The Production Rate of SN Ia Events in Globular Clusters
  In globular clusters, dynamical evolution produces luminous X-ray emitting
binaries at a rate about 200 times greater than in the field. If globular
clusters also produce SNe Ia at a high rate, it would account for much of the
SN Ia events in early type galaxies and provide insight into their formation.
Here we use archival HST images of nearby galaxies that have hosted SNe Ia to
examine the rate at which globular clusters produce these events. The location
of the SN Ia is registered on an HST image obtained before the event or after
the supernova faded. Of the 36 nearby galaxies examined, 21 had sufficiently
good data to search for globular cluster hosts. None of the 21 supernovae have
a definite globular cluster counterpart, although there are some ambiguous
cases. This places an upper limit to the enhancement rate of SN Ia production
in globular clusters of about 42 at the 95% confidence level, which is an order
of magnitude lower than the enhancement rate for luminous X-ray binaries. Even
if all of the ambiguous cases are considered as having a globular cluster
counterpart, the upper bound for the enhancement rate is 82 at the 95%
confidence level, excluding an enhancement rate of 200. Barring unforeseen
selection effects, we conclude that globular clusters are not responsible for
producing a significant fraction of the SN Ia events in early-type galaxies.
