Spin flips and precession in black-hole-binary mergers

Abstract

We use the ''moving puncture'' approach to perform fully nonlinear evolutions of spinning quasicircular black-hole binaries with individual spins unaligned with the orbital angular momentum. We evolve configurations with the individual spins (parallel and equal in magnitude) pointing in the orbital plane and 45 above the orbital plane. We introduce a technique to measure the spin direction and track the precession of the spin during the merger, as well as measure the spin flip in the remnant horizon. The former configuration completes 1.75 orbits before merging, with the spin precessing by 98 and the final remnant horizon spin flipped by 72 with respect to the component spins. The latter configuration completes 2.25 orbits, with the spins precessing by 151 and the final remnant horizon spin flipped 34 with respect to the component spins. These simulations show for the first time how the spins are reoriented during the final stage of black-hole-binary mergers verifying the hypothesis of the spin-flip phenomenon.We also compute the track of the holes before merger and observe a precession of the orbital plane with frequency similar to the orbital frequency and amplitude increasing with time.

Extra-large remnant recoil velocities and spins from near-extremal-Bowen-York-spin black-hole binaries

“…Notable among these advancements are developments in mathematical relativity, including systems of PDEs and gauge choices [11,12,13], the exploration of the cosmic censorship [14,15,16,17,18], and the application of isolated horizon formulae [15,16,19,20,21,22]. These breakthroughs have also influenced the development of data analysis techniques through the matching of post-Newtonian to fully-numerical waveforms [23,24,25,26].…”

Approximate Killing vectors onS2

“…Better still, a "Killing Transport" (KT) technique [5], which finds exact Killing vectors when they are present, has been recently adopted, and appears to give physically reasonable results (cf Refs. [4,6]). Our definition is shown to be even better in a well-defined least squared sense and, for coalescing binary black holes, yields other interesting results worthy of further investigation.…”

Practical formula for the radiated angular momentum

“…We used the Linkage definition of the angular momentum to derive a formula for the radiated angular momentum (24), (14), (16) in terms of ψ 4 . The remaining radiation formulae for the energy and linear momentum have already been given in this form in Ref.…”

“…We extend the computation of the radiated angular momentum to all the three Cartesian components. These are useful to verify the conservation of the angular momentum in generic black-hole binaries, for instance, when spin precession is present [10,11,16].…”