Signatures of quenching in dwarf galaxies in local galaxy clusters

TL;DR

This study investigates the transformation of dwarf galaxies in the Virgo and Fornax clusters, finding correlations between surface brightness and colour consistent with quenching and stellar population models, but with notable differences between galaxy types.

Contribution

It extends the analysis of surface brightness-colour relations to the Virgo cluster and compares results across two clusters, revealing insights into galaxy transformation processes.

Findings

Correlations between surface brightness and colour are similar in Virgo and Fornax clusters.

Surface brightness-colour relations are consistent with fading and reddening stellar population models.

Early- and late-type dwarf galaxies show different signatures of stellar population evolution.

Abstract

The transformation of late-type galaxies has been suggested as the origin of early-type dwarf galaxies in galaxy clusters. Venhola et al. analysed correlations between colour and surface brightness for galaxies in the Fornax cluster binned by luminosity or stellar mass. In the bins with $M_\star<10^8 {\rm M}_\odot$, the authors identified a correlation of redness with fainter surface brightness and interpreted it as a consequence of the quenching of star formation by ram pressure stripping in the dwarf galaxies. We carry out a corresponding analysis for the Virgo cluster and find great similarities in these correlations between surface brightness and colour for the two clusters, despite expected differences in the strength of the ram pressure. Furthermore, we extend the analysis to a wider range of optical colours for both clusters and contrast the results with expectations for fading and reddening stellar populations. Overall the slopes of the surface brightness-colour relations are consistent with these models. In addition the sizes of the early- and late-type galaxies at these low masses are comparable. These two results are compatible with a transformation scenario. However, when analysing early- and late-type galaxies separately, the consistency of the slope of the surface brightness-colour relations with the model expectations for fading and reddening stellar population applies only to the late types. The lack of this imprint for the early-type dwarfs calls for some additional explanation, for which we discuss several possibilities. Finally, the Virgo cluster is an atypical cluster with a low fraction of quiescent early-type galaxies at all galaxy masses despite its large cluster mass. (abridged)