Matthew Lake, Teruaki Suyama
We consider the evolution of an initially FLRW universe after the formation
of a long, straight, cosmic string with arbitrary tension and mass per unit
length. The birth of the string sources scalar and tensor-type perturbations in
the background metric and both density and velocity perturbations in the
background fluid, which compensate for the string mass and maintain energy
conservation. The former generate the deficit angle within the light cone of
the string and a gravitational shock front at the cosmological horizon, whereas
the latter are confined within the sound cone. We study the properties of the
metric within each region of the resulting spacetime and give the explicit
coordinate transformations which demonstrate non-violation of causality. This
paper generalizes the work of Magueijo, who performed a similar analysis for
the Nambu-Goto (NG) string, but the solutions given here differ from the ones
he obtained, even in the NG limit. We believe this to be a consequence of the
choice of boundary conditions for the Poisson equation and show that Magueijo's
choice is inconsistent with the trace part of the Einstein equations. However,
the general qualitative picture remains the same and the method of analysis
follows closely his original work.
View original:
http://arxiv.org/abs/1112.2478
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