Black holes in truncated higher spin AdS3 gravity

We study the higher spin black holes in a truncated version of higher spin gravity in AdS(3). This theory contains only finite number of even spins s = 2, 4, ... , 2N. We mainly focus on the simplest case, so-called (Type I and II) spin (4) over tilde gravity, which contains only spin 2 and spin 4 fields. This spin (4) over tilde gravity is as simple as spin 3 gravity, thus provides another example to test various ideas on higher spin gravity. We find that the asymptotical symmetry of this spin (4) over tilde gravity is a classical W (2, 4)-symmetry. Moreover, we study the black hole solution with pure spin 4 hair and discuss its thermodynamics. One important feature of this black hole is that its entropy could be written in compact forms. Furthermore, we investigate a G(2) generated higher spin gravity. This higher spin gravity only contains spin 2 and spin 6 fields which makes it different from other kinds of higher spin gravity. We find the corresponding black hole with spin 6 hair, and discuss its thermodynamics analytically.