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Probing dark matter with star clusters: a dark matter core in the ultra-faint dwarf Eridanus II

Contenta, Filippo, Balbinot, Eduardo, Petts, James, Read, Justin, Gieles, Mark, Collins, Michelle, Peñarrubia, Jorge, Delorme, Maxime and Gualandris, Alessia (2018) Probing dark matter with star clusters: a dark matter core in the ultra-faint dwarf Eridanus II Monthly Notices of the Royal Astronomical Society.

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We present a new technique to probe the central dark matter (DM) density profile of galaxies that harnesses both the survival and observed properties of star clusters. As a first application, we apply our method to the `ultra-faint' dwarf Eridanus II (Eri II) that has a lone star cluster ~45 pc from its centre. Using a grid of collisional N-body simulations, incorporating the effects of stellar evolution, external tides and dynamical friction, we show that a DM core for Eri II naturally reproduces the size and the projected position of its star cluster. By contrast, a dense cusped galaxy requires the cluster to lie implausibly far from the centre of Eri II (>1 kpc), with a high inclination orbit that must be observed at a particular orbital phase. Our results imply that either a cold DM cusp was `heated up' at the centre of Eri II by bursty star formation, or we are seeing an evidence for physics beyond cold DM.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Peñarrubia, Jorge
Date : 2018
Funders : Science and Technology Facilities Council (STFC)
Copyright Disclaimer : © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
Uncontrolled Keywords : Stars: kinematics and dynamics; Globular clusters: general; Galaxies: structure; Galaxies: dwarf; Galaxies: individual: Eridanus II; Galaxies: haloes; Dark matter
Depositing User : Clive Harris
Date Deposited : 16 Feb 2018 09:35
Last Modified : 11 Dec 2018 11:23

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