http://arxiv.org/abs/1705.06743
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. This includes 14 satellite galaxies meeting our formal criteria around our complete host systems, and an additional 11 in incompletely surveyed hosts or below our formal magnitude limit. Combined with 13 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. Unlike the Milky Way satellites, 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.
M. Geha, R. Wechsler, Y. Mao, et. al.
Mon, 22 May 17
46/51
Comments: 22 pages, 19 figures, 2 tables. Survey website: this http URL