We use the ‘moving puncture’ approach to perform fully non-linear 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.

Publication Date



This is the pre-print of an article published by the American Physical Society. The final, published version is available here: https://doi.org/10.1103/PhysRevD.75.064030

© 2007 American Physical Society

Also archived in: arXiv:gr-qc/0612076 v4 Mar 13 2007

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus