Formation of globular clusters in dwarf galaxies of the Local Group
First author: Yingtian Chen
The existence of globular clusters (GCs) in a few satellite galaxies, and
their absence in majority of dwarf galaxies, present a challenge for models
attempting to understand the origins of GCs. In addition to GC presence
appearing stochastic and difficult to describe with average trends, in the
smallest satellite galaxies GCs contribute a substantial fraction of total
stellar mass. We investigate the stochasticity and number of GCs in dwarf
galaxies using an updated version of our model that links the formation of GCs
to the growth of the host galaxy mass. We find that more than 50% of dwarf
galaxies with stellar mass $M_\star\lesssim 2\times10^7\ M_\odot$ do not host
GCs. However, dwarfs with $M_\star\simeq10^8\ M_\odot$ almost always contain
some GCs, with a median number $\sim 10$. These predictions are in agreement
with the observations of the Local Volume dwarfs. We also confirm the
near-linear GC system mass–halo mass relation down to $M_{\rm h}\simeq10^8
M_\odot$ under the assumption that GC formation and evolution in galaxies of
all mass can be described by the same physical model. A detailed case study of
two model dwarfs that resemble the Fornax dwarf spheroidal galaxy shows that
observational samples can be notably biased by incompleteness below detection
limit and at large radii.