On neutral scalar radiation by a massive orbiting star in extremal   Kerr-Newman black hole
  In this short note we extend the work of 1401.3746 about gravity waves by a massive orbiting star in an extremal Kerr black hole to an extremal Kerr- Newman black hole for scalar radiation, and still find that it has a CFT interpretation from Kerr-Newman/CFT. In addition, we investigate on electromagnetic radiation with Kerr/CFT, which a detailed analysis isn't given by 1401.3746. 
Nan Bai, Yi-Hong Gao, Xiao-bao Xu
hep-th