Environmental Quenching of Low-Mass Field Galaxies
  In the local Universe, there is a strong division in the star-forming
properties of low-mass galaxies, with star formation largely ubiquitous amongst
the field population while satellite systems are predominantly quenched. This
dichotomy implies that environmental processes play the dominant role in
suppressing star formation within this low-mass regime (${M}_{\star} \sim
10^{5.5-8}~{\rm M}_{\odot}$). As shown by observations of the Local Volume,
however, there is a non-negligible population of passive systems in the field,
which challenges our understanding of quenching at low masses. By applying the
satellite quenching models of Fillingham et al. (2015) to subhalo populations
in the Exploring the Local Volume In Simulations (ELVIS) suite, we investigate
the role of environmental processes in quenching star formation within the
nearby field. Using model parameters that reproduce the satellite quenched
fraction in the Local Group, we predict a quenched fraction -- due solely to
environmental effects -- of $\sim 0.52 \pm 0.26$ within $1< R/R_{\rm vir} < 2$
of the Milky Way and M31. This is in good agreement with current observations
of the Local Volume and suggests that the majority of the passive field systems
observed at these distances are quenched via environmental mechanisms. Beyond
$2~R_{\rm vir}$, however, dwarf galaxy quenching becomes difficult to explain
through an interaction with either the Milky Way or M31, such that more
isolated, field dwarfs may be self-quenched as a result of star-formation
feedback.
