Absorption effects due to spin in the worldline approach to black hole dynamics

We generalize the effective point particle approach to black hole dynamics to include spin. In this approach, dissipative effects are captured by degrees of freedom localized on the worldline. The absorptive properties of the black hole are determined by correlation functions which can be matched with the graviton absorption cross section in the long wavelength approximation. For rotating black holes, superradiance is responsible for the leading contribution. The effective theory is then used to predict the power loss due to spin in the dynamics of nonrelativistic binary systems. An enhancement of three powers of the relative velocity is found with respect to the nonrotating case. Then we generalize the results to other types of constituents in the binary system, such as rotating neutron stars. Finally, we compute the power loss absorbed by a test spinning black hole in a given spacetime background.

Figure 1

Feynman diagram whose imaginary part gives the leading order contribution to the absorptive cross section. The dots correspond to insertions of leading multipole worldline operators.

Figure 2

Leading order contribution to the absorptive potential. The dots correspond to insertions of the leading worldline multipole operators.