Gas and Star Formation in Satellites of Milky Way Analogs

Michael G. Jones, David J. Sand, Ananthan Karunakaran, Kristine Spekkens, Kyle A. Oman, Paul Bennet, Gurtina Besla, Denija Crnojević, Jean Charles Cuillandre, Catherine E. Fielder, Stephen Gwyn, Burçin Mutlu-Pakdil

Research output: Contribution to journalArticlepeer-review


We have imaged the entirety of eight (plus one partial) Milky Way (MW)-like satellite systems, a total of 42 (45) satellites, from the Satellites Around Galactic Analogs II catalog in both Hα and H i with the Canada-France-Hawaii Telescope and the Jansky Very Large Array. In these eight systems we have identified four cases where a satellite appears to be currently undergoing ram pressure stripping (RPS) as its H i gas collides with the circumgalactic medium (CGM) of its host. We also see a clear suppression of gas fraction (M HI/M *) with decreasing (projected) satellite-host separation—to our knowledge, the first time this has been observed in a sample of MW-like systems. Comparisons to the Auriga, A Project Of Simulating The Local Environment, and TNG50 cosmological zoom-in simulations show consistent global behavior, but they systematically underpredict gas fractions across all satellites by roughly 0.5 dex. Using a simplistic RPS model, we estimate the average peak CGM density that satellites in these systems have encountered to be log ρ cgm / g cm − 3 ≈ − 27.3 . Furthermore, we see tentative evidence that these satellites are following a specific star formation rate to gas fraction relation that is distinct from field galaxies. Finally, we detect one new gas-rich satellite in the UGC 903 system with an optical size and surface brightness meeting the standard criteria to be considered an ultra-diffuse galaxy.

Original languageEnglish (US)
Article number93
JournalAstrophysical Journal
Issue number1
StatePublished - May 1 2024

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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