2017MNRAS.469.3444T

New wide-field ugriz Dark Energy Camera observations centred on the nearby giant elliptical galaxy NGC 5128 covering ∼21 deg² are used to compile a new catalogue of ∼3200 globular clusters (GCs). We report 2404 newly identified candidates, including the vast majority within ∼140 kpc of NGC 5128. We find evidence for a transition at a galactocentric radius of R_gc ≃ 55 kpc from GCs 'intrinsic' to NGC 5128 to those likely to have been accreted from dwarf galaxies or that may transition to the intragroup medium of the Centaurus A galaxy group. We fit power-law surface number density profiles of the form Σ_N, R_ gc_∝R_ gc_^Γand find that inside the transition radius, the red GCs are more centrally concentrated than the blue, with Γ_inner, red_ ≃ -1.78 and Γ_inner, blue_ ≃ -1.40, respectively. Outside this region both profiles flatten, more dramatically for the red GCs (Γ_outer, red_ ≃ -0.33) compared to the blue (Γ_outer, blue_ ≃ -0.61), although the former is more likely to suffer contamination by background sources. The median (g - z)₀ = 1.27 mag colour of the inner red population is consistent with arising from the amalgamation of two giant galaxies each less luminous than present-day NGC 5128. Both inwards and outwards of the transition radius, we find the fraction of blue GCs to dominate over the red GCs, indicating a lively history of minor mergers. Assuming the blue GCs to originate primarily in dwarf galaxies, we model the population required to explain them, while remaining consistent with NGC 5128's present-day spheroid luminosity. We find that several dozen dwarfs of luminosities L_dw, V_ ≃ 10^6–9.3 L_V, ☉_, following a Schechter luminosity function with a faint-end slope of -1.50 <= α <= -1.25 is favoured, many of which may have already been disrupted in NGC 5128's tidal field.