All-sky census of Galactic high-latitude molecular intermediate-velocity
  clouds
  The HI halo clouds of the Milky Way, and in particular the
intermediate-velocity clouds (IVCs), are thought to be connected to Galactic
fountain processes. Observations of fountain clouds are important for
understanding the role of matter recycling and accretion onto the Galactic disk
and subsequent star formation. Here, we quantify the amount of molecular gas in
the Galactic halo. We focus on the rare class of molecular IVCs (MIVCs) and
search for new objects. The HI-FIR correlation was studied across the entire
northern and southern Galactic hemispheres at Galactic latitudes $|b|>20^\circ$
to determine the amount and distribution of molecular gas in IVCs. We used the
most recent large-scale HI and FIR data, the Effelsberg Bonn-HI Survey, the
Parkes Galactic All-Sky Survey, and the Planck FIR surveys. We present a
catalogue of 239 MIVC candidates on the northern and southern Galactic
hemispheres. Among these candidates, all previously known MIVCs are recovered
except for one single source. The frequency of candidates differs significantly
between the northern and southern Galactic hemispheres and between negative and
positive LSR velocities as well. In our approach we analyse the local Galactic
environment. Extrapolating our results to the entire Galaxy, the global inflow
of atomic and molecular IVC gas onto the Milky Way may account for the major
fraction of the gaseous mass that is required to sustain the current Galactic
star formation rate.
