Lensing Properties of Lightlike Current Carrying Cosmic Strings

TL;DR

This paper investigates how lightlike currents on superconducting cosmic strings affect their gravitational lensing properties, revealing dynamic double images that evolve with the passing current pulse, with implications for cosmic string detection.

Contribution

It models the full spacetime metric of superconducting cosmic strings with lightlike currents, extending previous static models to include dynamic current pulses and their observational signatures.

Findings

Double image due to deficit angle evolves with current pulse

Full metric is a Taub-Kerr-Shild generalization of static string

Dynamic lensing signatures could aid cosmic string detection

Abstract

The lensing properties of superconducting cosmic strings endowed with a time dependent pulse of lightlike current are investigated. The metric outside the core of the string belongs to the $pp$--wave class, with a deficit angle. We study the field theoretic bosonic Witten model coupled to gravity, and we show that the full metric (both outside and inside the core) is a Taub-Kerr-Shild generalization of that for the static string with no current. It is shown that the double image due to the deficit angle evolves in an unambiguous way as a pulse of lightlike current passes between the source and the observer. Observational consequences of this signature of the existence of cosmic strings are briefly discussed.