Cooling a hot disk around a supermassive black hole by a star

If a supermassive black hole resides in the centers of galaxies, several effects are expected to be observed. It is likely that accretion disks are around the supermassive black hole. Stellar interactions with the accretion flows around the supermassive black hole play a role in that a flying-by star may cool a hot accretion disk as a result of Comptonization. It is shown that the Comptonization of the stellar emission will take place in a hot accretion disk such as the advection-dominated accretion flows (ADAFs) around the supermassive black hole and become a relatively important source of the accretion disk cooling when the mass accretion rate is low. We suggest that such a stellar cooling can be observed in the radio frequency regime since the synchrotron luminosity of the ADAFs depends strongly on the electron temperature and occurs much more frequently than a tidal disruption event.