The antikick strikes back: Recoil velocities for nearly extremal binary black hole mergers in the test-mass limit

Abstract

Gravitational waves emitted from a generic binary black-hole merger carry away linear momentum anisotropically, resulting in a gravitational recoil, or "kick", of the center of mass. For certain merger configurations the time evolution of the magnitude of the kick velocity has a local maximum followed by a sudden drop. Perturbative studies of this "antikick" in a limited range of black hole spins have found that the antikick decreases for retrograde orbits as a function of negative spin. We analyze this problem using a recently developed code to evolve gravitational perturbations from a point-particle in Kerr spacetime driven by an effective-one-body resummed radiation reaction force at linear order in the mass ratio ν 1. Extending previous studies to nearly-extremal negative spins, we find that the well-known decrease of the antikick is overturned and, instead of approaching zero, the antikick increases again to reach ∆v/(cν 2 ) = 3.37 × 10 −3 for dimensionless spinâ = −0.9999. The corresponding final kick velocity is v end /(cν 2 ) = 0.076. This result is connected to the nonadiabatic character of the emission of linear momentum during the plunge. We interpret it analytically by means of the quality factor of the flux to capture quantitatively the main properties of the kick velocity. The use of such quality factor does not require trajectories nor horizon curvature distributions and should therefore be useful both in perturbation theory and numerical relativity.

Factorization and resummation: A new paradigm to improve gravitational wave amplitudes. III. The spinning test-body terms

“…The delta functions in the source can be discretized either using a narrow Gaussian or discrete delta functions; the former option is used in case of circular orbits as discussed in [17]. The code was extensively tested and delivers multipolar waveforms and GW fluxes at null infinity with an accuracy well below the 1% level up to m = 4 modes [15][16][17]39]. The data used for this work are produced exactly as described in [16,17].…”

Asymptotic gravitational wave fluxes from a spinning particle in circular equatorial orbits around a rotating black hole

“…In this Section we review our approach to solve the TE in the time domain by means of the Teukode (see [60][61][62] for further details). We discuss a strategy of computing the source term of the TE for a pole-dipole particle.…”

Fast plunges into Kerr black holes

“…Global SL(2, R) conformal symmetry and local Virasoro conformal symmetry have been utilized recently in [11] and [12] to calculate the corresponding emitted gravitational waves during a near-ISCO circular orbit and the post-ISCO plunge, respectively. The analysis was entirely analytic -see [15,16] for recent and compatible numerical analyses of this problem. 1 Despite the fact that radiation reaction circularizes trajectories rather efficiently, most astrophysical relevant EMRIs are expected to have such large initial eccentricities that more than 50% of all observable EMRIs will end with plunges from a moderately eccentric last stable orbit [20].…”