A practical formula for the radiated angular momentum
Abstract
We present a simple formula for the radiated angular momentum based on a spin-weighted spherical harmonic decomposition of the Weyl scalar psi4 representing outgoing radiation in the Kinnersley tetrad. We test our formula by measuring the radiated angular momentum from three simulations of non-spinning equal-mass black-hole binary with orbital angular momentum aligned along the x, y, and z axes respectively. We find that the radiated angular momentum agrees with the differences in the remnant horizon spins and the initial angular momentum for each system.
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