Authors: Alister W. Graham
The popular log-linear relation between supermassive black hole mass, Mbh, and the dynamical mass of the host spheroid, Msph, is shown to require a significant correction. Core galaxies, typically with Mbh > 2x108 MSun and thought to be formed in dry merger events, are shown to be well described by a linear relation for which the median black hole mass is 0.36% — roughly double the old value of constancy. Of greater significance is that Mbh ∝ Msph2 among the (non-pseudobulge) lower-mass systems: specifically, log[Mbh/MSun] = (1.92±0.38)log[Msph/7×1010MSun] + (8.38±0.17). `Classical' spheroids hosting a 106 MSun black hole will have Mbh/Msph ≈ 0.025%. These new relations presented herein (i) bring consistency to the relation Mbh ∝ σ5 and the fact that L ∝ σx with exponents of 5 and 2 for bright (MB < -20.5 mag) and faint spheroids, respectively, (ii) mimic the non-(log-linear) behavior known to exist in the Mbh-(Sérsic n) diagram, (iii) necessitate the existence of a previously over-looked Mbh ∝ L2.5 relation for Sérsic (i.e. not core-Sérsic) galaxies, and (iv) resolve past conflicts (in mass prediction) with the Mbh-σ relation at the low-mass end. Furthermore, the bent nature of the Mbh-Msph relation reported here for `classical' spheroids will have a host of important implications that, while not addressed in this paper, relate to (i) galaxy/black hole formation theories, (ii) searches for the fundamental, rather than secondary, black hole scaling relation, (iii) black hole mass predictions in other galaxies, (iv) alleged pseudobulge detections, (v) estimates of the black hole mass function and mass density based on luminosity functions, (vi) predictions for space-based gravitational wave detections, (vii) connections with nuclear star cluster scaling relations, (viii) evolutionary studies over different cosmic epochs, (ix) comparisons and calibrations matching inactive black hole masses with low-mass AGN data, and more.