The globular cluster system of NGC 1316 (Fornax A)

We have studied the Globular Cluster System of the merger galaxy NGC1316 in Fornax, using CCD BVI photometry. A clear bimodality is not detected from the broadband colours. However, dividing the sample into red (presumably metal-rich) and blue (metal-poor) subpopulations at B-I = 1.75, we find that they follow strikingly different angular distributions. The red clusters show a strong correlation with the galaxy elongation, but the blue ones are circularly distributed. No systematic difference is seen in their radial profile and both are equally concentrated. We derive an astonishingly low Specific Frequency for NGC1316 of only S-N = 0.9, which confirms with a larger field a previous finding by Grillmair et al. (1999). Assuming a normal S-N of similar to4 for early-type galaxies, we use stellar population synthesis models to estimate in 2 Gyr the age of this galaxy, if an intermediate-age population were to explain the low S-N we observe. This value agrees with the luminosity-weighted mean age of NGC1316 derived by Kuntschner & Davies (1998) and Mackie & Fabbiano (1998). By fitting t(5) functions to the Globular Cluster Luminosity Function (GCLF), we derived the following turnover magnitudes: B = 24.69 +/- 0.15, V = 23.87 +/- 0.20 and I = 22.72 +/- 0.14. They support that NGC1316, in spite of its outlying location, is at the same distance as the core of the Fornax cluster.