Chennai Mathematical Institute


3.30 pm, Seminar Hall
Hairy Black Holes in global-AdS and a Box

P N Bala Subramanian
Institute of Mathematical Sciences, Chennai.


We investigate the phase structure of Einstein-Maxwell-Scalar system with a negative cosmological constant. For the conformally coupled scalar, an intricate phase diagram is charted out between the four relevant solutions: global AdS, boson star, Reissner-Nordstrom black hole and the hairy black hole. We also do a systematic study of the phases of gravity coupled to an electromagnetic field and charged scalar in flat space, with box boundary conditions. The phase diagram of the system is analogous to that of AdS black holes, but we emphasize the differences and explain their origin. Once the scalar is added, we show that the system admits both boson stars as well as hairy black holes as solutions, providing yet another way to evade flat space no-hair theorems. Furthermore both these solutions can exist as stable phases in regions of the phase diagram. We also point out previously unnoticed subtleties associated to the definition quasi-local charges for gravitating scalar fields in finite regions.