  Nuclear star clusters (NCs) are found to exist in the centres of many
galaxies and appear to follow scaling relations similar to those of
super-massive black holes. Previous analytical work has suggested that such
relations are a consequence of feedback regulated growth. We explore this idea
using high resolution hydrodynamical simulations, focusing on the validity of
the simplifying assumptions made in analytical models. In particular, we
investigate feedback emanating from multiple stellar sources rather than from a
single source, as is usually assumed, and show that collisions betweens shells
of gas swept up by feedback leads to momentum cancellation and the formation of
high density clumps and filaments. This high density material is resistant both
to expulsion from the galaxy potential and to disruption by feedback; if it
falls back onto the NC, we expect the gas to be available for further star
formation or for feeding a central black hole. We also note our results may
have implications for the evolution of globular clusters and stellar clusters
in high redshift dark matter halos.
