The Stellar Populations of Two Quiescent Low Surface Brightness Dwarf Galaxies in Low Density Environments
Abstract
Dwarf galaxies located in low density environments that have quiescent stellar populations are extremely rare and the mechanism for quenching their stars is highly uncertain. Here we present two low surface brightness dwarf galaxies with large (>1.2 kpc) effective radii that were previously identified in the Dragonfly Ultrawide Survey for which we have obtained spectra using the KCWI instrument on the Keck II telescope. We derive their stellar populations and star formation histories in several radial bins out to 1.25 effective radii. Globally both galaxies are old (~9 Gyr) and metal-poor ([M/H] ~ -1) and reveal quenching on a relatively rapid timescale (~1 Gyr). We find flat to rising age and metallicity gradients in both galaxies. This is similar to those seen in ultra diffuse galaxies but is in contrast with typical classical dwarf galaxies and predictions from simulations. One galaxy, DFUWS 68, hosts several globular clusters which we find to share similar ages, metallicities and quenching timescales to that of the host galaxy stars.We briefly discuss possible quenching mechanisms and suggest that neither cosmic web stripping nor internal feedback processes alone can explain our results.
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BibTeX
@misc{forbes2026stellar,
title = {{The Stellar Populations of Two Quiescent Low Surface Brightness Dwarf Galaxies in Low Density Environments}},
author = {Duncan A. Forbes and Hannah S. Christie and Arsen Levitskiy and Jonah S. Gannon and Anna Ferre-Mateu Aaron J. Romanowsky and Jean P. Brodie},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.00693},
eprint = {2609.00693},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.00693},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Stellar Populations of Two Quiescent Low Surface Brightness Dwarf Galaxies in Low Density Environments
AU - Duncan A. Forbes
AU - Hannah S. Christie
AU - Arsen Levitskiy
AU - Jonah S. Gannon
AU - Anna Ferre-Mateu Aaron J. Romanowsky
AU - Jean P. Brodie
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.00693
UR - https://arxiv.org/abs/2609.00693
AB - Dwarf galaxies located in low density environments that have quiescent stellar populations are extremely rare and the mechanism for quenching their stars is highly uncertain. Here we present two low surface brightness dwarf galaxies with large (>1.2 kpc) effective radii that were previously identified in the Dragonfly Ultrawide Survey for which we have obtained spectra using the KCWI instrument on the Keck II telescope. We derive their stellar populations and star formation histories in several radial bins out to 1.25 effective radii. Globally both galaxies are old (~9 Gyr) and metal-poor ([M/H] ~ -1) and reveal quenching on a relatively rapid timescale (~1 Gyr). We find flat to rising age and metallicity gradients in both galaxies. This is similar to those seen in ultra diffuse galaxies but is in contrast with typical classical dwarf galaxies and predictions from simulations. One galaxy, DFUWS 68, hosts several globular clusters which we find to share similar ages, metallicities and quenching timescales to that of the host galaxy stars.We briefly discuss possible quenching mechanisms and suggest that neither cosmic web stripping nor internal feedback processes alone can explain our results.
ER -