Electromagnetic Cascades and Cascade Nucleosynthesis in the Early Universe
Abstract
We describe a calculation of electromagnetic cascading in radiation and matter in the early universe initiated by the decay of massive particles or by some other process. We have used a combination of Monte Carlo and numerical techniques which enables us to use exact cross sections, where known, for all the relevant processes. In cascades initiated after the epoch of big bang nucleosynthesis -rays in the cascades will photodisintegrate He, producing He and deuterium. Using the observed He and deuterium abundances we are able to place constraints on the cascade energy deposition as a function of cosmic time. In the case of the decay of massive primordial particles, we place limits on the density of massive primordial particles as a function of their mean decay time, and on the expected intensity of decay neutrinos.
Cite
@article{arxiv.astro-ph/9409004,
title = {Electromagnetic Cascades and Cascade Nucleosynthesis in the Early Universe},
author = {R. J. Protheroe and T. Stanev and V. S. Berezinsky},
journal= {arXiv preprint arXiv:astro-ph/9409004},
year = {2011}
}
Comments
compressed and uuencoded postscript. We now include a comparison with previous work of the photon spectrum in the cascade and the limits we calculate for the density of massive particles. The method of calculation of photon spectra at low energies has been improved. Most figures are revised. Our conclusions are substantially unchanged