English

ID-MAGE II: The Star Forming Satellites of Low-Mass Hosts

Astrophysics of Galaxies 2026-03-23 v2

Abstract

We present results from our ongoing campaign to follow up the satellite candidates from the Identifying Dwarfs of MC Analog GalaxiEs (ID-MAGE) survey. Previously, we published a list of 355 unresolved satellite candidates identified around 36~nearby LMC- and SMC-mass hosts (D==4-10~Mpc). We present the velocities of 83 satellite candidates from new Green Bank Telescope \hi\ observations, optical long-slit spectra, and the Dark Energy Survey Instrument Data Release 1. Based on their velocities, we identify six candidates as probable satellite galaxies (6.5×105M/M1.5×1076.5\times10^5\leq M_\star/M_\odot\leq1.5\times10^7) and 77 as background galaxies. Our results underscore the ability of spectroscopic follow-up to effectively separate satellites from background galaxies. Using the refined sample, we update our previously derived estimates for the average satellite population per host and find 1.7±\pm0.7 (1.0±\pm0.3) satellites per LMC-mass (SMC-mass) host. Our current satellite sample includes 25 galaxies confirmed by distances or velocities. This set includes the complete satellite populations of three hosts (UGC~04422: zero satellites, UGC~08201: zero satellites, NGC~3432: four satellites), which we compare to simulations and known satellite systems from the literature. Our sample is nearly complete for the most massive satellites (M>107 M_\star > 10^7~M_\odot). We find these massive satellites have a quenched fraction of 10--25\%, placing them between the <<5\% quenched fraction of isolated galaxies and the 40--70\% quenched fraction of MW-analog satellites with 107 M<10^7~M_\odot < M<108 M_\star < 10^8~M_\odot. This demonstrates the impact that low-mass galaxies have on the evolution of their satellites.

Keywords

Cite

@article{arxiv.2603.18973,
  title  = {ID-MAGE II: The Star Forming Satellites of Low-Mass Hosts},
  author = {Laura Congreve Hunter and Burçin Mutlu-Pakdil and Michael B. Farnell and David J. Sand and Paul Bennet and Sasha N. Campana and Jeffrey L. Carlin and Denija Crnojević and Amandine Doliva-Dolinsky and Emmanuel Durodola and Michael G. Jones and Donghyeon J. Khim and Laurella Marin and Ricardo J. Mendez and Deepthi S. Prabhu and Kristine Spekkens and Dennis Zaritsky},
  journal= {arXiv preprint arXiv:2603.18973},
  year   = {2026}
}

Comments

19 pages, 8 page appendix