Supersymmetry of the 2+1 black holes
O. Coussaert, M. Henneaux
TL;DR
It is argued that the zero-mass hole is the ground state of (1,1) adS supergravity with periodic (``Ramond'') boundary conditions on the spinor fields.
Abstract
The supersymmetry properties of the asymptotically anti-de Sitter black holes of Einstein theory in 2+1 dimensions are investigated. It is shown that (i) the zero mass black hole has two exact super- symmetries; (ii) extreme $lM=|J|$ black holes with $M \not= 0$ have only one; and (iii) generic black holes do not have any. It is also argued that the zero mass hole is the ground state of (1,1)-adS supergravity with periodic (``Ramond") boundary conditions on the spinor fields.