The cluster of galaxies LCDCS-S001 - II. r′ and i′ photometry, morphological analysis and improved kinematic parameters

Abstract

We present photometric parameters of the galaxies in the direction of the galaxy cluster LCDCS-S001 and improved kinematic parameters from new spectroscopic observations. From GMOS multi-object spectroscopy, we have been able to confirm a new set of 10 cluster members, resulting in a total 22 objects from previous observations. With these data, a dispersion velocity of σ= 887 ± 249 km s−1, a virial radius R200= 0.98 ± 0.22 Mpc and a mass of M200= (5.4 ± 2.8) × 1014 M⊙ have been derived. From GMOS i′ and r′ images, we have extracted the individual sources and derived their magnitudes, relative positions and the bulge+disc brightness profile decomposition. We show that the cluster has an elongated morphology along the north–south direction, with ellipticity ɛ= 0.49 ± 0.14, well represented by a King model with a core radius RC= 283 ± 66 kpc, above the typical core radii of regular clusters. It shows at least one local overdensity, north-west from the cluster centre, very compact and with a very high central density. The i′ luminosity function of LCDCS-S001 has an almost flat faint-end, α=−1.16 ± 0.18. As for the constituent galaxies, we have found that a large fraction of the cluster galaxies are late-type systems. Extensive simulations were made in order to verify the validity of our conclusions. We discuss the implication of these results for the evolutionary status of LCDCS-S001 and conclude that this cluster is still dynamically young.