Probing dark matter with star clusters: a dark matter core in the ultra-faint dwarf Eridanus II
Probing dark matter with star clusters: a dark matter core in the ultra-faint dwarf Eridanus II
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DOI：
10.1093/mnras/sty424
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发表时间：
2017-05
影响因子：
4.8
通讯作者：
Filippo Contenta;E. Balbinot;J. A. Petts;J. Read;M. Gieles;M. Collins;J. Peñarrubia;Maxime Delorme;A. D. O. Physics;University of Surrey;Institute for Astronomy;U. Edinburgh;R. Observatory;B. Hill
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作者：
Filippo Contenta;E. Balbinot;J. A. Petts;J. Read;M. Gieles;M. Collins;J. Peñarrubia;Maxime Delorme;A. D. O. Physics;University of Surrey;Institute for Astronomy;U. Edinburgh;R. Observatory;B. Hill
我们提出了一种新的技术来探测星系的中心暗物质（DM）密度分布，该技术利用了星团的生存和观测特性。作为第一个应用，我们将我们的方法应用于“超暗”矮星Eridanus II (Eri II)，它的中心有一个离它45 pc的孤星团。利用碰撞n体模拟网格，结合恒星演化、外部潮汐和动态摩擦的影响，我们表明Eri II的DM核心自然地再现了其星团的大小和投影位置。相比之下，密集的尖头星系要求星系团远离Eri II的中心（bbb101kpc），具有高倾角轨道，必须在特定的轨道阶段观察到。我们的研究结果表明，要么是在Eri II的中心，一个冷DM尖端被恒星形成的爆发“加热”了，要么是我们看到了冷DM之外的物理证据。
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.