Simone Dall'Osso, Elena M. Rossi
As we observe in the moon-earth system, tidal interactions in binaries can lead to angular momentum exchange. The presence of viscosity is generally regarded as the condition for such transfer to happen. In this paper, we how a dynamical mechanism can cause a persistent torque between the binary components, even for inviscid bodies. This preferentially occurs at the final stage of coalescence of compact binaries, when the orbit shrinks by gravitational waves on a timescale shorter than the viscous timescale. The total orbital energy transferred to the secondary is a few 10^(-3) of its binding energy. We further show that this persistent torque induces a differentially rotating quadrupolar perturbation. Specializing to the case of a neutron star, we find that the free energy associated with this non-equilibrium state can be at least ~ 5 \times 10^(46) erg just prior to coalescence. This energy is likely stored in internal fluid motions, with a sizable amount of differential rotation. Thus, a preexisting magnetic field could be substantially amplified, up to a few \times 10^(14) Gauss.
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http://arxiv.org/abs/1203.3440
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