Magellanic-Cloud Like Satellites are Rare

To investigate hierarchical models of galaxy formation and evolution it is important to have large samples of true satellites, extending to the faintest possible luminosities. We have used Hα narrow-band imaging to search for star-forming satellite galaxies around 143 field spiral galaxies comparable to the Milky Way and found 63 candidate satellites associated with 47 host galaxies. A subset of 12 candidate satellites and their 11 host galaxies were spectroscopically observed to test if the candidates were true satellites and bound to their host. This confirmed that Hα imaging is a reliable method for searching for faint satellites. Within the overall sample of 63 satellites only ~6 could be considered analogous with the LMC and ~14 with the SMC