Density and graviton perturbations in the cosmic microwave background
Abstract
We evaluate and compare the gravitational wave and density perturbation contributions to the cosmic microwave background radiation on the basis of the same powerlaw inflationary model. The inflation to radiation transition is treated in this paper as instantaneous, but a model is constructed to allow for a smooth transition from the radiation to the matterdominated eras. The equations are numerically investigated and integrated, without any basic approximations being made. Use is made of the synchronous gauge, with appropriate gaugeinvariant variables, thus eliminating any confusion arising from unphysical gauge modes. We find a nonnegligible gravitational wave contribution, which becomes dominant for a powerlaw expansion with exponent q<13. We also explore the dependence of our results with the main characteristic of the transition region, its length.
 Publication:

Physical Review D
 Pub Date:
 May 1997
 DOI:
 10.1103/PhysRevD.55.5908
 arXiv:
 arXiv:astroph/9702238
 Bibcode:
 1997PhRvD..55.5908H
 Keywords:

 98.80.Cq;
 04.30.w;
 Particletheory and fieldtheory models of the early Universe;
 Gravitational waves: theory;
 Astrophysics
 EPrint:
 19 pages