SPACE, TIME AND FUNDAMENTAL INTERACTIONS

SPINS OF SUPERMASSIVE BLACK HOLES

Dokuchaev V.I.

Shapes of black hole images, viewed by a distant observer, depend on the distribution of emitting matter around black holes. There are two distinctive astrophysical cases: (1) Luminous stationary background behind the black hole (emission of photons outside the photon spheres). In this case the dark classical black hole shadow is viewed, which is a capture photon cross-section in the black hole gravitational field. (2) Luminous accretion inflow near the black hole event horizon (emission of photons inside the photon spheres). In this case the dark event horizon shadow is viewed, which is a lensed image of the event horizon globe. The existence of hot accreting matter in the vicinity of black hole event horizons is predicted by the Blandford-Znajek mechanism. The basic feature of this mechanism is the existing of electric current embracing the black hole and heating the accretion disk very near the black hole event horizon providing the main contribution to the black hole luminosity. We used the numerically calculated sizes of dark spots in the EHT images of supermassive black holes SgrA* and M87* for inferring their spins, 0.65 < a < 0.9 and a > 0.75, respectively