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Article
Extensive Globular Cluster Systems Associated with Ultra Diffuse Galaxies in the Coma Cluster
The Astrophysical Journal Letters (2017)
  • Pieter van Dokkum, Yale University
  • Roberto Abraham, University of Toronto
  • Aaron J. Romanowsky, San Jose State University
  • Jean P. Brodie, University of California Observatories
  • Charlie Conroy, Harvard-Smithsonian Center for Astrophysics
  • Shany Danieli, Yale University
  • Deborah Lokhors, University of Toronto
  • Allison Merritt, Yale University
  • Lamiya Mowla, Yale University
  • Jielai Zhang, University of Toronto
Abstract
We present Hubble Space Telescope (HST) imaging of two ultra diffuse galaxies (UDGs) with measured stellar velocity dispersions in the Coma cluster. The galaxies, Dragonfly 44 and DFX1, have effective radii of 4.7 kpc and 3.5 kpc and velocity dispersions of  km s−1 and  km s−1, respectively. Both galaxies are associated with a striking number of compact objects, tentatively identified as globular clusters:  for Dragonfly 44 and  for DFX1. The number of globular clusters is much higher than expected from the luminosities of the galaxies but is consistent with expectations from the empirical relation between dynamical mass and globular cluster count defined by other galaxies. Combining our data with previous HST observations of Coma UDGs we find that UDGs have a factor of  more globular clusters than other galaxies of the same luminosity, in contrast to a recent study of a similar sample by Amorisco et al., but consistent with earlier results for individual galaxies. The Harris et al. relation between globular cluster count and dark matter halo mass implies a median halo mass of   for the sixteen Coma UDGs that have been observed with HST so far, with the largest and brightest having  .
Keywords
  • galaxies: clusters: individual (Coma),
  • galaxies: evolution,
  • galaxies: structure
Publication Date
2017
DOI
10.3847/2041-8213/aa7ca2
Publisher Statement
This article was originally published in The Astrophysical Journal Letters, volume 844, issue 1. © 2017. The American Astronomical Society. All rights reserved.

This article is also available online at the following link: https://doi.org/10.3847/2041-8213/aa7ca2
Citation Information
Pieter van Dokkum, Roberto Abraham, Aaron J. Romanowsky, Jean P. Brodie, et al.. "Extensive Globular Cluster Systems Associated with Ultra Diffuse Galaxies in the Coma Cluster" The Astrophysical Journal Letters Vol. 844 Iss. 1 (2017) ISSN: 2041-8205
Available at: http://works.bepress.com/aaron_romanowsky/129/