We have performed a spectroscopic study of globular clusters ( GCs ) in the nearest giant elliptical NGC 5128 using the 2dF facility at the Anglo-Australian telescope .
We obtained integrated optical spectra for a total of 254 GCs , 79 of which are newly confirmed on the basis of their radial velocities and spectra .
In addition , we obtained an integrated spectrum of the galaxy starlight along the southern major axis .
We derive an empirical metallicity distribution function ( MDF ) for 207 GCs ( \sim 14 \% of the estimated total GC system ) based upon Milky Way GCs .
This MDF is multimodal at high statistical significance with peaks at [ Z/H ] \sim - 1.3 and -0.5 .
A comparison between the GC MDF and that of the stellar halo at 20 kpc ( \sim 4 R _ { e } ) reveals close coincidence at the metal-rich ends of the distributions .
However , an inner 8 kpc stellar MDF shows a clear excess of metal-rich stars when compared to the GCs .
We compare a higher S/N subsample ( 147 GCs ) with two stellar population models which include non-solar abundance ratio corrections .
The vast majority of our sample ( \sim 90 \% ) appears old , with ages similar to the Milky Way GC system .
There is evidence for a population of intermediate-age ( \sim 4 - 8 Gy ) GCs ( \leq 15 \% of the sample ) which are on average more metal-rich than the old GCs .
We also identify at least one younger cluster ( \sim 1 - 2 Gy ) in the central regions of the galaxy .
Our observations are consistent with a picture where NGC 5128 has undergone at least two mergers and/or interactions involving star formation and limited GC formation since z = 1 , however the effect of non-canonical hot stellar populations on the integrated spectra of GCs remains an outstanding uncertainty in our GC age estimates .