Alister W. Graham, Nicholas Scott
From a sample of 72 galaxies with reliable supermassive black hole masses M_(bh), we derive the M_(bh)-(host spheroid luminosity, L) relation for (i) the subsample of 24 core-Sersic galaxies with partially depleted cores, and (ii) the remaining subsample of 48 Sersic galaxies. Using (K_s)-band Two Micron All Sky Survey data, we find the near-linear relation M_(bh) ~ L_(K_s)^(1.10+/-0.20) for the core-Sersic spheroids thought to be built in additive dry merger events, while M_(bh) ~ L_(K_s)^(2.73+/-0.55) for the Sersic spheroids built from gas-rich processes. After converting literature B-band disk galaxy magnitudes into inclination- and dust-corrected bulge magnitudes, via a useful new equation presented herein, we obtain a similar result. Unlike with the M_(bh)-sigma diagram, which is also updated here using the same galaxy sample, it remains unknown whether barred and non-barred Sersic galaxies are offset from each other in the M_(bh)-L diagram. While black hole feedback has typically been invoked to explain the near-linear `Magorrian relations' and what was previously thought to be a nearly constant M_(bh)/M_(spheroid) mass ratio of ~0.2%, we advocate that the near-linear M_(bh)-L and M_(bh)-M_(spheroid) relations at high masses may have instead largely arisen from the simple, additive dry merging of galaxies, and that feedback results in a dramatically different scaling relation. We therefore introduce a new, quadratic cold-gas 'quasar' mode feeding equation for semi-analytical models to reflect the quadratic mass growth of black holes in Sersic galaxies built amidst gas-rich processes. Finally, we use our new Sersic M_(bh)-L equations to predict the masses of candidate intermediate mass black holes in almost 50 low luminosity spheroids containing active galactic nuclei, possibly having discovered the missing population between stellar mass and supermassive black holes.
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http://arxiv.org/abs/1211.3199
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