A search for faint low surface brightness galaxies in the relaxed cluster Abell 496

TL;DR

This study searches for faint low surface brightness galaxies in the relaxed cluster Abell 496 using deep imaging, compares their properties with those in the Coma cluster, and explores environmental effects on their formation.

Contribution

It provides the first detailed analysis of fLSBs in Abell 496, comparing their properties with those in a more disturbed cluster to understand environmental influences.

Findings

Many fLSBs follow the red sequence of brighter galaxies.

Red fLSBs are homogeneously distributed, while others are aligned with large-scale filaments.

Red fLSBs likely formed in groups before cluster assembly.

Abstract

Cluster faint low surface brightness galaxies (fLSBs) are difficult to observe. Consequently, their origin, physical properties and number density are not well known. After a first search for fLSBs in the highly substructured Coma cluster, we present here a search for fLSBs in Abell 496. This cluster appears to be much more relaxed than Coma, but is embedded in a large scale filament of galaxies. Our aim is to compare the properties of fLSBs in these two very different clusters, to search for environmental effects. Based on deep CFHT/Megacam images in the u*, g', r' and i' bands, we selected galaxies with r'>21 and surface brightness > 24 mag/arcsec-2. We estimated photometric redshifts for all these galaxies and kept the 142 fLSBs with photo-z<0.2. In a g'-i' versus i' color-magnitude diagram, we find that a large part of these fLSBs follow the red sequence (RS) of brighter galaxies. The fLSBs within +-1sigma of the RS show a homogeneous spatial distribution, while those above the RS appear to be concentrated along the large scale filament of galaxies. These properties are interpreted as agreeing with the idea that RS fLSBs are formed in groups prior to cluster assembly. The formation of red fLSBs could be related to infalling galaxies.