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Globular clusters as probes of dark matter cusp-core transformations

Orkney, M D A, Read, J I, Petts, J A and Gieles, M (2019) Globular clusters as probes of dark matter cusp-core transformations Monthly Notices of the Royal Astronomical Society, 488 (3). pp. 2977-2988.

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Abstract

Bursty star formation in dwarf galaxies can slowly transform a steep dark matter cusp into a constant density core. We explore the possibility that globular clusters (GCs) retain a dynamical memory of this transformation. To test this, we use the NBODY6DF code to simulate the dynamical evolution of GCs, including stellar evolution, orbiting in static and time-varying potentials for a Hubble time. We find that GCs orbiting within a cored dark matter halo, or within a halo that has undergone a cusp-core transformation, grow to a size that is substantially larger (Reff ˃ 10 pc) than those in a static cusped dark matter halo. They also produce much less tidal debris. We find that the cleanest signal of an historic cusp-core transformation is the presence of large GCs with tidal debris. However, the effect is small and will be challenging to observe in real galaxies. Finally, we qualitatively compare our simulated GCs with the observed GC populations in the Fornax, NGC 6822, IKN, and Sagittarius dwarf galaxies. We find that the GCs in these dwarf galaxies are systematically larger (〈Reff〉 ≃ 7.8 pc), and have substantially more scatter in their sizes than in situ metal-rich GCs in the Milky Way and young massive star clusters forming in M83 (〈Reff〉 ≃ 2.5 pc). We show that the size, scatter, and survival of GCs in dwarf galaxies are all consistent with them having evolved in a constant density core, or a potential that has undergone a cusp-core transformation, but not in a dark matter cusp.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
NameEmailORCID
Orkney, M D Am.d.orkney@surrey.ac.uk
Read, J Ij.read@surrey.ac.uk
Petts, J Aj.petts@surrey.ac.uk
Gieles, Mm.gieles@surrey.ac.uk
Date : 26 June 2019
Funders : European Research Council (ERC)
DOI : 10.1093/mnras/stz1625
Grant Title : CLUSTERS
Copyright Disclaimer : © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
Depositing User : Clive Harris
Date Deposited : 03 Sep 2019 09:16
Last Modified : 03 Sep 2019 09:16
URI: http://epubs.surrey.ac.uk/id/eprint/852523

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