1999A&A...346..713K

We study the formation of the spectra in Advection Dominated Accretion Flows (ADAFs) around Kerr black holes. We use a Monte Carlo approach and fully general relativistic treatment to follow the paths of individual photons and model their scattering with mildly relativistic, thermal electrons of the two temperature plasma present in the flow. We are mostly interested in the dependence of the spectra on the black hole angular momentum, and we find that the influence of the black hole rotation rate on the flow structure has an impact on the resulting spectra. The flows around the fast rotating holes produce relatively harder spectra. This property of the models should be taken into account when modeling the individual sources and the population of inefficiently accreting black holes in the Universe.