Keck/LRIS Spectroscopic Confirmation of Coma Cluster Dwarf Galaxy Membership Assignments

Abstract

Keck/LRIS multi-object spectroscopy has been carried out on 140 of some of the lowest and highest surface brightness faint (19 < R < 22) dwarf galaxy candidates in the core region of the Coma Cluster. These spectra are used to measure redshifts and establish membership for these faint dwarf populations. The primary goal of the low surface brightness sample is to test our ability to use morphological and surface brightness criteria to distinguish between Coma Cluster members and background galaxies using high resolution HST/ACS images. Candidates were rated as expected members, uncertain, or expected background. From 93 spectra, 51 dwarf galaxy members and 20 background galaxies are identified. Our morphological membership estimation success rate is ~100% for objects expected to be members and better than ~90% for galaxies expected to be in the background. We confirm that low surface brightness is a very good indicator of cluster membership. High surface brightness galaxies are almost always background with confusion arising only from the cases of the rare compact elliptical galaxies. The more problematic cases occur at intermediate surface brightness. Many of these galaxies are given uncertain membership ratings, and these were found to be members about half of the time. Including color information will improve membership determination but will fail for some of the same objects that are already mis-identified when using only surface brightness and morphology criteria. Compact elliptical galaxies with B-V colors ~0.2 magnitudes redward of the red sequence in particular require spectroscopic follow-up. In a sample of 47 high surface brightness, UCD candidates, 19 objects have redshifts which place them in the Coma Cluster. Redshift measurements are presented and the use of indirect means for establishing cluster membership is discussed.

Accepted for publication in ApJ, 25 pages, 15 figures

References in corpus (12)

• The Nature of UCDs: Internal Dynamics from an Expanded Sample and Homogeneous Database
• Strange filamentary structures ("fireballs") around a merger galaxy in the Coma cluster of galaxies
• The HST/ACS Coma Cluster Survey: I - Survey Objectives and Design
• The origin of the mu_e - M_B and Kormendy relations in dwarf elliptical galaxies
• A search for ultra-compact dwarf galaxies in the Centaurus galaxy cluster
• On the Dynamical Origin of the ICM Metallicity Evolution
• Deep and wide field imaging of the Coma cluster: the data
• Stellar Population Constraints on the Dark Matter Content and Origin of Ultra-Compact Dwarf Galaxies
• UCD Candidates in the Hydra Cluster
• Compact stellar systems and cluster environments
• Morphology of galaxies in the Coma cluster region down to M_B=-14.25. I. A catalog of 473 members
• Ultra-Compact Dwarf Candidates Near the Lensing Galaxy in Abell S0740

Cited by in corpus (20)

• The HST/ACS Coma Cluster Survey. X. Nuclear star clusters in low-mass early-type galaxies: scaling relations
• Galaxy Groups
• The HST/ACS Coma Cluster Survey III. Structural Parameters of Galaxies using single-Sérsic Fits
• Dwarf galaxy populations in present-day galaxy clusters: I. Abundances and red fractions
• The specific frequencies of ultra-compact dwarf galaxies
• Ultra-Compact Dwarfs in the Coma Cluster
• Constraining ultra-compact dwarf galaxy formation with galaxy clusters in the local universe
• The HST/ACS Coma Cluster Survey: VII - Colour Gradients in Giant and Dwarf Early-Type Galaxies
• H I content in Coma cluster substructure
• The HST/ACS Coma Cluster Survey - VII. Structure and Assembly of Massive Galaxies in the Center of the Coma Cluster
• Galaxy populations in the Antlia cluster - III. Properties of faint early-type galaxies
• The Galaxy Luminosity Functions down to M_R=-10 in the Coma Cluster
• Giant Galaxies, Dwarfs, and Debris Survey. I. Dwarf Galaxies and Tidal Features Around NGC 7331
• An expanded catalogue of low surface brightness galaxies in the Coma cluster using Subaru/Suprime-Cam
• Ultra-Compact Dwarfs in the Fossil Group NGC 1132
• The evolution of dwarf galaxies in the Coma supercluster
• Galaxy Luminosity Function of Dynamically Young Abell 119 Cluster: Probing the Cluster Assembly
• About the linearity of the color-magnitude relation of early-type galaxies in the Virgo cluster
• Deep UV Luminosity Functions at the Infall Region of the Coma Cluster
• Statistical analysis of bound companions in the Coma cluster