The NGC 3109 Satellite System: The First Systematic Resolved Search for Dwarf Galaxies Around an SMC-mass Host

August 2025 • 2025ApJ...989...21D

Authors • Doliva-Dolinsky, Amandine • Mutlu-Pakdil, Burçin • Crnojević, Denija • Anbajagane, Dhayaa • Carlin, Jeffrey L. • Medoff, Jonah • Sand, David J. • Tollerud, Erik • Lim, Sungsoon • Bennet, Paul • Drlica-Wagner, Alex • Fielder, Catherine E. • Hargis, Jonathan R. • Herron, Kai • Hunter, Laura Congreve • Jones, Michael G. • Karunakaran, Ananthan • Peter, Annika H. G. • Romanowsky, Aaron J. • Spekkens, Kristine • Strader, Jay • Willman, Beth • Carballo-Bello, Julio A. • Cerny, William • Chaturvedi, Astha • Kallivayalil, Nitya • Martínez-Vázquez, Clara E. • Medina, Gustavo E. • Noël, Noelia E. D. • Pace, Andrew B. • Riley, Alex H. • Sakowska, Joanna D. • Smercina, Adam • Vivas, Kathy • Adamów, Monika • Bom, Clecio R. • Choi, Yumi • Ferguson, Peter S. • Navabi, Mahdieh • Zenteno, Alfredo • Delve Collaboration

Abstract • We report the results of the deepest search to date for dwarf galaxies around NGC 3109, a barred spiral galaxy with a mass similar to that of the Small Magellanic Cloud (SMC), using a semiautomated search method. Using the Dark Energy Camera, we survey a region covering a projected distance of ∼70 kpc of NGC 3109 (D = 1.3 Mpc, R_vir ∼ 90 kpc, M ∼ 10⁸M_*) as part of the MADCASH and DELVE-DEEP programs. We introduce a newly developed semiresolved search method, used alongside a resolved search, to identify crowded dwarf galaxies around NGC 3109. Using both approaches, we successfully recover the known satellites Antlia and Antlia B. We identified a promising candidate, which was later confirmed to be a background dwarf through deep follow-up observations. Our detection limits are well defined, with the sample ∼80% complete down to M_V ∼ −8.0, and include detections of dwarf galaxies as faint as M_V ∼ −6.0. This is the first comprehensive study of a satellite system through resolved stars around an SMC mass host. Our results show that NGC 3109 has more bright (M_V ∼ −9.0) satellites than the mean predictions from cold dark matter models, but well within the host-to-host scatter. A larger sample of LMC/SMC-mass hosts is needed to test whether or not the observations are consistent with current model expectations.

Links

• SIMBAD https://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2025ApJ...989...21D
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ade9b8/pdf
• PREPRINT http://arxiv.org/abs/2505.05570
• DATA https://archive.gemini.edu/searchform/publication=2025ApJ...989...21D
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2025ApJ...989...21D
• DATA https://doi.org/10.5281/zenodo.15631111
• ELECTR https://doi.org/10.3847/1538-4357/ade9b8