Speaker
Description
50 years after Tom Kibble’s seminal paper on cosmic strings, research on strings remains active and their GW signatures are currently being searched for by, for instance, the LVK and PTA collaborations. While much focus is on the stochastic GW background from the ensemble of cosmic strings, cosmic string loops also generate short duration GW bursts with a characteristic waveform. In this talk I will explain some of the features of these burst signals, and also point out that they are repeated, since cosmic string loops evolve quasi-periodically in time. Furthermore they will always appear from essentially the same position in the sky. These different points may help with parameter estimation (sky position, string tension…). We will estimate the number of GW repeaters for LVK and LISA, and show that the cosmic string tension that can be probed scales as detector sensitivity to the sixth power, which raises hope for detection in future GW detectors.
If time permits, I will also recall an old model for the evolution of the number density of cosmic string loops, developed by Tom, Ed Copeland and myself. We attempted to include the effects of possible loop fragmentation. This model has recently been revisited, in a different context, and I will outline some of the salient aspects of the results. After all, after 50 years, there is still a lot of disagreement over the cosmic string loop number density!