The Case for Strangulation in Low-Mass Hosts: DDO 113
  We investigate the case for environmental quenching of the Fornax-mass
satellite DDO 113, which lies only 9 kpc in projection from its host, the
Large-Magellanic-Cloud-mass galaxy NGC 4214. DDO 113 was quenched about 1 Gyr
ago and is virtually gas-free, while analogs in the field are predominantly
star-forming and gas-rich. We use deep imaging obtained with the Large
Binocular Telescope to show that DDO 113 exhibits no evidence of tidal
disruption to a surface brightness of $\mu_V\sim29$ mag $\text{arcsec}^{-2}$,
based on both unresolved emission and resolved stars. Mass-analogs of DDO 113
in Illustris-1 with similar hosts, small projected separations, and no
significant tidal stripping first fell into their host halo 2--6 Gyr ago,
showing that tidal features (or lack thereof) can be used to constrain infall
times in systems where there are few other constraints on the orbit of the
satellite. With the infall time setting the clock for environmental quenching
mechanisms, we investigate the plausibility of several such mechanisms. We find
that strangulation, the cessation of cold gas inflows, is likely the dominant
quenching mechanism for DDO 113, requiring a time-averaged mass-loading factor
of $\eta=6-11$ for star-formation-driven outflows that is consistent with
theoretical and observational constraints. Motivated by recent numerical work,
we connect DDO 113's strangulation to the presence of a cool circumgalactic
medium (CGM) around NGC 4214. This discovery shows that the CGM of low-mass
galaxies can affect their satellites significantly and motivates further work
on understanding the baryon cycle in low-mass galaxies.
