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The globular clusters and star formation history of the isolated, quiescent ultra-diffuse galaxy DGSAT I

Janssens, Steven R. and Romanowsky, Aaron J. and Abraham, Roberto G. and Brodie, Jean P. and Couch, Warrick J. and Forbes, Duncan A. and Laine, Seppo and Martínez-Delgado, David and van Dokkum, Pieter G. (2022) The globular clusters and star formation history of the isolated, quiescent ultra-diffuse galaxy DGSAT I. Monthly Notices of the Royal Astronomical Society, 517 (1). pp. 858-871. ISSN 0035-8711. doi:10.1093/mnras/stac2717.

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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 R_(GC) = 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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Janssens, Steven R.0000-0003-0327-3322
Romanowsky, Aaron J.0000-0003-2473-0369
Abraham, Roberto G.0000-0002-4542-921X
Brodie, Jean P.0000-0002-9658-8763
Couch, Warrick J.0000-0001-5005-3125
Forbes, Duncan A.0000-0001-5590-5518
Laine, Seppo0000-0003-1250-8314
Martínez-Delgado, David0000-0003-3835-2231
van Dokkum, Pieter G.0000-0002-8282-9888
Additional Information:We thank the anonymous referee for suggestions which improved the quality of the manuscript, and Shany Danieli, Bill Harris, and Viraj Pandya for helpful discussions. We thank NSERC for financial support. SRJ acknowledges funding support from the Australian Research Council through Discovery Project grant DP200102574 during the course of this work. AJR was supported as a Research Corporation for Science Advancement Cottrell Scholar. DMD acknowledges financial support from the Talentia Senior Program (through the incentive ASE-136) from Secretaría General de Universidades, Investigación y Tecnología, de la Junta de Andalucía. DMD acknowledges funding from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709) and project (PDI2020-114581GB-C21/ AEI / 10.13039/501100011033). Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Support for Program number HST-GO-14846 was provided through a grant from the STScI under NASA contract NAS5-26555. This research has used the NASA/IPAC Infrared Science Archive, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This research used ASTROPY,11 a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018). This research used PHOTUTILS, an Astropy package for detection and photometry of astronomical sources (Bradley et al. 2021). This research has used the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has used NASA’s Astrophysics Data System Bibliographic Services.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Australian Research CouncilDP200102574
Ministerio de Ciencia, Innovación y Universidades (MCIU)UNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20221024-125854800.22
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117552
Deposited By: Research Services Depository
Deposited On:01 Nov 2022 21:04
Last Modified:01 Nov 2022 21:04

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