The globular cluster system of NGC 1316 (Fornax A)

¹ Departamento de Astronomía y Astrofísica, P. Universidad Católica de Chile, Casilla 306, Santiago, Chile e-mail: mgomez@astro.puc.cl,linfante@astro.puc.cl
² Sternwarte der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
³ Departamento de Física, Universidad de Concepción, Casilla 4009, Concepción, Chile e-mail: tom@coma.cfm.udec.cl
⁴ Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching bei München, Germany e-mail: georg@mpa-garching.mpg.de

Corresponding author: M. Gómez, mgomez@astro.puc.cl

Received: 22 November 2000
Accepted: 22 March 2001

Abstract

We have studied the Globular Cluster System of the merger galaxy NGC 1316 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 , 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 NGC 1316 of only , which confirms with a larger field a previous finding by Grillmair et al. ([CITE]). Assuming a "normal"S_N of ~4 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 NGC 1316 derived by Kuntschner & Davies ([CITE]) and Mackie & Fabbiano ([CITE]). By fitting t₅ functions to the Globular Cluster Luminosity Function (GCLF), we derived the following turnover magnitudes: , and . They support that NGC 1316, in spite of its outlying location, is at the same distance as the core of the Fornax cluster.