The SAGA Survey: I. Satellite Galaxy Populations Around Eight Milky Way
  Analogs
  We present the survey strategy and early results of the "Satellites Around
Galactic Analogs" (SAGA) Survey. The SAGA Survey's goal is to measure the
distribution of satellite galaxies around 100 systems analogous to the Milky
Way down to the luminosity of the Leo I dwarf galaxy ($ M_r < -12.3 $). We
define a Milky Way analog based on $K$-band luminosity and local environment.
Here, we present satellite luminosity functions for 8 Milky Way analog galaxies
between 20 to 40 Mpc. These systems have nearly complete spectroscopic coverage
of candidate satellites within the projected host virial radius down to $ r_o <
20.75 $ using low redshift $gri$ color criteria. We have discovered a total of
25 new satellite galaxies: 14 new satellite galaxies meet our formal criteria
around our complete host systems, plus 11 additional satellites in either
incompletely surveyed hosts or below our formal magnitude limit. Combined with
13 previously known satellites, there are a total of 27 satellites around 8
complete Milky Way analog hosts. We find a wide distribution in the number of
satellites per host, from 1 to 9, in the luminosity range for which there are
five Milky Way satellites. Standard abundance matching extrapolated from higher
luminosities predicts less scatter between hosts and a steeper luminosity
function slope than observed. We find that the majority of satellites (26 of
27) are star-forming. These early results indicate that the Milky Way has a
different satellite population than typical in our sample, potentially changing
the physical interpretation of measurements based only on the Milky Way's
satellite galaxies.
