TY - JOUR

T1 - Precessional instability in binary black holes with aligned spins

AU - Gerosa, Davide

AU - Kesden, Michael

AU - O'Shaughnessy, Richard

AU - Klein, Antoine

AU - Berti, Emanuele

AU - Sperhake, Ulrich

AU - Trifirò, Daniele

PY - 2015/10/2

Y1 - 2015/10/2

N2 - Binary black holes on quasicircular orbits with spins aligned with their orbital angular momentum have been test beds for analytic and numerical relativity for decades, not least because symmetry ensures that such configurations are equilibrium solutions to the spin-precession equations. In this work, we show that these solutions can be unstable when the spin of the higher-mass black hole is aligned with the orbital angular momentum and the spin of the lower-mass black hole is antialigned. Spins in these configurations are unstable to precession to large misalignment when the binary separation r is between the values ru d ±=(√{χ1 }±√{q χ2 })4(1 -q )-2M , where M is the total mass, q ≡m2/m1 is the mass ratio, and χ1 (χ2) is the dimensionless spin of the more (less) massive black hole. This instability exists for a wide range of spin magnitudes and mass ratios and can occur in the strong-field regime near the merger. We describe the origin and nature of the instability using recently developed analytical techniques to characterize fully generic spin precession. This instability provides a channel to circumvent astrophysical spin alignment at large binary separations, allowing significant spin precession prior to merger affecting both gravitational-wave and electromagnetic signatures of stellar-mass and supermassive binary black holes.

AB - Binary black holes on quasicircular orbits with spins aligned with their orbital angular momentum have been test beds for analytic and numerical relativity for decades, not least because symmetry ensures that such configurations are equilibrium solutions to the spin-precession equations. In this work, we show that these solutions can be unstable when the spin of the higher-mass black hole is aligned with the orbital angular momentum and the spin of the lower-mass black hole is antialigned. Spins in these configurations are unstable to precession to large misalignment when the binary separation r is between the values ru d ±=(√{χ1 }±√{q χ2 })4(1 -q )-2M , where M is the total mass, q ≡m2/m1 is the mass ratio, and χ1 (χ2) is the dimensionless spin of the more (less) massive black hole. This instability exists for a wide range of spin magnitudes and mass ratios and can occur in the strong-field regime near the merger. We describe the origin and nature of the instability using recently developed analytical techniques to characterize fully generic spin precession. This instability provides a channel to circumvent astrophysical spin alignment at large binary separations, allowing significant spin precession prior to merger affecting both gravitational-wave and electromagnetic signatures of stellar-mass and supermassive binary black holes.

U2 - 10.1103/PhysRevLett.115.141102

DO - 10.1103/PhysRevLett.115.141102

M3 - Article

SN - 0031-9007

VL - 115

JO - Physical Review Letters

JF - Physical Review Letters

IS - 14

M1 - 141102

ER -