  Broad-line Ic supernovae (SNe Ic-BL) are a very rare class of core-collapse
supernovae exhibiting high ejecta velocities and high kinetic energies. They
are the only type of SNe that accompany long gamma-ray burst (GRB) explosions.
Systematic differences found in the spectra of SNe Ic-BL with and without GRBs
(GRB-SNe and SNe Ic-BL, respectively) suggest that either the progenitor or/and
explosion mechanism of SNe Ic-BL with and without a GRB differ, or the
difference could be only due to the viewing angle of the observer with respect
to the orientation of the collimated explosion. We present the systematic
comparison of the host galaxies of broad-lined SNe Ic with and without a
detected GRB, the latter being detected in untargeted surveys, with the aim to
find out whether there are any systematic differences between the environments
in which these two classes of SNe preferentially explode. We study photometric
properties of the host galaxies of a sample of 8 GRB-SNe and a sample of 28 SNe
Ic-BL at z < 0.2. The two galaxy samples have indistinguishable luminosity and
proper size distribution. We find indications that GRB-SNe on average occur
closer to the centres of their host galaxies, i.e. the samples have a different
distribution of projected offsets, normalized by the galaxy sizes. In addition
we compare gas-phase metallicities of the GRB-SNe and SNe Ic-BL host samples
and find that a larger fraction of super-solar metallicity hosts are found
among the SNe Ic-BL without a GRB. Our results are indicative of a genuine
difference between the two types of explosions and suggest that the viewing
angle is not the main source of difference in the spectra of the two classes.
We discuss the implications our results have on our understanding of
progenitors of SNe Ic-BL with and without a GRB.
