@article{1536457cea0047348b2ca1bc00740a62,
title = "The SAGA Survey. I. Satellite Galaxy Populations around Eight Milky Way Analogs",
abstract = "We present the survey strategy and early results of the {"}Satellites Around Galactic Analogs{"} (SAGA) Survey. The SAGA Surveys 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 (Mr > -12.3). We define a Milky Way analog based on K-band luminosity and local environment. Here, we present satellite luminosity functions for eight Milky-Wayanalog galaxies between 20 and 40 Mpc. These systems have nearly complete spectroscopic coverage of candidate satellites within the projected host virial radius down to ro > 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 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 Ways satellite galaxies.",
keywords = "galaxies: dwarf, galaxies: halos, galaxies: luminosity function, mass function, galaxies: structure, Local Group",
author = "Marla Geha and Wechsler, {Risa H.} and Mao, {Yao Yuan} and Tollerud, {Erik J.} and Benjamin Weiner and Rebecca Bernstein and Ben Hoyle and Sebastian Marchi and Marshall, {Phil J.} and Ricardo Mu{\~n}oz and Yu Lu",
note = "Funding Information: We thank Carlos Cunha, Claire Dickey, Yashar Hezaveh, Vikas Bhetanabhotla, Emily Sandford, Jeremy Tinker, and Andrew Wetzel for helpful discussions. We thank Michael Blanton for his work on the NASA-Sloan Atlas, which was critical to the start of this project. R.H.W. thanks her Physics 16 students for their contributions to visual classification at an early stage of the project. This work was supported by NSF collaborative grant AST-1517148 awarded to M.G. and R.H. W. M.G. thanks the John S.Guggenheim Foundation for generous support. Y.-Y.M. is supported by the Samuel P.Langley PITT PACC Postdoctoral Fellowship and was supported by the Weiland Family Stanford Graduate Fellowship. Support for E.J.T. was provided by a Giacconi Fellowship and by NASA through Hubble Fellowship grant no. 51316.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. Part of this work uses the computational resources at the SLAC National Accelerator Laboratory, a U.S. Department of Energy Office; R.H.W., Y.-Y.M., and Y.L. thank the SLAC computational team for their consistent support. Observations reported here were obtained in part at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. GAMA is a joint European–Australasian project based around a spectroscopic campaign using the Anglo-Australian Telescope. The GAMA input catalog is based on data taken from the Sloan Digital Sky Survey and the UKIRT Infrared Deep Sky Survey. GAMA is funded by the STFC (UK), the ARC (Australia), the AAO, and the participating institutions. Publisher Copyright: {\textcopyright} 2017. The American Astronomical Society. All rights reserved.",
year = "2017",
month = sep,
day = "20",
doi = "10.3847/1538-4357/aa8626",
language = "English (US)",
volume = "847",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",
}