  Massive black holes (BHs) inhabit local galaxies, including the Milky Way and
some dwarf galaxies. BH formation, occurring at early cosmic times, must
account for the properties of BHs in today's galaxies, notably why some
galaxies host a BH, and others do not. We investigate the formation,
distribution and growth of BH `seeds' by using the adaptive mesh refinement
code Ramses. We develop an implementation of BH formation in dense,
low-metallicity environments, as advocated by models invoking the collapse of
the first generation of stars, or of dense nuclear star clusters. The seed
masses are computed one-by-one on-the-fly, based on the star formation rate and
the stellar initial mass function. This self-consistent method to seed BHs
allows us to study the distribution of BHs in a cosmological context and their
evolution over cosmic time. We find that all high-mass galaxies tend to a host
a BH, whereas low-mass counterparts have a lower probability of hosting a BH.
After the end of the epoch of BH formation, this probability is modulated by
the growth of the galaxy. The simulated BHs connect to low-redshift
observational samples, and span a similar range in accretion properties as
Lyman-Break Analogs. The growth of BHs in low-mass galaxies is stunted by
strong supernova feedback. The properties of BHs in dwarf galaxies thus remain
a testbed for BH formation. Simulations with strong supernova feedback, which
is able to quench BH accretion in shallow potential wells, produce galaxies and
BHs in better agreement with observational constraints.
