Luminosity functions in the CLASH-VLT cluster MACS J1206.2-0847: the importance of tidal interactions

TL;DR

This study analyzes the luminosity functions of galaxies in the MACS J1206.2-0847 cluster, revealing a bimodal distribution influenced by tidal interactions and environmental factors, with implications for galaxy evolution and intra-cluster light.

Contribution

It provides detailed luminosity functions across different regions of the cluster, highlighting the impact of tidal interactions on faint galaxies and the importance of environment.

Findings

Faint-end upturn in luminosity function suggests bimodal galaxy distribution.

Fainter galaxies are more affected by tidal interactions, especially in outer regions.

Environmental dependence of the luminosity function slope supports tidal interaction effects.

Abstract

We present the optical luminosity functions (LFs) of galaxies for the CLASH-VLT cluster MACS J1206.2-0847 at z=0.439, based on HST and SUBARU data, including ~600 spectroscopically confirmed member galaxies. The LFs on the wide SUBARU FoV are well described by a single Schechter function down to M~M*+3, whereas this fit is poor for HST data, due to a faint-end upturn visible down M~M*+7, suggesting a bimodal behaviour. We also investigate the effect of local environment by deriving the LFs in four different regions, according to the distance from the centre, finding an increase in the faint-end slope going from the core to the outer rings. Our results confirm and extend our previous findings on the analysis of mass functions, which showed that the galaxies with stellar mass below 10^10.5, M_sun have been significantly affected by tidal interaction effects, thus contributing to the intra cluster light.