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We present Hubble Space Telescope imaging of two ultra diffuse galaxies (UDGs) with measured stellar velocity dispersions in the Coma cluster. The galaxies, Dragonfly 44 and DFX1, have effective radii of 4.7 kpc and 3.5 kpc and velocity dispersions of $47^{+8}_{-6}$ km/s and $30^{+7}_{-7}$ km/s, respectively. Both galaxies are associated with a striking number of compact objects, tentatively identified as globular clusters: $N_{rm gc}=74pm 18$ for Dragonfly 44 and $N_{rm gc}=62pm 17$ for DFX1. The number of globular clusters is far higher than expected from the luminosities of the galaxies but is consistent with expectations from the empirical relation between dynamical mass and globular cluster count defined by other galaxies. Combining our data for these two objects with previous HST observations of Coma UDGs we find that UDGs have a factor of $6.9^{+1.0}_{-2.4}$ more globular clusters than other galaxies of the same luminosity, in contrast to a recent study of a similar sample by Amorisco et al. (2017), but consistent with earlier results for individual galaxies. The Harris et al. (2017) relation between globular cluster count and dark matter halo mass implies a median halo mass of $M_{rm halo}sim 1.5times 10^{11},{rm M}_{odot}$ for the sixteen Coma UDGs that have been observed with HST so far, with the largest and brightest having $M_{rm halo}sim 5times 10^{11},{rm M}_{odot}$.
Ultra-diffuse galaxies (UDGs) are unusual galaxies with low luminosities, similar to classical dwarf galaxies, but sizes up to $sim!5$ larger than expected for their mass. Some UDGs have large populations of globular clusters (GCs), something unexpec
We report the discovery of 854 ultra diffuse galaxies (UDGs) in the Coma cluster using deep R band images, with partial B, i, and Halpha band coverage, obtained with the Subaru telescope. Many of them (332) are Milky Way-sized with very large effecti
Ultra diffuse galaxies (UDGs) reveal extreme properties. Here we compile the largest study to date of 85 globular cluster (GC) systems around UDGs in the Coma cluster, using new deep ground-based imaging of the known UDGs and existing imaging from th
We present a study of ultra-diffuse galaxies (UDGs) in the Virgo Cluster based on deep imaging from the Next Generation Virgo Cluster Survey (NGVS). Applying a new definition for the UDG class based on galaxy scaling relations, we define samples of 4
We present Keck/DEIMOS spectroscopy of globular clusters (GCs) around the ultra-diffuse galaxies (UDGs) VLSB-B, VLSB-D, and VCC615 located in the central regions of the Virgo cluster. We spectroscopically identify 4, 12, and 7 GC satellites of these