A Detailed Study of Dwarf Galaxies in the Core of the Coma Cluster

TL;DR

This study classifies and analyzes the structural and photometric properties of dwarf galaxies in the Coma Cluster core, revealing their distinct formation and evolution processes compared to larger galaxies.

Contribution

It provides a detailed morphological and structural analysis of dwarf galaxies in the Coma Cluster, including classifications and property correlations, which was not comprehensively done before.

Findings

Dwarf ellipticals are redder and fainter than other dwarfs.

Dwarf ellipticals have lower surface brightness.

Structural fits vary among dwarf galaxy types.

Abstract

In an earlier paper, we determined the morphological types of galaxies in the Coma Cluster using data from the HST/ACS Coma Cluster treasury survey. We found that of the 132 members, 51 are non dwarfs and 81 are dwarfs. We define dwarfs to have a absolute luminosity $M_{F814W}\geq -18.5$ as in \cite{2012ApJ...746..136M}. In this paper, we determine the morphological types of these dwarf galaxies and make a detailed study of their properties. Using GALFIT, we determine the structural properties of our sample and with spectroscopic redshifts, we determined memberships and distances to identify dwarfs. A visual examination of the residual images reveals that our sample of 78 dwarf galaxies comprises of: dwarf lenticular (\textit{dS0}) 22\%, dwarf Elliptical ($dE$) 69\%, dwarf spirals (\textit{dSp}) 4\%, dwarf ring (\textit{dring}) 1\%, dwarf barred spirals (\textit{dSBp}) 3\% and dwarf irregular (\textit{dIrr}) 1\% galaxies. We find that the bulge-disk decomposition (S\'ersic + exponential) fits are good only for the \textit{dS0} galaxies. The remainder of the sample gives good fits only for single S\'ersic fits. The Colour Magnitude Relation (CMR) shows that the $dEs$ are redder and fainter than the rest of the sample (except one $dIrr$ galaxy). The Kormendy relation reveals that $dE$ galaxies have lower surface brightness than the rest of the sample. Our research leads us to the conclusion that dwarf galaxies appear to have a different formation and evolution process than non-dwarf galaxies.