Why the astrophysical Black Hole Candidates may not be black holes at   all
  In a recent paper[1], it has been shown that, there cannot be any rotating (Kerr) Black Hole (BH) with finite mass in order that the generic properties associated with the symmetries of stationary axisymmetric Einstein equations are obeyed, i.e, in order to have m\ge 0, we must have $a=0$. In other words, all observed chargeless BHs with finite masses must be non-rotating Schwarzschild BHs. Here, by comparing the invariant 4 volume associated with original Kerr metric [2] with the Boyer-Lindquist version of the same [3], we further find that, stationary axisymmetric {\em vacuum} Einstein solutions actually correspond to m=0 in addition to a=0! This means that if the Kerr solution is a unique one, the Schwarzschild BHs too correspond to only m=0 and therefore the observed BH candidates (BHs) with m >0 are not BHs at all. This is in agreement some detailed analysis of recent observations[4-7] which suggest the the BHCs have strong intrinsic magnetic moment rather than any Event Horizon. If one would derive the Boyer-Lindquist metric in a straightforward manner by using the Backlund transformation, it would follow that a= m sin phi, where phi is the azimuth angle. This relationship directly confirms the result that for a supposed rotating BH, actually, both a=m=0. 
Abhas Mitra