Helium photodisintegration and nucleosynthesis: Implications for topological defects, high energy cosmic rays, and massive black holes
- Department of Astronomy and Astrophysics, Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637-1433 (United States)
We consider the production of {sup 3}He and {sup 2}H by {sup 4}He photodisintegration initiated by nonthermal energy releases during early cosmic epochs. We find that this process cannot be the predominant source of primordial {sup 2}H since it would result in anomalously high {sup 3}He/D ratios in conflict with standard chemical evolution assumptions. We apply this fact to constrain topological defect models of highest energy cosmic ray (HECR) production. Such models have been proposed as possible sources of ultrahigh energy particles and {gamma} rays with energies above 10{sup 20} eV. The constraints on these models derived from {sup 4}He photodisintegration are compared to corresponding limits from spectral distortions of the cosmic microwave background radiation and from the observed diffuse {gamma}-ray background. It is shown that for reasonable primary particle injection spectra superconducting cosmic strings, unlike ordinary strings or annihilating monopoles, cannot produce the HECR flux at the present epoch without violating at least the {sup 4}He-photodisintegration bound. The constraint from the diffuse {gamma}-ray background rules out the dominant production of HECR by the decay of grand unification particles in models with cosmological evolution assuming standard fragmentation functions. Constraints on massive black hole induced photodisintegration are also discussed. {copyright} 1995 The American Physical Society.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 147834
- Journal Information:
- Physical Review, D, Vol. 52, Issue 12; Other Information: PBD: 15 Dec 1995
- Country of Publication:
- United States
- Language:
- English
Similar Records
Neutralinos, big bang nucleosynthesis, and {sup 6}Liin low-metallicity stars
Electromagnetic cascades and cascade nucleosynthesis in the early Universe