Abstract
We report the discovery of 23 globular cluster (GC) candidates around the
relatively isolated dwarf galaxy IC 2574 within the Messier 81 (M81) group, at
a distance of 3.86 Mpc. We use observations from the HST Advanced Camera for
Surveys (ACS) to analyse the imaging in the F814W and F555W broadband filters.
Our GC candidates have luminosities ranging from $-5.9 \geq M_V \geq -10.4$ and
half-light radii of $1.4 \leq r_h \leq 11.5$ pc. We find the total number of
GCs ($N_{\mathrm{GC}})=27\pm5$ after applying completeness corrections, which
implies a specific frequency of $S_N = 4.0\pm0.8$, consistent with expectations
based on its luminosity. The GC system appears to have a bimodal colour
distribution, with 30% of the GC candidates having redder colours. We also find
5 objects with extremely blue colours that could be young star clusters linked
to an intense star formation episode that occurred in IC 2574 $\sim$1 Gyr ago.
We make an independent measurement of the halo mass of IC 2574 from its
kinematic data, which is rare for low mass galaxies, and find log $M_{200} =
10.93 \pm 0.08$. We place the galaxy on the well-known GC system mass-halo mass
relation and find that it agrees well with the observed near-linear relation.
IC 2574 has a rich GC population for a dwarf galaxy, which includes an
unusually bright $\omega$ Cen-like GC, making it an exciting nearby laboratory
for probing the peculiar efficiency of forming massive GCs in dwarf galaxies.