Globular cluster systems in nearby dwarf galaxies - II. Nuclear star
  clusters and their relation to massive Galactic globular clusters
  (Abridged) Using luminosities and structural parameters of globular clusters
(GCs) in the nuclear regions (nGCs) of low-mass dwarf galaxies from HST/ACS
imaging we derive the present-day escape velocities (v_esc) of stellar ejecta
to reach the cluster tidal radius and compare them with those of Galactic GCs
with extended (hot) horizontal branches (EHBs-GCs). For EHB-GCs, we find a
correlation between the present-day v_esc and their metallicity as well as
(V-I)_0 colour. The similar v_esc, (V-I)_0 distribution of nGCs and EHB-GCs
implies that nGCs could also have complex stellar populations. The v_esc-[Fe/H]
relation could reflect the known relation of increasing stellar wind velocity
with metallicity, which in turn could explain why more metal-poor clusters
typically show more peculiarities in their stellar population than more
metal-rich clusters of the same mass do. Thus the cluster v_esc can be used as
parameter to describe the degree of self-enrichment. The nGCs populate the same
Mv vs. rh region as EHB-GCs, although they do not reach the sizes of the
largest EHB-GCs like wCen and NGC 2419. We argue that during accretion the rh
of an nGC could increase due to significant mass loss in the cluster vicinity
and the resulting drop in the external potential in the core once the dwarf
galaxy dissolves. Our results support the scenario in which Galactic EHB-GCs
have originated in the centres of pre-Galactic building blocks or dwarf
galaxies that were later accreted by the Milky Way.
