The number of globular clusters around the iconic UDG DF44 is as expected for dwarf galaxies

Teymoor Saifollahi*, Ignacio Trujillo*, Michael A. Beasley, Reynier F. Peletier, Johan H. Knapen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

35 Citations (Scopus)
54 Downloads (Pure)

Abstract

There is a growing consensus that the vast majority of ultradiffuse galaxies (UDGs) are dwarf galaxies. However, there remain a few UDGs that seem to be special in terms of their globular cluster (GC) systems. In particular, according to some authors, certain UDGs exhibit large GC populations when compared to expectations from their stellar (or total) mass. Among these special UDGs, DF44 in the Coma cluster is one of the better-known examples. DF44 has been claimed to have a relatively high number of GCs, $N_{\mathrm{ GC}}=74^{+18}_{-18}$, for a stellar mass of only $3\times 10^8\, \mathrm{ M}_{ \odot}$ which would indicate a much larger dark halo mass than dwarfs of similar stellar mass. In this paper, we revisit this number and, contrary to previous results, find $N_{\mathrm{ GC}}=21^{+7}_{-9}$ assuming that the distribution of the GCs follows the same geometry as the galaxy. If we assume that the GCs around DF44 are distributed in a (projected) circularly symmetric way and, if we use a less strict criterion for the selection of the GCs, we find $N_{\mathrm{ GC}}=18^{+23}_{-12}$. Making use of the MGC-Mhalo relation, this number of GCs suggests a dark matter halo mass of $M_{\mathrm{ halo}}=1.1^{+0.4}_{-0.5} \times 10^{11} \mathrm{ M}_{\odot}$, a value which is consistent with the expected total mass for DF44 based on its velocity dispersion, $\sigma =33^{+3}_{-3}$ km s-1. We conclude that the number of GCs around DF44 is as expected for regular dwarf galaxies of similar stellar mass and DF44 is not extraordinary in this respect.

Original languageEnglish
Pages (from-to)5921-5934
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume502
Issue number4
DOIs
Publication statusPublished - Apr-2021

Keywords

  • dark matter
  • galaxies: clusters: individual (Coma)
  • galaxies: evolution
  • galaxies: individual (DF44) (Coma)
  • galaxies: structure

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