Scalar perturbations in two-temperature cosmological plasmas |
| |
Authors: | J Moortgat † M Marklund |
| |
Institution: | Department of Astrophysics, IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, the Netherlands;Department of Physics, Centre for Nonlinear Physics, UmeåUniversity, SE–901 87 Umeå, Sweden |
| |
Abstract: | We study the properties of density perturbations of a two-component plasma with a temperature difference on a homogeneous and isotropic background. For this purpose, we extend the general relativistic gauge-invariant and covariant (GIC) perturbation theory to include a multifluid with a particular equation of state (ideal gas) and imperfect fluid terms due to the relative energy flux between the two species. We derive closed sets of GIC vector and subsequently scalar evolution equations. We then investigate solutions in different regimes of interest. In particular, we study long-wavelength and arbitrary-wavelength Langmuir and ion-acoustic perturbations. The harmonic oscillations are superposed on a Jeans-type instability. We find a generalized Jeans criterion for collapse in a two-temperature plasma, which states that the species with the largest sound velocity determines the Jeans wavelength. Furthermore, we find that within the limit for gravitational collapse, initial perturbations in either the total density or charge density lead to a growth in the initial temperature difference. These results are relevant for the basic understanding of the evolution of inhomogeneities in cosmological models. |
| |
Keywords: | gravitation plasmas relativity cosmology: theory large-scale structure of Universe |
|
|