Publication Date
11-1-2022
Document Type
Article
Publication Title
Monthly Notices of the Royal Astronomical Society
Volume
517
Issue
1
DOI
10.1093/mnras/stac2717
First Page
858
Last Page
871
Abstract
We investigate the isolated, quiescent ultra-diffuse galaxy (UDG) DGSAT I and its globular cluster (GC) system using two orbits of Hubble Space Telescope Advanced Camera for Surveys imaging in the F606W and F814W filters. This is the first study of GCs around a UDG in a low-density environment. DGSAT I was previously found to host an irregular blue low surface brightness clump, which we confirm as very likely belonging to the galaxy rather than being a chance projection, and represents a recent episode of star formation (∼500 Myr) that challenges some UDG formation scenarios. We select GC candidates based on colours and magnitudes, and construct a self-consistent model of the GC radial surface density profile along with the background. We find a half-number radius of RGC = 2.7 ± 0.1 kpc (more compact than the diffuse starlight) and a total of 12 ± 2 GCs. The total mass fraction in GCs is relatively high, supporting an overmassive dark matter halo as also implied by the high velocity dispersion previously measured. The GCs extend to higher luminosities than expected, and have colours that are unusually similar to their host galaxy colour, with a very narrow spread, all of which suggest an early, intense burst of cluster formation. The nature and origin of this galaxy remain puzzling, but the most likely scenario is a ‘failed galaxy’ that formed relatively few stars for its halo mass, and could be related to cluster UDGs whose size and quiescence pre-date their infall.
Funding Number
HST-GO-14846
Funding Sponsor
National Aeronautics and Space Administration
Keywords
galaxies: dwarf, galaxies: formation, galaxies: star clusters: general
Department
Physics and Astronomy
Recommended Citation
Steven R. Janssens, Aaron J. Romanowsky, Roberto Abraham, Jean P. Brodie, Warrick J. Couch, Duncan A. Forbes, Seppo Laine, David Martínez-Delgado, and Pieter G. van Dokkum. "The globular clusters and star formation history of the isolated, quiescent ultra-diffuse galaxy DGSAT I" Monthly Notices of the Royal Astronomical Society (2022): 858-871. https://doi.org/10.1093/mnras/stac2717
Comments
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2022 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.