Black hole mass and quasar radio emission

• Relationship between $M_\mathrm{BH}$ and quasar radio emission:
  • No correlation between $M_\mathrm{BH}$ and SF at all masses.
  • No correlation between $M_\mathrm{BH}$ and AGN at most masses.
  • Quasars hosting the $20\%$ most massive SMBHs are 2 to 3 times more likely to host powerful radio jets than quasars hostinglower mass SMBHs.
  • Radio enhancement in massive quasars only accounts for the $\sim5\%$ most radio bright quasars.

Whether supermassive black hole (SMBH) mass ($M_\mathrm{BH}$) affects the radio luminosity of quasars remains a long-debated issue, and understanding the role of $M_\mathrm{BH}$ in the evolution of quasars can be pivotal in unveiling the mechanism of AGN feedback.

In this work, based on the fully Bayesian two-component model presented in Yue et al. (2024), we study the impact of $M_\mathrm{BH}$ on the radio emission from quasars, separating the contibutions from host galaxy SF and AGN activity.

By modelling the radio flux density distribution of Sloan Digital Sky Survey (SDSS) quasars from LOFAR Two-metre Sky Survey Data Release 2, we find no correlation between $M_\mathrm{BH}$ and SF at all masses, for quasars at a given redshift and bolometric luminosity. The same is true for AGN activity across the majority of $M_\mathrm{BH}$ values; however, quasars hosting the $20\%$ most massive SMBHs are 2 to 3 times more likely to host powerful radio jets than lower mass SMBHs in otherwise similar quasars. We propose a new physically motivated definition of quasar radio loudness that unifies previously divergent observational results, and demonstrates that such radio enhancement only affects the $\sim5\%$ most radio bright quasars given a certain redshift and bolometric luminosity.

The possible physical origins of this radio excess in the most massive and radio-bright quasar population remains an interest for future study, with potential links to accretion mode shifts, large/small scale environment, black hole spin, and observational bias.