Conical Spacetime Research Articles

Effects of curvature couplings for quantum fields on cosmic-string space-times.

The effect of $\ensuremath{\xi}R$ curvature coupling terms in the equation of motion of a massless scalar field are considered on a cosmic-string background. Realistic two- and four-dimensional models of a string, where the space-time curvature is spread over a region of nonzero size ${r}_{0}$, are constructed. In two and four dimensions, the nonzero $\ensuremath{\xi}$ term modifies the behavior within a region centered about the string, whose radius is proportional to ${r}_{0}$; however, the constant of proportionality may be exponentially large. For the standard idealized string (a conical space-time) which has no intrinsic length scale, the effects of nonzero $\ensuremath{\xi}$ do not appear.

Geodesics in spacetimes containing cosmic strings

A systematic study of geodesics in spacetimes containing cosmic strings is presented. Different models of spacetime of a single string as well as models of asymptotically conical spacetimes describing isolated matter systems pierced by cosmic strings are studied. Geodesics in the flat conical, conical Schwarzschild and Lense-Thirring spacetimes are described in detail. The problem of two-body motion in the presence of a cosmic string is also discussed. Many new kinematical effects arising from the conical structure of spacetime are found.

Gravitational Aharonov-Bohm radiation in string-generated conical space-time

The scalar, electromagnetic, and gravitational radiation in conical space-time generated by an infinite straight cosmic string is considered. It is shown that freely moving particles in conical space emit radiation. Though there is no local force acting upon particles, radiation arises due to the topological properties of space-time and it can be interpreted as the radiative gravitational Aharonov-Bohm effect. The string-modified magnetobremsstrahlung is also discussed.

Exact calculation of the Doppler shift produced by cosmic strings

The conical spacetime surrounding a straight cosmic string is described. An exact expression is derived for the Doppler shift produced by the transverse motion of a string located between a source of light and a certain observer. The equation found reduces to the usual expression in the limit gamma approximately 1. The discontinuity in the 3 K background microwave radiation induced by string motion is also discussed.