Intermediate-mass black holes in globular clusters: constraints on the spin of a black hole

Abstract

The spin of central black holes with intermediate masses in globular clusters is determined using the well known relationship between the kinetic power of a relativistic jet and the observed radio luminosity of the region closest to a central black hole. The estimate of the magnitude of the spin is based on the known Blandford-Znajek mechanism. The magnetic field near the event horizon of a black hole is determined using a magnetic coupling mechanism that assumes equality between the densities of the magnetic and kinetic energies of the accreting gas (the Magnetic Coupling Model). The rate of accretion $$ \dot{M} $$ is derived on the basis of the Bondi-Hoyle mechanism.