Department of Astronomy
Center for Radiophysics & Space Research

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"Hamiltonian" Dynamics of Self-Forced Motion in Kerr Spacetime

6Wednesday, May. 6

Soichiro Isoyama

12:15 PM

622 Space Sciences

### Gravitational waves observations from compact objects inspiralling into massive black holes are promising targets to test GR in strong field regime. When the mass ratio is small, the problem admits a perturbative description, where the corrections to the geodesic motion of the smaller object are best handled by the notion of a gravitational self-force. In this talk, we propose a "Hamiltonian" formulation of the self-force dynamics in Kerr spacetime, which describes the binary dynamics linear order in mass ratio in terms of a geodesic motion in a certain locally defined effective smooth spacetime. Our formulation uses action-angle variables to respect the integrability of the Kerr geodesics motion, and gives a significantly simplified method to compute the post-geodesic motion in Kerr spacetime. For the conservative dynamics, we show that our Hamiltonian is effectively "integrable", and present the recent calculation of a the frequency shift of the inner most stable circular orbit in Kerr spacetime due to the conservative self-force. We also sketch how we practically formulate the long-term inspiral dynamics, using the special choice of gauge.