Breaking Down the CosmoGEMS: Toward Modeling and Understanding Globular Cluster Stellar Streams in a Fully Cosmological Context
Creators
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1.
Carnegie Observatories
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2.
California Institute of Technology
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3.
University of Pennsylvania
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4.
University of North Carolina at Chapel Hill
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Northwestern University
- 6. NSF-Simons AI Institute for the Sky (SkAI), 172 E. Chestnut Street, Chicago, IL 60611, USA
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7.
University of Copenhagen
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8.
University of Washington
Abstract
Next-generation surveys are expected to uncover thousands of globular cluster (GC) stellar streams, motivating the need for a theoretical framework that produces realistic GC streams in a fully cosmological, Milky Way–like environment. We present CosmoGEMS , a star-by-star cosmological GC stream framework that self-consistently links small-scale cluster physics with large-scale Galactic dynamics. The initial phase-space positions of stream stars are informed by post-processed GC populations within the FIRE cosmological simulation. Escaped stars are orbit-integrated from their time of escape to the present day in a time-evolving Galactic potential extracted from the same simulation using a basis function expansion. We explore two example streams on different orbits. One forms a long, thin stream with a velocity dispersion consistent with Milky Way GC streams. However, it exhibits a clump and orbital-phase-dependent misalignments due to the evolving potential. The other stream develops both a thin component and a diffuse, shell-like structure, similar to features observed in streams like Jhelum. These results highlight the power of fully cosmological models in producing realistic stream morphologies and kinematics. Unlike idealized simulations, our models naturally incorporate time-dependent changes in the progenitor's orbit, including orbital plane evolution, which significantly affects stream structure. This challenges common assumptions in stream-finding algorithms and interpretation. CosmoGEMS provides a key step toward connecting future stellar stream observations with the physics of GC evolution and hierarchical galaxy formation in a cosmological context.
Copyright and License
© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
This work was made possible by NASA grant 22-ROMAN22-0055, and supported by NASA grant 22-ROMAN22-0013. This work was supported by a research grant (VIL53081) from VILLUM FONDEN. Funded/Co-funded by the European Union (ERC, BeyondSTREAMS, 101115754). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. This work was supported by NSF Grant AST-2310362. N.P. is grateful for support from the Carnegie–Caltech Joint Postdoctoral Fellowship. C.L.R. acknowledges support from the Alfred P. Sloan Foundation and the David and Lucile Packard Foundation. B.T.C. was partially funded by the North Carolina Space Grant’s Graduate Research Fellowship. T.S. gratefully acknowledges the support of the NSF-Simons AI-Institute for the Sky (SkAI) via grants NSF AST-2421845 and Simons Foundation MPS-AI-00010513. P.F.H. was supported by a Simons Investigator Grant. This project was developed in part at the Streams24 meeting hosted at Durham University. We also thank Mike Grudić, Nora Shipp, and Peter Ferguson for helpful discussion and input.
Software References
Astropy (Astropy Collaboration et al. 2013, 2018, 2022), IPython (F. Perez & B. E. Granger 2007), Matplotlib (J. D. Hunter 2007), Numpy (C. R. Harris et al. 2020), Scipy (P. Virtanen et al. 2020), halo_analysis (A. Wetzel & S. Garrison-Kimmel 2020a), gizmo_analysis (A. Wetzel & S. Garrison-Kimmel 2020b), agama (E. Vasiliev 2019), CMC (C. L. Rodriguez et al. 2022), NASA’s Astrophysics Data System.
Files
Panithanpaisal_2026_ApJ_997_182.pdf
Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2509.03599 (arXiv)
Funding
- National Aeronautics and Space Administration
- 22-ROMAN22-0055
- National Aeronautics and Space Administration
- 22-ROMAN22-0013
- Villum Fonden
- VIL53081
- European Research Council
- 101115754
- National Science Foundation
- AST-2310362
- Alfred P. Sloan Foundation
- David and Lucile Packard Foundation
- North Carolina Space Grant Consortium
- National Science Foundation
- AST-2421845
- Simons Foundation
- MPS-AI-00010513
Dates
- Submitted
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2025-09-30
- Accepted
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2025-12-15
- Available
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2026-01-22Published
Caltech Custom Metadata
- Caltech groups
- Astronomy Department , TAPIR , Walter Burke Institute for Theoretical Physics , Division of Physics, Mathematics and Astronomy (PMA) , Physics Department
- Publication Status
- Published