MusE GAs FLOw and Wind (MEGAFLOW) III: galactic wind properties using
  background quasars
  We present results from our on-going MusE GAs FLOw and Wind (MEGAFLOW)
survey, which consists of 22 quasar lines-of-sight, each observed with the
integral field unit (IFU) MUSE and the UVES spectrograph at the ESO Very Large
Telescopes (VLT). The goals of this survey are to study the properties of the
circum-galactic medium around $z\sim1$ star-forming galaxies. The
absorption-line selected survey consists of 79 strong \MgII\ absorbers (with
rest-frame equivalent width (REW)$\gtrsim$0.3\AA) and, currently, 86 associated
galaxies within 100 projected~kpc of the quasar with stellar masses ($M_\star$)
from $10^9$ to $10^{11}$ \msun. We find that the cool halo gas traced by \MgII\
is not isotropically distributed around these galaxies, as we show the strong
bi-modal distribution in the azimuthal angle of the apparent location of the
quasar with respect to the galaxy major-axis. This supports a scenario in which
outflows are bi-conical in nature and co-exist with a coplanar gaseous
structure extending at least up to 60 to 80 kpc. Assuming that absorbers near
the minor axis probe outflows, the current MEGAFLOW sample allowed us to select
26 galaxy-quasar pairs suitable for studying winds. From this sample, using a
simple geometrical model, we find that the outflow velocity only exceeds the
escape velocity when $M_{\star}\lesssim 4\times10^9$~\msun, implying the cool
material is likely to fall back except in the smallest halos. Finally, we find
that the mass loading factor $\eta$, the ratio between the ejected mass rate
and the star formation rate (SFR), appears to be roughly constant with respect
to the galaxy mass.
