The SAGA Survey. I. Satellite Galaxy Populations around Eight Milky Way Analogs

By M. Geha, Risa Wechsler, Yao-Yuan Mao, Erik J. Tollerud, B. Weiner, R. Bernstein, Ben Hoyle, S. Marchi, P. J. Marshall, R. Muñoz and 1 more. 2017

183 citations recorded by the source corpus.

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 ( ). We define a Milky Way analog based on K-band luminosity and local environment. Here, we present satellite luminosity functions for eight Milky-Way-analog galaxies between 20 and 40 Mpc. These systems have nearly complete spectroscopic coverage of candidate satellites within the projected host virial radius down to 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 5 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.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d56c014e5ecef859b3bd95c71f696a37d0a505de

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Citations in the corpus

The Early Data Release of the Dark Energy Spectroscopic Instrument (2023, methodology): “The target space was constrained using cuts on surface brightness and color adapted from the SAGA Survey ( Geha et al. 2017; Mao et al. 2021 ) with minor adjustments.”
Illuminating Low Surface Brightness Galaxies with the Hyper Suprime-Cam Survey (2017, background): “This color box is conservative with respect to what we expect from red and blue LSBGs (e.g., Román & Trujillo 2017a,b; Geha et al. 2017), as well as with respect to reasonable assumptions about stellar populations (as we show in Section 4.1).”
Quenching and ram pressure stripping of simulated Milky Way satellite galaxies (2017, background): “The Auriga satellite systems are quite different from the satellite systems of the SAGA survey (Geha et al. 2017) that finds uniformly star forming satellite systems in 8 MW analog galaxies down to a satellite luminosity of Mr = −12.3.”