Relativistic collisionless particles and the evolution of cosmological perturbations

Abstract

view Abstract Citations (26) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Relativistic collisionless particles and the evolution of cosmological perturbations Vishniac, E. T. Abstract The paper considers the evolution of cosmological perturbations in an Einstein-de Sitter universe filled with the usual perfect gas plus a relativistic collisionless gas. On scales smaller than the horizon the collisionless gas undergoes rapid phase mixing and tends to a uniform distribution. However, on larger scales the ability of the collisionless gas to support a stress leads to altered growth rates for all perturbation modes except the nondecaying tensor and scalar modes. If the fraction of the total energy contained in the collisionless gas exceeds 5/16, then all the affected modes display oscillatory behavior. Also presented are the results of a numerical integration of the evolution of adiabatic perturbations as they cross the horizon, including the effect of massless neutrinos. The sound waves that result are lowered in amplitude by approximately 20% relative to their amplitudes in a neutrino-free cosmology. Publication: The Astrophysical Journal Pub Date: June 1982 DOI: 10.1086/160004 Bibcode: 1982ApJ...257..456V Keywords: Collisionless Plasmas; Cosmology; Perturbation Theory; Relativistic Particles; Relativity; Adiabatic Flow; Astronomical Models; Baryons; Neutrinos; Scalars; Sound Waves; Tensors; Astrophysics full text sources ADS |