Attempt to find a correlation between the spin of stellar-mass black   hole candidates and the power of steady jets: relaxing the Kerr black hole   hypothesis
  The rotational energy of a black hole can be extracted via the Blandford-Znajek mechanism and numerical simulations suggest a strong dependence of the power of the produced jet on the black hole spin. A recent study has found no evidence for a correlation between the spin and the power of steady jets. If the measurements of the spin and of the jet power are correct, it leads one to conclude that steady jets are not powered by the black hole spin. In this paper, I explore another possibility: I assume that steady jets are powered by the spin and I check if current observations can be explained if astrophysical black hole candidates are not the Kerr black hole predicted by General Relativity. It turns out that this scenario might indeed be possible. While such a possibility is surely quite speculative, it is definitively intriguing and can be seriously tested when future more accurate measurements will be available. 
Cosimo Bambi
gr-qc astro-ph.HE