The SAGA Survey. II. Building a Statistical Sample of Satellite Systems
  around Milky Way-like Galaxies
  We present the Stage II results from the ongoing Satellites Around Galactic
Analogs (SAGA) Survey. Upon completion, the SAGA Survey will spectroscopically
identify satellite galaxies brighter than $ M_{r,o} = -12.3 $ around 100 Milky
Way (MW) analogs at $ z \sim 0.01 $. In Stage II, we have more than quadrupled
the sample size of Stage I, delivering results from 127 satellites around 36 MW
analogs with an improved target selection strategy and deep photometric imaging
catalogs from the Dark Energy Survey and the Legacy Surveys. We have obtained
25,372 galaxy redshifts, peaking around $ z = 0.2 $. These data significantly
increase spectroscopic coverage for very low redshift objects in $ 17 < r_o <
20.75 $ around SAGA hosts, creating a unique data set that places the Local
Group in a wider context. The number of confirmed satellites per system ranges
from zero to nine, and correlates with host galaxy and brightest satellite
luminosities. We find that the number and the luminosities of MW satellites are
consistent with being drawn from the same underlying distribution as SAGA
systems. The majority of confirmed SAGA satellites are star forming, and the
quenched fraction increases as satellite stellar mass and projected radius from
the host galaxy decrease. Overall, the satellite quenched fraction among SAGA
systems is lower than that in the Local Group. We compare the luminosity
functions and radial distributions of SAGA satellites with theoretical
predictions based on cold dark matter simulations and an empirical galaxy-halo
connection model and find that the results are broadly in agreement.
