Talk detail

Participant	Wang, Mengjie
Institution	Aveiro University - Campus Universitario de Santiago - Aveiro - - Portugal

Session	BH4	Accepted	Yes	Order	17	Time	17:40	10'
Talk	Oral abstract	Title	Boundary conditions for Maxwell perturbations in Kerr-AdS black holes and their applications
Coauthors	Herdeiro, Carlos; Sampaio, Marco
Abstract	Perturbations of asymptotically Anti-de-Sitter (AdS) spacetimes are often considered by imposing field vanishing boundary conditions (BCs) at the AdS boundary. Such BCs, of Dirichlet-type, imply a vanishing energy flux at the boundary, but the converse is, generically, not true. Regarding AdS as a gravitational box, we consider vanishing energy flux (VEF) BCs as a more fundamental physical requirement and we show that these BCs can lead to a new branch of modes. As a concrete example, we consider Maxwell perturbations on Kerr-AdS black holes in the Teukolsky formalism. After imposing VEF BCs, we get a set of two Robin BCs, even for Schwarzschild-AdS black holes. We find that one of the Robin BCs yields the quasinormal spectrum reported in the literature, while the other one unveils a new branch for the quasinormal spectrum. We will also report some results on superradiant instabilities and vector clouds in Kerr-AdS background.
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