Quenching of supermassive black hole growth around the apparent maximum mass

Understand

Recent quasar surveys have revealed that supermassive black holes (SMBHs) rarely exceed a mass of $M_{\rm BH} \sim {\rm a~few}\times10^{10}~M_{\odot}$ during the entire cosmic history.

• It has been argued that quenching of the BH growth is caused by a transition of a nuclear accretion disk into an advection dominated accretion flow, with which strong outflows and/or jets are likely to be associated.
• We investigate a relation between the maximum mass of SMBHs and the radio-loudness of quasars with a well-defined sample of $\sim 10^5$ quasars at a redshift range of $0<z<2$, obtained from the Sloan Digital Sky Surveys DR7 catalog.
• We find that the number fraction of the radio-loud (RL) quasars increases above a threshold of $M_{\rm BH} \simeq 10^{9.5}~M_{\odot}$, independent of their redshifts.