NIHAO XV: The environmental impact of the host galaxy on galactic
  satellite and field dwarf galaxies
  We study the impact of the host on dwarf galaxy properties using four new
Milky Way-like, ultra high-resolution simulations, ($N_{\rm part} >10^7$) from
the NIHAO project. We split our sample in satellite ($R<R_{200}$), nearby
($1<R/R_{200}<2.5$), and field ($R>2.5 R_{\rm 200}$) galaxies. Simulated
galaxies from all three groups are in excellent agreement with Local Group
dwarf galaxies in terms of: stellar mass-velocity dispersion, stellar
mass-metallicity relation, star formation histories, and stellar mass
functions. Satellites and nearby galaxies show lower velocity dispersions and
gas fractions compared to field galaxies. While field galaxies follow global
abundance matching relations, satellites and nearby galaxies deviate from them,
showing lower dark matter masses for given stellar mass. The reason for this
deficit in dark matter mass is substantial mass loss experienced by satellites
and $\sim80$\% of the nearby galaxies, while orbiting inside $R_{200}$ at
earlier times. However, both satellites and nearby objects fall back onto the
relation for field galaxies if we use the maximum of their virial mass instead
of the present-day value. This allows us to provide estimates for the peak
masses of observed Local Group galaxies. Finally, using radial velocities,
distances, and the velocity dispersion-stellar mass relation from our
simulations, we derive a metric to distinguish between galaxies harassed by the
central object and unaffected ones. Applying this metric to observed objects we
find that even far away dwarf galaxies like Eri II ($D\approx$ 370 kpc) have a
strong probability ($\approx 83$\%) of having been affected by the Milky Way in
the past. This naturally explains the lack of gas and recent star formation
seen in Eri II.
