Black holes of intermediate masses in globular clusters: constraints on   a spin of a black hole
  In this paper we determined values of a spin of central black holes of the intermediate masses in globular clusters. For determination of value of a spin we used the known relation between the kinetic power of the relativistic jet and observable radio-luminosity of the region near to a central black hole, and our estimates have based on the known Blandford-Znajek mechanism. The value of a magnetic field strength near the event horizon of a black hole was derived via magnetic coupling mechanism. Accretion rate was derived using Bondi-Hoyle mechanism. 
S.D. Buliga, V.I. Globina, Yu.N. Gnedin, T.M. Natsvlishvili, M.Yu.   Piotrovich, N.A. Shaht
astro-ph.CO