Early-type galaxies in the Antlia Cluster: global properties

Abstract

We presentan extension of our previous research on the early-type galaxy population ofthe Antlia cluster (d ~ 35 Mpc), achieving a total coverage of ~ 2.6 deg x degand performing surface photometry for ~300 galaxies, 130 of which are newuncatalogued ones. Such new galaxies mainly fall in the low surface brightness(LSB) regime, but there are also some lenticulars (S0) which support theexistence of unique functions that connect bright and dwarf galaxies in thescaling relations. We analyse the projected spatial distribution of galaxies upto a distance of ~800 kpc from NGC 3268, the adopted centre, as well as theradial velocity distribution and the correlation between galaxy colour andeffective radius with the projected spatial distribution. We also obtain theluminosity function of the early-type galaxies and the distribution of stellarmasses using the T1-band magnitudes and adopted mass-luminosity ratios.Additionally, we correlate the central galaxy distribution with an X-rayemission map from the literature. Based on the analysis of the radialvelocities and galaxy colour distributions, we find that galaxies redder thanthe colour-magnitude relation (CMR) have a velocity distribution stronglyconcentrated towards the values of the dominant galaxies and are homogeneouslydistributed throughout the cluster. Those bluer than the CMR, in turn, have amuch more extended radial velocity distribution and are concentrated towardsthe centre of the cluster. We also identify 12 candidates to ultra diffuse galaxies(UDG), that seem to be split into two families, and speculate about theirorigins in the context of the cluster structure.