Karlsruhe 2011 – scientific programme

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GR: Fachverband Gravitation und Relativitätstheorie

GR 8: Kosmologie

GR 8.2: Talk

Thursday, March 31, 2011, 08:50–09:10, 20.40: 101

Geodesic motion of test particles in the space-time of cosmic (super)strings — •Parinya Sirimachan and Betti Hartmann — School of Engineering and Science, Jacobs University Bremen, 28759 Bremen

In this talk I will discuss test particle motion in the space-time of an Abelian-Higgs string and in comparison to that in the space-time of a (p,q)-string, which is a cosmic superstring consisting of p D-strings and q F-strings. The string solutions are solutions to Abelian-Higgs models coupled minimally to gravity and can only be given numerically. The solutions to the geodesic equation can hence also only be given numerically and can be classified according to the test particle's energy, angular momentum and momentum in the direction of the string axis. We find that massive test particles can be attracted and form bound orbits when they are very close to the core of the strings. In the case of Abelian-Higgs strings bound orbits exist only if the gauge boson mass is greater than the Higgs boson mass. This changes for (p,q)-strings which are field-theoretically described by two interacting Abelian-Higgs models. The fact that the p D-strings and the q F-strings form bound states allows for bound orbits of massive test particles for Higgs boson mass larger than gauge boson mass. For both cases, massless test particles can only move on escape orbits. The influence of the string parameters on observable phenomena such as the light deflection and the perihelion shift are also discussed.