On the nature of faint Low Surface Brightness galaxies in the Coma cluster

TL;DR

This study investigates faint Low Surface Brightness Galaxies in the Coma cluster, analyzing their spectral energy distributions to understand their properties, origins, and cluster membership, revealing diverse ages, dust content, and possible disruptive origins.

Contribution

It provides a detailed spectral analysis of fLSBs in the Coma cluster, identifying their ages, dust extinctions, and cluster membership criteria using broad band photometry and population synthesis models.

Findings

Approximately 80% of well-represented fLSBs are likely cluster members.

Most fLSBs are young, non-starburst, and some are quite dusty.

fLSBs are low-mass objects with properties linked to infall directions.

Abstract

This project is the continuation of our study of faint Low Surface Brightness Galaxies (fLSBs) in one of the densest nearby galaxy regions known, the Coma cluster. Our goal is to improve our understanding of the nature of these objects by comparing the broad band spectral energy distribution with population synthesis models. The data were obtained with the MEGACAM and CFH12K cameras at the CFHT. We used the resulting photometry in 5 broad band filters (u*, B, V, R, and I), that included new u*-band data, to fit spectral models. With these spectral fits we inferred a cluster membership criterium, as well as the ages, dust extinctions, and photometric types of these fLSBs. We show that about half of the Coma cluster fLSBs have a spectral energy distribution well represented in our template library while the other half present a flux deficit at ultraviolet wavelengths. Among the well represented, ~80% are probably part of the Coma cluster based on their spectral energy distribution. They are relatively young (younger than 2.3 Gyrs for 90% of the sample) non-starburst objects. The later their type, the younger fLSBs are. A significant part of the fLSBs are quite dusty objects. fLSBs are low stellar mass objects (the later their type the less massive they are), with stellar masses comparable to globular clusters for the faintest ones. Their characteristics are correlated with infall directions, confirming the disruptive origin for part of them.