Ringdown spectroscopy of rotating black holes pierced by cosmic strings

Multiple gauge theories predict the presence of cosmic strings with different mass densities G mu/c(2). We derive an equation governing the perturbations of a rotating black hole pierced by a straight, infinitely long cosmic string along its axis of rotation and calculate the quasinormal-mode frequencies of such a black hole. We then carry out parameter estimation on the first detected gravitational-wave event, GW150914, by hypothesizing that there is a string piercing through the remnant, yielding a constraint of G mu/c(2) < 3.8 x 10(-3) at the 90% confidence interval with a comparable Bayes factor with an analysis for a Kerr black hole without a string. In contrast to existing studies which focus on the mutual intersection of cosmic strings, or the cosmic string network, our work focuses on the intersection of a cosmic string with a black hole, with characteristics which can be identified in binary coalescence signals.

Automated summary

The study investigates the interaction between cosmic strings and a rotating black hole, and carries out parameter estimation using the gravitational-wave event GW150914, resulting in a constraint of the mass density of cosmic strings being less than 3.8 x 10(-3) at a 90% confidence level.