How runaway stars boost galactic outflows
  Roughly ten per cent of OB stars are kicked out of their natal clusters
before ending their life as supernovae. These so-called runaway stars can
travel hundreds of parsecs into the low-density interstellar medium, where
momentum and energy from stellar feedback is efficiently deposited. In this
work we explore how this mechanism affects large scale properties of the
galaxy, such as outflows. To do so we use a new model which treats OB stars and
their associated feedback processes on a star-by-star basis. With this model we
compare two hydrodynamical simulations of Milky Way-like galaxies, one where we
include runaways, and one where we ignore them. Including runaway stars leads
to twice as many supernovae explosions in regions with gas densities ranging
from 1e-5 cm^-3 to 1e-3 cm^-3. This results in more efficient heating of the
inter-arm regions, and drives strong galactic winds with mass loading factors
boosted by up to one order of magnitude. These outflows produce a more massive
and extended multi-phase circumgalactic medium, as well as a population of
dense clouds in the halo. Conversely, since less energy and momentum is
released in the dense star forming regions, the cold phase of the interstellar
medium is less disturbed by feedback effects.
