  We deduce the globular cluster formation history of the nearby elliptical NGC
5128 by using a phenomenological chemical enrichment model to reproduce its
observed metallicity distribution function (MDF). We derive the observed MDF
using recently obtained U and B photometry of the NGC 5128 GC system, with
(U-B) used as the metallicity indicator. We test whether the observed MDF can
be reproduced using a single starburst at high redshift followed by passive
evolution (monolithic scenario). Our results strongly indicate that this
scenario is incapable of reproducing the observed MDF of the NGC 5128 GC
system. At least one more major starburst is required. A persistent feature of
our best-fit models is a strong GC formation episode in the first 1-2 Gyrs,
followed by a second formation episode typically after 10-12 Gyrs. Roughly
one-third of the stellar mass in the GC system is created in this late
starburst, producing clusters that are potentially less than 1 Gyr old.
Although we do not have adequate resolution in the model or in the observed MDF
to make a reliable claim about the possibility of additional GC formation
episodes, our results suggest that the GCs in this galaxy did not form solely
in a monolithic collapse and seem to support observational evidence which
indicates that NGC 5128 is a merger remnant.

Astrophysics