Kicks in charged black hole binaries

We compute the emission of linear momentum (kicks) by both gravitational and electromagnetic radiation in fully general-relativistic numerical evolutions of quasicircular charged black hole binaries. We derive analytical expressions for slowly moving bodies and explore numerically a variety of mass ratios and charge -to-mass ratios. We find that for the equal-mass case our analytical expression is in excellent agreement with the observed values, and, contrarily to what happens in the vacuum case, we find that in the presence of electromagnetic fields there is emission of momentum by gravitational waves. We also find that the strong gravitational kicks of binaries with unequal masses affect the electromagnetic kicks, causing them to strongly deviate from Keplerian predictions. For the values of charge-to-mass ratio considered in this work, we observe that magnitudes of the electromagnetic kicks are always smaller than the gravitational ones.

Automated summary

In this study, we investigate the contributions of gravitational and electromagnetic radiation to the emission of linear momentum in quasicircular charged black hole binaries using fully general-relativistic numerical evolutions. We find that gravitational waves can emit momentum in the presence of electromagnetic fields, contrary to the vacuum case. Additionally, unequal mass binaries exhibit significant deviations of electromagnetic kicks from Keplerian predictions due to strong gravitational kicks. Moreover, the magnitudes of electromagnetic kicks are always smaller than gravitational ones for the charge-to-mass ratios considered in this work.