Journal Article

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

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

2025

Overview

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, Rvir ∼ 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 MV ∼ −8.0, and include detections of dwarf galaxies as faint as MV ∼ −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 (MV ∼ −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.

• Publisher: IOP Publishing
• Subject: Cold dark matter / Dark energy / Dark matter / Detection limits / Dwarf galaxies / Galaxies / Magellanic clouds / Satellites / Search methods / Spiral galaxies