Efficiency of gas cooling and accretion at the disc-corona interface
  In star-forming galaxies, stellar feedback can have a dual effect on the
circumgalactic medium both suppressing and stimulating gas accretion. The
trigger of gas accretion can be caused by disc material ejected into the halo
in the form of fountain clouds and by its interaction with the surrounding hot
corona. Indeed, at the disc-corona interface, the mixing between the
cold/metal-rich disc gas (T <~ 10^4 K) and the hot coronal gas (T >~ 10^6 K)
can dramatically reduce the cooling time of a portion of the corona and produce
its condensation and accretion. We studied the interaction between fountain
clouds and corona in different galactic environments through parsec-scale
hydrodynamical simulations, including the presence of thermal conduction, a key
mechanism that influences gas condensation. Our simulations showed that the
coronal gas condensation strongly depends on the galactic environment, in
particular it is less efficient for increasing virial temperature/mass of the
haloes where galaxies reside and it is fully ineffective for objects with
virial masses larger than 10^13 Msun. This result implies that the coronal gas
cools down quickly in haloes with low-intermediate virial mass (Mvir <~ 3 x
10^12 Msun) but the ability to cool the corona decreases going from late-type
to early-type disc galaxies, potentially leading to the switching off of
accretion and the quenching of star formation in massive systems.
