Spatially-resolved dust properties of the GRB 980425 host galaxy
  Gamma-ray bursts (GRBs) have been proposed as a tool for studying star
formation in the Universe, so it is crucial to investigate whether their host
galaxies and immediate environments are in any way special compared with other
star-forming galaxies. Here we present spatially resolved maps of dust emission
of the host galaxy of the closest known GRB 980425 at z=0.0085 using our new
high-resolution observations from Herschel, Atacama Pathfinder Experiment
(APEX), Atacama Large Millimeter Array (ALMA) and Australia Telescope Compact
Array (ATCA). We modelled the spectral energy distributions of the host and of
the star-forming region displaying the Wolf-Rayet signatures in the spectrum
(WR region), located 800 pc from the GRB position. The host is characterised by
low dust content and a high fraction of UV-visible star formation, similar to
other dwarf galaxies. These galaxies are abundant in the local universe, so it
is not surprising to find a GRB in one of them, assuming the correspondence
between the GRB rate and star formation. The WR region contributes
substantially to the host emission at the far-infrared, millimetre, and radio
wavelengths and we propose that this is a consequence of its high gas density.
If dense environments are also found close to the positions of other GRBs, then
the ISM density should also be considered, along with metallicity, an important
factor influencing whether a given stellar population can produce a GRB.
