Person:

Song, Wei

The superradiant scattering of a scalar field with frequency and angular momentum (w,m) by a near-extreme Kerr black hole with mass and spin (M, J) was derived in the seventies by Starobinsky, Churilov, Press and Teukolsky. In this paper we show that for frequencies scaled to the superradiant bound the full functional dependence on (w,m,M, J) of the scattering amplitudes is precisely reproduced by a dual twodimensional conformal field theory in which the black hole corresponds to a specific thermal state and the scalar field to a specific operator. This striking agreement corroborates a conjectured Kerr/CFT correspondence.

Three dimensional Einstein gravity with negative cosmological constant (-1/\ell^2) deformed by a gravitational Chern-Simons action with coefficient (1/\mu) is studied in an asymptotically (AdS_3) spacetime. It is argued to violate unitary or positivity for generic (\mu) due to negative-energy massive gravitons. However at the critical value (\mu\ell=1), the massive gravitons disappear and BTZ black holes all have mass and angular momentum related by (\ell M=J). The corresponding chiral quantum theory of gravity is conjectured to exist and be dual to a purely right-moving boundary CFT with central charges ((c_L,c_R)=(0,3\ell /G)).

Near-superradiant scattering of charged scalars and fermions by a near-extreme Kerr-Newman black hole and photons and gravitons by a near-extreme Kerr black hole are computed as certain Fourier transforms of correlators in a two-dimensional conformal field theory. The results agree with the classic spacetime calculations from the 1970s, thereby providing good evidence for a conjectured Kerr-Newman/CFT correspondence.