Conformal entropy as a consequence of the properties of stationary Killing horizons

We show that the microscopic black hole entropy formula based on Virasoro algebra can be derived from the usual properties of stationary Killing horizons alone and the absence of singularities of curvature invariants on them. In such a way some usual additional assumptions are shown to be fulfilled. In addition, for all quantities power expansion near the horizon and thus explicit insight of the limiting procedure is given. More important the near horizon conformal symmetry proposed by Carlip together with its consequences on microscopic entropy is given a clear geometric origin.