Determination of the Magnitude of the Spins of Supermassive Black Holes and the Magnetic Fields in Active Galactic Nuclei

Abstract

Limits on the value of the spins of supermassive black holes (SMBH) in Seyfert-type active galactic nuclei (AGN) are calculated using two hybrid models for the generation of relativistic jets: the Meier model and a model of tandem Blandford-Znajek and Blandford-Payne processes. A comparison of our calculations with limits on the spin obtained by x-ray reflection spectroscopy shows that they are in good agreement for the tandem model. This shows that the magnetic field pressure is roughly equal to the radiation ressure in the accretion disk in the region of the last stable orbit. The magnitudes of the magnetic fields at the radii of the last stable orbit in the accretion disk and the event horizon of a supermassive black hole are also determined for objects in a list of 28 radio quasars. The important result is that the magnetic energy density near the radius of the event horizon turns out to be significantly higher than the energy density of the accretion gas. This may indicate the existence of a mechanism for amplification of the magnetic field near the event horizon of black holes located in the center of powerful radio quasars.