Gas and Star Formation in Satellites of Milky Way Analogs

May 2024 • 2024ApJ...966...93J

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

Abstract • 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 $\mathrm{log}{\rho }_{\mathrm{cgm}}/{\rm{g}}\,{\mathrm{cm}}^{-3}\approx -27.3$ . 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.

Links

• PREPRINT http://arxiv.org/abs/2311.02152
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2024ApJ...966...93J
• ELECTR https://doi.org/10.3847/1538-4357/ad3076
• SIMBAD https://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2024ApJ...966...93J
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ad3076/pdf