Kinetics of small perturbations in an isotropic universe. III - Long-wave perturbations in an ultrarelativistic gas
Abstract
Consideration is given to long-wave gravitational perturbations in an isotropic expanding universe, filled with an ultrarelativistic gas. A kinetic approach in the collisionless approximation leads to the conclusion that scalar and vector perturbations, arising at a moment eta(0) much less than 1/n (where n is the wave vector and eta is the four-dimensional time coordinate), increase if the perturbation of the density of the macroscopic impulse of gas is nonzero at eta(0). This increase proceeds until the moment eta(1) = 2.7 eta(0), when the impulse density perturbation becomes zero. A solution is also obtained for tensor perturbations in the limit n eta much less than unity.
- Publication:
-
Fizika
- Pub Date:
- 1978
- Bibcode:
- 1978Fiz....21...37Z
- Keywords:
-
- Cosmic Gases;
- Density Wave Model;
- Gravity Anomalies;
- Isotropic Media;
- Perturbation Theory;
- Relativistic Plasmas;
- Collisionless Plasmas;
- Cosmology;
- Gravity Waves;
- Kinetic Theory;
- Astrophysics