Gravitational particle production during cosmic-string formation in the sudden approximation

Details Gravitational particle production during cosmic-string formation in the sudden approximation Gravitational particle production during cosmic-string formation in the sudden approximation

Jul 1989

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1989phrvd..40..282m&link_type=abstract

Physical Review D (Particles and Fields), Volume 40, Issue 2, 15 July 1989, pp.282-289

Physics

17

Particle-Theory And Field-Theory Models Of The Early Universe

Scientific paper

The production of particles due to the changing gravitational field during formation of cosmic strings is studied in the sudden approximation for massless scalar fields with arbitrary curvature coupling. A family of continuous spacetimes which describe sudden cosmic-string formation is constructed by joining together an initial spacetime and a final conical, cosmic-string spacetime along a spacelike hypersurface. Two initial spacetimes are examined: Minkowski space and the steady-state portion of de Sitter space. In the Minkowski case, it is possible to match the induced three-metrics on a one-parameter family of spacelike hypersurfaces. We find that, as the matching surface is varied, the particle production ranges from zero to a maximum which is linearly proportional to α (where α is the deficit angle of the string). Over a broad domain of matching surfaces, the particle production is proportional to α2, in agreement with the earlier calculation of Parker. The amount of particle production thus seems to be significantly sensitive to the details of the model of the formation process. In the initially de Sitter case (which would model strings forming at the end of inflation) only one matching seems possible, and the particle production is found to be linearly proportional to α. Since α is small (typically α~=8π×10-6 for grand-unified-theory strings) the particle production (and created energy density) in this case is significantly larger than earlier estimates. Some general issues concerning the implementation of the sudden approximation in curved spacetimes are also considered.

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