The globular cluster systems of NGC 3258 and NGC 3268 in the Antlia cluster

Abstract

The Antlia galaxy cluster is the third nearest galaxy cluster after Virgo and Fornax. We used the wide-field MOSAIC camera of the 4-m CTIO telescope to search in the brightest cluster galaxies for globular cluster systems, which were detected in the two larger ellipticals - NGC 3258 and NGC 3268. These galaxies each contain several thousand clusters; NGC 3258 more than NGC 3268. The color distributions of the globular cluster systems are clearly bimodal. The peak colors agree with those of other ellipticals. The radial number density profiles of the globular cluster systems are indistinguishable for the two galaxies and no difference in the distribution of red and blue clusters - as observed in other elliptical galaxies - can be seen. The light profile of NGC 3268 appears to be similar to that of NGC 1399, the central galaxy of the Fornax cluster. NGC 3258 has a light profile which is steeper at large radii. Both galaxies exhibit color gradients, becoming bluer outwards. In NGC 3268, the color and morphology in the inner 3″ indicate the presence of an inner dusty disk. The globular cluster systems closely trace the galaxy light in the studied radial regime. The elongation of the cluster systems of both galaxies is approximately aligned at large radii with the connecting axis of the two galaxies. We find specific frequencies within a radial range of 4′ of S<SUB>N</SUB> - 3.0 ± 2.0 for NGC 3268 and S<SUB>N</SUB> = 6.0 ± 2.5 for NGC 3258. As a byproduct resulting from surveying our wide-field frames, we describe a strange absorption feature in the Antlia spiral galaxy NGC 3269, which we argue might be a tiny galactic dust cloud projected onto NGC 3269.