Evidence for the First Globular Cluster Stellar Stream beyond the Milky Way
Abstract
The dark matter content of ultra-diffuse galaxies is the subject of considerable debate. Stellar streams, which form when a host galaxy tidally strips stars from an orbiting stellar system, provide a powerful technique to constrain the dark matter content of external galaxies. The stripped stars form long, thin leading and trailing tidal arms that persist for billions of years. Stellar streams from globular clusters are particularly sensitive probes of dark matter halos and substructure. Globular cluster streams are expected to exist in a variety of host galaxy types, but so far, they have only been observed in the Milky Way. We present evidence for the first extragalactic globular cluster stellar stream, identified in deep Hubble Space Telescope imaging of the ultra-diffuse galaxy, UGC9050-Dw1. The stream's morphology, colour, and apparent association with a compact source support the globular cluster progenitor interpretation observationally, and we reproduce the observed surface brightness with simulated globular cluster stellar populations. We use generative stream modelling, which fits dynamical models directly to the stream morphology, to constrain the mass of the progenitor and present the first stream-based halo constraint for an ultra-diffuse galaxy. The stream models point to a globular cluster origin and suggest a massive dark matter host halo. By extending the reach of globular cluster stream analysis to external galaxies, this work opens a new chapter in dark matter science.
Versions
Related
- Ballistic mixing: Stellar mergers drive internal mixing in extremely massive stars with implications for proto-globular cluster pollution
- Modeling Globular Cluster Stellar Streams with a Basis-expansion N -body Code
- Ballistic mixing: stellar mergers drive internal mixing in extremely massive stars, with implications for proto-globular cluster pollution
- Globular cluster formation with multiple stellar populations: A comprehensive overview of a star-cloud interaction scenario
- Evidence for the Typhon Stellar Stream as the Remnant of a Recently-disrupted Dwarf Galaxy
BibTeX
@misc{holm2026evidence,
title = {{Evidence for the First Globular Cluster Stellar Stream beyond the Milky Way}},
author = {Julie Kiel Holm and Sarah Pearson and Jacob Nibauer and David J. Sand and Adrian M. Price-Whelan and Tjitske Starkenburg and David Hendel and Catherine Fielder},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.12254},
eprint = {2608.12254},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.12254},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Evidence for the First Globular Cluster Stellar Stream beyond the Milky Way
AU - Julie Kiel Holm
AU - Sarah Pearson
AU - Jacob Nibauer
AU - David J. Sand
AU - Adrian M. Price-Whelan
AU - Tjitske Starkenburg
AU - David Hendel
AU - Catherine Fielder
PY - 2026
DA - 2026/08/12
PB - arXiv
DO - 10.48550/arxiv.2608.12254
UR - https://arxiv.org/abs/2608.12254
AB - The dark matter content of ultra-diffuse galaxies is the subject of considerable debate. Stellar streams, which form when a host galaxy tidally strips stars from an orbiting stellar system, provide a powerful technique to constrain the dark matter content of external galaxies. The stripped stars form long, thin leading and trailing tidal arms that persist for billions of years. Stellar streams from globular clusters are particularly sensitive probes of dark matter halos and substructure. Globular cluster streams are expected to exist in a variety of host galaxy types, but so far, they have only been observed in the Milky Way. We present evidence for the first extragalactic globular cluster stellar stream, identified in deep Hubble Space Telescope imaging of the ultra-diffuse galaxy, UGC9050-Dw1. The stream's morphology, colour, and apparent association with a compact source support the globular cluster progenitor interpretation observationally, and we reproduce the observed surface brightness with simulated globular cluster stellar populations. We use generative stream modelling, which fits dynamical models directly to the stream morphology, to constrain the mass of the progenitor and present the first stream-based halo constraint for an ultra-diffuse galaxy. The stream models point to a globular cluster origin and suggest a massive dark matter host halo. By extending the reach of globular cluster stream analysis to external galaxies, this work opens a new chapter in dark matter science.
ER -