Limits on Cosmological Magnetic Fields and Other Anisotropic Stresses
Abstract
We discuss the cosmological evolution of matter sources with small anisotropic pressures. This includes electric and magnetic fields, collisionless relativistic particles, gravitons, antisymmetric axion fields in low-energy string cosmologies, spatial curvature anisotropies, and stresses arising from simple topological defects. The COBE microwave sky maps are used to place strong limits on the possible contribution of these sources to the total density of the universe. We explain why the limits obtained from primordial nucleosynthesis are generally weaker than those imposed by the microwave background isotropy. The effect of inflation on all these stresses is also calculated.
Keywords
Cite
@article{arxiv.gr-qc/9712020,
title = {Limits on Cosmological Magnetic Fields and Other Anisotropic Stresses},
author = {John D. Barrow},
journal= {arXiv preprint arXiv:gr-qc/9712020},
year = {2007}
}
Comments
28 pages, Tex file, no figures. Proceedings 4th Paris Cosmology Colloquium, Paris June 1997, ed H. de Vega, and N. Sanchez