Implications for galaxy formation models from observations of globular clusters around ultradiffuse galaxies

Teymoor Saifollahi, Dennis Zaritsky, Ignacio Trujillo, Reynier F. Peletier, Johan H. Knapen, Nicola Amorisco, Michael A. Beasley, Richard Donnerstein

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


We present an analysis of Hubble Space Telescope observations of globular clusters (GCs) in six ultradiffuse galaxies (UDGs) in the Coma cluster, a sample that represents UDGs with large effective radii (Re), and use the results to evaluate competing formation models. We eliminate two significant sources of systematic uncertainty in the determination of the number of GCs, NGC by using sufficiently deep observations that (i) reach the turnover of the globular cluster luminosity function (GCLF) and (ii) provide a sufficient number of GCs with which to measure the GC number radial distribution. We find that NGC for these galaxies is on average 20, which implies an average total mass, Mtotal, 1011 M when applying the relation between NGC and Mtotal. This value of NGC lies at the upper end of the range observed for dwarf galaxies of the same stellar mass and is roughly a factor of two larger than the mean. The GCLF, radial profile, and average colour are more consistent with those observed for dwarf galaxies than with those observed for the more massive (L∗) galaxies, while both the radial and azimuthal GC distributions closely follow those of the stars in the host galaxy. Finally, we discuss why our observations, specifically the GC number and GC distribution around these six UDGs, pose challenges for several of the currently favoured UDG formation models.

Original languageEnglish (US)
Pages (from-to)4633-4659
Number of pages27
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Apr 1 2022


  • dark matter
  • galaxies: clusters: individual: Coma
  • galaxies: evolution
  • galaxies: structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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