The M101 Satellite Luminosity Function and the Halo to Halo Scatter Among Local Volume Hosts

Understand

We have obtained deep Hubble Space Telescope (HST) imaging of 19 dwarf galaxy candidates in the vicinity of M101.

• Advanced Camera for Surveys HST photometry for 2 of these objects showed resolved stellar populations and Tip of the Red Giant Branch derived distances consistent with M101 group membership.
• The other 17 were found to have no resolved stellar populations, meaning they are background low surface brightness (LSB) galaxies.
• It is notable that many LSB objects which had previously been assumed to be M101 group members based on projection have been shown to be background objects, indicating the need for future diffuse dwarf surveys to be careful in drawing conclusions about group membership without robust distance estimates.