  The relation between the mass of supermassive black holes located in the
center of the host galaxies and the kinetic energy of random motions of the
corresponding bulges can be reinterpreted as an age-temperature diagram for
galaxies. This relation fits the experimental data better than the M_bh-M_G,
M_bh-L_G, and M_bh-sigma laws. The validity of this statement has been
confirmed by using three samples extracted from different catalogues of
galaxies. In the framework of the LambdaCDM cosmology our relation has been
compared with the predictions of two galaxy formation models based on the
Millennium Simulation.
