2381/11284448.v1 Kastytis Zubovas Kastytis Zubovas Andrew King Andrew King Slow and massive: low-spin SMBHs can grow more University of Leicester 2019 accretion accretion discs galaxies: active quasars: general 2019-11-27 16:50:39 Journal contribution https://figshare.le.ac.uk/articles/journal_contribution/Slow_and_massive_low-spin_SMBHs_can_grow_more/11284448 Active galactic nuclei (AGNs) probably control the growth of their host galaxies via feedback in the form of wide-angle wind-driven outflows. These establish the observed correlations between supermassive black hole (SMBH) masses and host galaxy properties, e.g. the spheroid velocity dispersion σ. In this paper we consider the growth of the SMBH once it starts driving a large-scale outflow through the galaxy. To clear the gas and ultimately terminate further growth of both the SMBH and the host galaxy, the black hole must continue to grow its mass significantly, by up to a factor of a few, after reaching this point. The mass increment Δ<em>M</em><sub>BH</sub> depends sensitively on both galaxy size and SMBH spin. The galaxy size dependence leads to Δ<em>M</em><sub>BH</sub> ∝ σ5 and a steepening of the <em>M</em>–σ relation beyond the analytically calculated <em>M</em> ∝ σ4, in agreement with observation. Slowly spinning black holes are much less efficient in producing feedback, so at any given σ the slowest spinning black holes should be the most massive. Current observational constraints are consistent with this picture, but insufficient to test it properly; however, this should change with upcoming surveys.