The cluster galaxy luminosity function at $z=0.3$: a recent origin for the faint-end upturn ?

TL;DR

This study investigates the evolution of the faint-end upturn in galaxy luminosity functions, finding it absent at higher redshifts and suggesting it forms recently through infall or tidal disruption.

Contribution

It provides evidence that the faint-end upturn in galaxy luminosity functions develops at low redshift, indicating recent formation processes in galaxy clusters.

Findings

Faint-end upturn absent at z=0.3, present in local clusters.

Faint-end upturn likely formed recently, not at earlier cosmic times.

Supports models of recent galaxy infall or tidal disruption as origins.

Abstract

We derive deep luminosity functions (to $M_z=-15$) for galaxies in Abell 1835 ($z=0.25$) and AC 114 ($z=0.31$) and compare these with the local $z'$ luminosity function for 69 clusters. The data show that the faint-end upturn, the excess of galaxies above a single Schechter function at $M_z < -17$, does not exist in the higher redshift clusters. This suggests that the faint-end upturn galaxies have been created recently, by infall into clusters of star-forming field populations or via tidal disruption of brighter objects.^M