Publication Date

1-1-2020

Document Type

Article

Publication Title

Monthly Notices of the Royal Astronomical Society

Volume

492

Issue

4

DOI

10.1093/MNRAS/STAA180

First Page

487

Last Page

4883

Abstract

Ultra-diffuse galaxies (UDGs) reveal extreme properties. Here, we compile the largest study to date of 85 globular cluster (GC) systems around UDGs in the Coma cluster, using new deep ground-based imaging of the known UDGs and existing imaging from the Hubble Space Telescope of their GC systems. We find that the richness of GC systems in UDGs generally exceeds that found in normal dwarf galaxies of the same stellar mass. These GC-rich UDGs imply haloes more massive than expected from the standard stellar mass–halo mass relation. The presence of such overly massive haloes presents a significant challenge to the latest simulations of UDGs in cluster environments. In some exceptional cases, the mass in the GC system is a significant fraction of the stellar content of the host galaxy. We find that rich GC systems tend to be hosted in UDGs of lower luminosity, smaller size, and fainter surface brightness. Similar trends are seen for normal dwarf galaxies in the Coma cluster. A toy model is presented in which the GC-rich UDGs are assumed to be ‘failed’ galaxies within massive haloes that have largely old, metal-poor, alpha-element-enhanced stellar populations. On the other hand, GC-poor UDGs are more akin to normal, low surface brightness dwarfs that occupy less massive dark matter haloes. Additional data on the stellar populations of UDGs with GC systems will help to further refine and test this simplistic model.

Funding Number

AST-1518294

Funding Sponsor

Research Corporation for Science Advancement

Keywords

Galaxies: evolution, Galaxies: haloes, Galaxies: star clusters

Comments

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Department

Physics and Astronomy

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