The globular cluster system of NGC?1316 - I. Wide-field photometry in the Washington system

摘要

Context. NGC?1316 (Fornax A) is a prominent merger remnant in the outskirts of the Fornax cluster. The bulge stellar population of NGC?1316 has a strong intermediate-age component. Studies of its globular cluster system may help to further refine its probably complex star formation history. Aims. The cluster system has not yet been studied in its entirety. We therefore present a wide-field study of the globular cluster system of NGC?1316, investigating its properties in relation to the global morphology of NGC?1316. Methods. We used the MOSAIC II camera at the 4-m Blanco telescope at CTIO in the filters Washington C and Harris R. We identified globular cluster candidates and studied their color distribution and the structural properties of the system. In an appendix, we also remark on the morphology, present color maps, and present new models for the brightness and color profiles of the galaxy. Results. The cluster system is well confined to the optically visible outer contours of NGC?1316. There are about 640?cluster candidates down to R?=?24?mag. The color distribution of the entire sample is unimodal, but the color distribution of bright subsamples in the bulge shows two peaks that, compared with theoretical Washington colors with solar metallicity, correspond to ages of about 2?Gyr and 0.8?Gyr, respectively. We also find a significant population of clusters in the color range 0.8?