2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/72681Using ideas from an article of P. Bieliavsky, M. Rooman and Ph. Spindel on BTZ black holes, I construct a family of interesting examples of quasi-Poisson actions as defined by A. Alekseev and Y. Kosmann-Schwarzbach. As an application, I obtain a genuine Poisson structure on $SL(2,R)$ which induces a Poisson structure on a BTZ black hole.8 pages. Comments welcomedDifferential GeometryMathematical Physics53D17; 53Z05text