**Authors**: Thibault Damour, Piotr Jaranowski, Gerhard Schäfer

**Date**: 6 Mar 2008

**Abstract**: Using a recent, novel Hamiltonian formulation of the gravitational interaction of spinning binaries, we extend the Effective One Body (EOB) description of the dynamics of two spinning black holes to next-to-leading order (NLO) in the spin-orbit interaction. The spin-dependent EOB Hamiltonian is constructed from four main ingredients: (i) a transformation between the ‘effective’ Hamiltonian and the ‘real’ one, (ii) a generalized effective Hamilton-Jacobi equation involving higher powers of the momenta, (iii) a Kerr-type effective metric (with Padé-resummed coefficients) which depends on the choice of some basic ‘effective spin vector’ $\bf{S}_{\rm eff}$, and which is deformed by comparable-mass effects, and (iv) an additional effective spin-orbit interaction term involving another spin vector $\bsigma$. As a first application of the new, NLO spin-dependent EOB Hamiltonian, we compute the binding energy of circular orbits (for parallel spins) as a function of the orbital frequency, and of the spin parameters. We also study the characteristics of the last stable circular orbit: binding energy, orbital frequency, and the corresponding dimensionless spin parameter $\hat{a}_{\rm LSO}\equiv c J_{\rm LSO}/\boldsymbol(G(H_{\rm LSO}/cˆ2)ˆ2\boldsymbol)$. We find that the inclusion of NLO spin-orbit terms has a significant ‘moderating’ effect on the dynamical characteristics of the circular orbits for large and parallel spins.

0803.0915
(/preprints)

2008-03-06, 22:15
**[edit]**

© M. Vallisneri 2012 — last modified on 2010/01/29

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