Transition of BH feeding from the quiescent regime into star-forming cold disk regime

We study the properties of rotating accretion flows on to supermassive black holes (SMBIls) using, axisymmetric two-dimensional hydrodynamical simulations with radiative cooling, and B11 feedback. The simulations resolve the accretion dynamics of gas outside from the B11 influence radius through an inner accretion disc. For lower Bondi accretion rates in units of the Eddington rate ((111/B << 10 3 Ar./Edd). the BH feeding is suppressed due to turbulent motion by several orders of magnitude frotn the Bondi rate with outflows to the Bondi radius nearly balancing inflows. Thus, the radiative luminosity results in as low as 10 1u 107 LEdd, where LFdd is the Eddington luminosity. For higher rates of /111j >, 10 3 /1./Rid, the optically thin accreting gas cools via free free emission and forms a geometrically thin disc, which feeds the RH efficiently and increases the radiative luminosity to >JO 3 Lud. The transitional behaviour of accreting IiHs in galactic nuclei from radiatively inefficient phases to cold disc accretion naturally explains (1) the reason for the offset between the observed luminosities and theoretical predictions for nearby quiescent SMBHs, and (2) the conditions to fuel gas into the nuclear SWIM In addition, the cold disc formed in galactic nuclei tends to be gravitationally unstable and leads to star formation when the Bondi rate is as high as /114B > 10-2 M,-,-, yr-1. This is a plausible explanation of the correlation observed between star formation rates and BH feeding rates in Seyfert galaxies.