We present an updated and improved M _ { bh } - \sigma diagram containing 64 galaxies for which M _ { bh } measurements ( not just upper limits ) are available .
Due to new and increased black hole masses at the high-mass end , and a better representation of barred galaxies at the low-mass end , the “ classical ” ( all morphological type ) M _ { bh } - \sigma relation for predicting black hole masses is \log ( M _ { bh } / M _ { \odot } ) = ( 8.13 \pm 0.05 ) + ( 5.13 \pm 0.34 ) \log [ \sigma / 200 { km% s } ^ { -1 } ] , with an r.m.s .
scatter of 0.43 dex .
Modifying the regression analysis to correct for a hitherto over-looked sample bias in which black holes with masses < 10 ^ { 6 } M _ { \odot } are not ( yet ) detectable , the relation steepens further to give \log ( M _ { bh } / M _ { \odot } ) = ( 8.15 \pm 0.06 ) + ( 5.95 \pm 0.44 ) \log [ \sigma / 200 { km% s } ^ { -1 } ] .
We have also updated the “ barless ” and “ elliptical-only ” M _ { bh } - \sigma relations introduced by Graham and Hu in 2008 due to the offset nature of barred galaxies .
These relations have a total scatter as low as 0.34 dex and currently define the upper envelope of points in the M _ { bh } - \sigma diagram .
They also have a slope consistent with a value 5 , in agreement with the prediction by Silk & Rees based on feedback from massive black holes in bulges built by monolithic-collapse .

Using updated virial products and velocity dispersions from 28 active galactic nuclei , we determine that the optimal scaling factor f — which brings their virial products in line with the 64 directly measured black hole masses — is 2.8 ^ { +0.7 } _ { -0.5 } .
This is roughly half the value reported by Onken et al .
and Woo et al. , and consequently halves the mass estimates of most high-redshift quasars .
Given that barred galaxies are , on average , located \sim 0.5 dex below the “ barless ” and “ elliptical-only ” M _ { bh } - \sigma relations , we have explored the results after separating the samples into barred and non-barred galaxies , and we have also developed a preliminary corrective term to the velocity dispersion based on bar dynamics .
In addition , given the recently recognised coexistence of massive black holes and nuclear star clusters , we present the first ever ( M _ { bh } + M _ { nc } ) - \sigma diagram and begin to explore how galaxies shift from their former location in the M _ { bh } - \sigma diagram .