·v2·Astrophysics
Peculiar Velocity, Cosmic Perturbation Theory and the CMB Anisotropy
Marco Bruni (School of Mathematical Sciences, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, UK., and Dipartimento di Astronomia, Università degli Studi di Trieste, via Tiepolo 11, 34131 Trieste, Italy)🇬🇧 · David H. Lyth (School of Physics and Materials, Lancaster University, Lancaster LA1 4YB, UK.)🇬🇧
Abstract
This is a somewhat extended version of the original July 93 report. It is proved that the cosmological density perturbation is associated with a peculiar velocity field. This allows a simple formulation of cosmological perturbation theory, which works entirely with quasi-Newtonian fluid flow equations. As an illustration, the large scale cosmic microwave background anisotropy (Sachs-Wolfe effect) is calculated without any reference to the metric perturbation. In addition, assuming the usual adiabatic initial condition on the density perturbation, we show that the dipole of the anisotropy measures our peculiar velocity relative to the average peculiar velocity within the last scattering surface of the microwave background, thus defining its frame of reference.
Comments: 9 pages, REVTEX, LANCS 9321