Fundamental relations of early-type galaxies in the Antlia cluster

CALDERÓN, J. P.; BASSINO, L. P.; CELLONE, S. A.; CASO, J. P.; RICHTLER, T.; GOMEZ, M.

Santiago

Workshop; Deconstructing Galaxies: Structure and Morphology in the Era of Large Surveys (ESO Workshop); 2013

European Southern Observatory (ESO)

The Antlia Cluster is the third nearest populous galaxy cluster, after Fornax and Virgo, at a distance of approx 35 Mpc. The first study previous to our present project was the photographic catalogue by Ferguson and Sandage (1990, FS90), which identified 375 galaxies. Due to its proximity and large population, the Antlia cluster is a quite interesting target to study the galaxies´ structure and morphology, with the final aim to contribute to a better understanding of the origin and evolution of galaxies.    The observational material used for this study consists of CCD images of  four MOSAIC fields (36´ x 36´) in R (Washington) and C (Kron-Cousins) filters, and GEMINI/GMOS spectra to confirm membership. Surface photometry was erformed for about 240 early-type Antlia galaxies, by means of IRAF tasks plus our own scripts. We fitted Sersic models to their surface brightness profiles and characterized the galaxy sample according to total magnitudes and colours, effective radius, effective surface brightness, and Sersic index N. In all cases, we fitted one or two components, depending on the residuals systematic behavior. Out of the total sample, 60% of the galaxies had been catalogued by FS90, while the rest are newly discovered galaxies.    Finally, we built the fundamental relations that involve the photometric and structural parameters for the early-type galaxies, i.e. colour vs. magnitude, effective surface brightness vs. effective radius, effective surface brightness vs. magnitude, the respective relations with the N index, etc. From them and the comparison with the results for other clusters, we show that in some cases the dwarf galaxies seem to follow a different sequence than their brighter counterparts.