The radial distribution of core-collapse supernovae in spiral host
  galaxies
  With the goal of providing constraints on the nature of the progenitors of
core-collapse supernovae, we compare their radial distribution within their
spiral host galaxies with the distributions of stars and ionized gas in the
spiral disks. The normalized radial distribution of all CCSNe is consistent
with an exponential law, with a possible depletion of CCSNe within one-fifth of
the isophotal radius. The scale length of the distribution of type II SNe
appears to be significantly larger than that of the stellar disks of their host
galaxies, but consistent with the scale lengths of Freeman disks. SNe Ib/c have
a significantly smaller scale length than SNe II, with little difference
between types Ib and Ic. The radial distribution of type Ib/c SNe is more
centrally concentrated than that of the stars in a Freeman disk, but is similar
to the stellar disk distribution that we infer for the host galaxies. The scale
length of the CCSN radial distribution shows no significant correlation with
the host galaxy morphological type, or the presence of bars. However, low
luminosity as well as inclined hosts have a less concentrated distribution of
CCSNe, which are probably a consequence of metallicity and selection effects,
respectively. The exponential distribution of CCSNe shows a scale length
consistent with that of the ionized gas confirming the generally accepted
hypothesis that the progenitors of these SNe are young massive stars. Given the
lack of correlation of the normalized radial distances of CCSNe with the
morphological type of the host galaxy, we conclude that the more concentrated
distribution of SNe Ib/c relative to SNe II must arise from the higher
metallicity of their progenitors or possibly from a shallower initial mass
function in the inner regions of spirals.
