  We study the relation between nuclear massive black holes and their host
spheroid gravitational potential. Using AMR numerical simulations, we analyze
how gas is transported in the nuclear (central kpc) regions of galaxies. We
study the gas fueling onto the inner accretion disk (sub-pc scale) and the star
formation in a massive nuclear disk like those generally found in
proto-spheroids (ULIRGs, SCUBA Galaxies). These sub-pc resolution simulation of
gas fueling that is mainly depleted by star formation naturally satisfy the
`M_BH - $M_virial' relation, with a scatter considerably less than the observed
one. We found a generalized version of Kennicutt-Schmidt Law for starbursts is
satisfied, in which the total gas depletion rate (dot{M}_gas = dot{M}_BH +
dot{M}_SF) is the one that scales as M_gas/t_orbital. We also found that the
`M_BH - sigma' relation is a byproduct of the `M_BH - M_virial' relation in the
fueling controlled scenario.
