Sardinia Radio Telescope observations of Local Group dwarf galaxies --
  I. The cases of NGC6822, IC1613, and WLM
  Almost all dwarf galaxies in the Local Group that are not satellites of the
Milky Way or M31, belong to either one of two highly-symmetric planes. It is
still a matter of debate, whether these planar structures are dynamically
stable or whether they only represent a transient alignment. Proper motions, if
they could be measured, could help to discriminate between these scenarios.
Such motions could be determined with multi-epoch Very Long Baseline
Interferometry (VLBI) of sources that show emission from water and methanol at
frequencies of 22 and 6.7 GHz, respectively. We report searches for such
masers. We have mapped three Local Group galaxies, NGC6822, IC1613 and WLM in
the bands covering the water vapor and methanol lines. These systems are
members of the two above mentioned planes of galaxies. We have produced deep
radio continuum (RC) maps and spectral line cubes. The former have been used to
identify star forming regions and to derive global galactic star formation
rates (SFRs). These SFRs turn out to be lower than those determined at other
wavelengths in two of our sources. This indicates that dwarf galaxies may
follow predictions on the RC-SFR relation only in individual regions of
enhanced radio continuum emission, but not when considering the entire optical
body of the sources. No methanol or water maser emission has been confidently
detected, down to line luminosity limits of ~0.004 and 0.01 solar luminosities,
respectively. This finding is consistent with the small sizes, low SFRs and
metallicities of these galaxies.
