ID-MAGE. II. The Star-forming Satellites of Low-mass Hosts

Abstract

Abstract We present the first results of the ongoing Identifying Dwarfs of Magellanic Cloud Analog GalaxiEs (ID-MAGE) survey. This includes new velocities of 78 satellite candidates identified around 35 nearby LMC- and SMC-mass hosts ( D = 4–10 Mpc). Using new Green Bank Telescope H i observations, new optical long-slit spectroscopy from SALT and MDM 2.4 m, and Dark Energy Spectroscopic Instrument DR1, we find six are velocity-confirmed satellite galaxies (6.5 × 10 5 ≤ M ⋆ / M ⊙ ≤ 1.5 × 10 7 ) and 72 are background galaxies. Our results underscore the ability of spectroscopic follow-up to effectively separate satellites from background galaxies. Including the six newly velocity-confirmed satellites and the 19 satellites confirmed in the literature, the ID-MAGE hosts have a combined total of 25 confirmed satellites. This confirmed satellite sample includes the complete satellite populations of three hosts (UGC 04426: zero satellites; UGC 08201: zero satellites; NGC 3432: four satellites), which we compare to simulations and known satellite systems from previous systematic searches around low-mass hosts. Our confirmed satellite sample is nearly complete for the most massive satellites ( M ⋆ > 10 7 M ⊙ ). We find these 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 Milky Way–analog satellites in the same stellar mass range (10 7 M ⊙ < M ⋆ < 10 8 M ⊙ ). This demonstrates the impact that low-mass galaxies have on the evolution of their satellites.