Charged Black Hole Mergers: Orbit Circularisation and Chirp Mass Bias

Abstract

We consider the inspiral of black holes carrying U(1) charge that is not electromagnetic, but corresponds to some dark sector. In the weak-field, lowvelocity regime, the components follow Keplerian orbits. We investigate how the orbital parameters evolve for dipole-dominated emission and find that the orbit quickly circularises, though not as efficiently as for a gravitationally dominated emission. We then regard circular orbits, and look for modifications in the gravitational waveform from the components carrying small charges. Taking this into account we populate the waveform with simplified LIGO noise and put it through a matched filtering procedure where the template bank only consists of uncharged templates, focusing on the charges' effect on the chirp mass estimation. We find a consistent overestimation of the 'generalised' chirp mass, and a possible over-and underestimation of the actual chirp mass. Finally, we briefly consider the effect of such charges on hyperbolic encounters, finding again a bias arising from interpreting the generalised chirp mass as the actual chirp mass.

Gravitational and electromagnetic radiation from binary black holes with electric and magnetic charges: Circular orbits on a cone

“…Compared to Schwarzschild black holes, charged black holes have rich phenomena. Recently, charged black holes have been discussed extensively [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]. Binary black holes with charges emit not only gravitational radiation but also electromagnetic radiation.…”

“…The Coulomb-type force due to a pure electric or magnetic charge changes the coupling parameter of the gravitational force and alters the gravitational wave emission compared to an uncharged binary, which leads to a different merger rate of primordial black hole [9]. The bias in the binary parameters due to the charge-chirp mass degeneracy is discussed in [10]. For the first merger event of binary black holes reported by LIGO/Virgo, GW150914, Ref.…”

Gravitational and electromagnetic radiation from binary black holes with electric and magnetic charges: Circular orbits on a cone

“…Then we consider the emission from magnetic charges in the same orbit and finally superimpose their fields. This derivation follows the same procedure as [35,41].…”

Eccentricity evolution of compact binaries and applications to gravitational-wave physics

“…Our results for the electromagnetic flux of energy and angular momentum agree with those in Refs. [19,20] (after a proper re-definition of charge). In the adiabatic approximation the major semi-axis and the eccentricity follow…”

“…Our results for the electromagnetic radiation emitted by a binary are in agreement with the ones of Refs. [19,20].…”