Ionized absorbers as evidence for supernova-driven cooling of the lower
  Galactic corona
  We show that the ultraviolet absorption features, newly discovered in HST
spectra, are consistent with being formed in a layer that extends a few kpc
above the disk of the Milky Way. In this interface between the disk and the
Galactic corona, high-metallicity gas ejected from the disk by supernova
feedback can mix efficiently with the virial-temperature coronal material. The
mixing process triggers the cooling of the lower corona down to temperatures
encompassing the characteristic range of the observed absorption features,
producing a net supernova-driven gas accretion onto the disk at a rate of a few
Msun/yr. We speculate that this mechanism explains how the hot-mode of
cosmological accretion feeds star formation in galactic disks.
