Radially stabilized inflating cosmic strings
Abstract
In general relativity, local cosmic strings are well known to produce a static, locally flat spacetime with a wedge removed. If the tension exceeds a critical value, the deficit angle becomes larger than 2 π , leading to a compact exterior that ends in a conical singularity. In this paper, we investigate dynamical solutions for cosmic strings with supercritical tensions. To this end, we model the string as a cylindrical shell of finite and stabilized transverse width and show that there is a marginally supercritical regime in which the stabilization can be achieved by physically reasonable matter. We show numerically that the static deficit angle solution is unstable for supercritical string tensions. Instead, the geometry starts expanding in the axial direction at an asymptotically constant rate, and a horizon is formed in the exterior spacetime, which has the shape of a growing cigar. We are able to find the analytic form of the attractor solution describing the interior of the cosmic string. In particular, this enables us to analytically derive the relation between the string tension and the axial expansion rate. Furthermore, we show that the exterior conical singularity can be avoided for dynamical solutions. Our results might be relevant for theories with two extra dimensions, modeling our Universe as a cosmic string with a threedimensional axis. We derive the corresponding Friedmann equation, relating the onbrane Hubble parameter to the string tension or, equivalently, brane cosmological constant.
 Publication:

Physical Review D
 Pub Date:
 March 2015
 DOI:
 10.1103/PhysRevD.91.064010
 arXiv:
 arXiv:1412.2750
 Bibcode:
 2015PhRvD..91f4010N
 Keywords:

 04.25.dc;
 04.50.h;
 98.80.Cq;
 Numerical studies of critical behavior singularities and cosmic censorship;
 Higherdimensional gravity and other theories of gravity;
 Particletheory and fieldtheory models of the early Universe;
 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Theory
 EPrint:
 20 pages, 12 figures, 1 table