The Sausage Globular Clusters
Open accessAbstract
The Gaia Sausage is an elongated structure in velocity space discovered by Belokurov et al. using the kinematics of metal-rich halo stars. They showed that it could be created by a massive dwarf galaxy (∼5 × 10 10 ) on a strongly radial orbit that merged with the Milky Way at a redshift z ≲ 3. This merger would also have brought in globular clusters (GCs). We seek evidence for the associated Sausage Globular Clusters (GCs) by analyzing the structure of 91 Milky Way GCs in action space using the Gaia Data Release 2 catalog, complemented with Hubble Space Telescope proper motions. There is a characteristic energy that separates the in situ objects, such as the bulge/disk clusters, from the accreted objects, such as the young halo clusters. There are 15 old halo GCs that have E > . Eight of the high-energy, old halo GCs are strongly clumped in azimuthal and vertical action, yet strung out like beads on a chain at extreme radial action. They are very radially anisotropic ( β ∼ 0.95) and move on orbits that are all highly eccentric ( e ≳ 0.80). They also form a track in the age–metallicity plane compatible with a dwarf galaxy origin. These properties are consistent with GCs associated with the merger event that gave rise to the Gaia Sausage.
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References 17 · Cited by 213
Research works printed but not linked: 9
- Belokurov, V., Erkal, D., Evans, N. W., Koposov, S. E., & Deason, A. J. 2018b, arXiv:1802.03414 · arXiv
- Binney, J., & Tremaine, S. 2008, Galactic Dynamics (2nd ed.; Princeton Univ. Press: Princeton, NJ)
- Goldstein, H. 1980, Classical Mechanics (Reading, MA: Addison-Wesley)
- Haywood, M., Di Matteo, P., Lehnert, M., et al. 2018, arXiv:1805.02617 · arXiv
- Gaia Collaboration, Helmi, A., van Leeuwen, F., et al. 2018, arXiv:1804.09381 · arXiv
- Myeong, G. C., Evans, N. W., Belokurov, V., Sanders, J. L., & Koposov, S. E. 2018b, arXiv:1804.07050 · arXiv
- Posti, L., & Helmi, A. 2018, arXiv:1805.01408 · arXiv
- Sohn, S. T., Watkins, L. L., Fardal, M. A., et al. 2018, arXiv:1804.01994 · arXiv
- Zinn, R. 1993, in ASP Conf. Ser. 38, The Globular Cluster-Galaxy Connection, ed. G. H. Smith & J. P. Brodie (San Francisco, CA: ASP), 38 Figure 5. Upper panel: plot of the age of GCs vs. metallicity using data from Forbes & Bridges (2010). The Sausage GCs are shown with circular (probables) and square (possibles) black boundaries. Seven GCs that are claimed as former denizens of Sgr are shown as unfilled black diamonds. The sequences of Sgr GCs and Sausage GCs lie on two distinct, though closely matched, tracks. They are different from the bulk of the Milky Way GCs, which show a constant age of ∼13 Gyr independent of metallicity. Lower panel: plot of horizontal branch morphology vs. metallicity using data from
- Authors
- Myeong, G. C., Evans, N. W., Belokurov, V., Sanders, J. L., & Koposov, S. E.
- Affiliations
- University of Cambridge (GB)
- Venue
- The Astrophysical Journal Letters
- Publisher
- American Astronomical Society
- Published
- 2018-08-17
- Volume
- 863
- Issue
- 2
- Pages
- L28
- ISSN
- 2041-8205 (ISSN-L)
- 2041-8213
- OpenAlex
- W2798363098
- Cited by
- 213
- References
- 17
- Citations by year
- 2026: 14 · 2025: 19 · 2024: 15 · 2023: 22 · 2022: 21 · 2021: 35 · 2020: 40 · 2019: 38 · 2018: 9
- FWCI
- 15.99
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- The Astrophysical Journal Letters (publishedVersion)
- arXiv (Cornell University) (submittedVersion)
- Edinburgh Research Explorer (University of Edinburgh) (submittedVersion, other-oa)
- arXiv (Cornell University)
- Funders
- Science and Technology Facilities Council (ST/N000927/1)
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Stellar, planetary, and galactic studies
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
- Physical Sciences › Physics and Astronomy › Instrumentation › Astronomy and Astrophysical Research
- Keywords
- globular clusters, Milky Way accretion history, dwarf galaxy mergers, eccentric orbits, age-metallicity relation, cluster kinematics, Gaia DR2
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