An SDSS Survey For Resolved Milky Way Satellite Galaxies. I. Detection Limits

We present the detection limits of a new survey for resolved low surface brightness satellite galaxies to the Milky Way, based on the Sloan Digital Sky Survey (SDSS). Our survey exploits SDSS's major strengths (multicolor photometry, depth, large-scale, and uniformity) by combining filter smoothing with limits in both magnitude and color space to search for low surface brightness galaxies and stellar counterparts to the compact high-velocity clouds out to the Milky Way's virial radius (∼350 kpc). Our calculated detection limits for a purely old stellar population vary with galaxy size and distance between μV,0 = 26.7 and 30.1 mag arcsec-2. These limits will allow us to detect systems whose surface brightnesses are 0.5–3.9 mag arcsec-2 fainter than Sextans, the lowest surface brightness Local Group member known. Our survey not only is sensitive to lower surface brightness stellar populations than possible with previous Local Group surveys, but will also allow us to make an unbiased and well-defined assessment of the completeness of the observed Local Group galaxy luminosity function, so that we may compare the results with the predictions of various structure formation scenarios.