Confirmation of Faint Dwarf Galaxies in the M81 Group
  We have followed up on the results of a 65 square degree CFHT/MegaCam imaging
survey of the nearby M81 Group searching for faint and ultra-faint dwarf
galaxies. The original survey turned up 22 faint candidate dwarf members. Based
on two-color HST ACS/WFC and WFPC2 photometry, we now confirm 14 of these as
dwarf galaxy members of the group. Distances and stellar population
characteristics are discussed for each. To a completeness limit of M_r' = -10,
we find a galaxy luminosity function slope of -1.27+-0.04 for the M81 group. In
this region, there are now 36 M81 group members known, including 4 blue compact
dwarfs, 8 other late types including the interacting giants M81, NGC 3077, and
M82, 19 early type dwarfs, and at least 5 potential tidal dwarf galaxies. We
find that the dSph galaxies in M81 appear to lie in a flattened distribution,
similar to that found for the Milky Way and M31. One of the newly discovered
dSph galaxies has properties similar to the ultra-faint dwarfs being found in
the Local Group with a size R_e ~ 100 pc and total magnitude estimates M_r' =
-6.8 and M_I ~ -9.1.
