Curvature singularity of the distributional BTZ black hole geometry
  For the non-rotating BTZ black hole, the distributional curvature tensor field is found. It is shown to have singular parts proportional to a $\delta$-distribution with support at the origin. This singularity is related, through Einstein field equations, to a point source. Coordinate invariance and independence on the choice of differentiable structure of the results are addressed. 
N. R. Pantoja, H. Rago and R. O. Rodriguez