Embedding globular clusters in dark matter minihalos solves the cusp-core and timing problems in the Fornax dwarf galaxy

Abstract

We use a fully GPU $N$-body code to demonstrate that dark matter minihalos, as a new component of globular clusters, resolve both the timing and cusp-core problems in Fornax if the five (or six) globular clusters were recently accreted ($\leq$ 3 Gyr ago) by Fornax. Under these assumptions, infall of these globular clusters does not occur and no star clusters form in the centre of Fornax in accordance with observations. We find that crossings of globular clusters that have DM minihalos near the Fornax centre induce a cusp-to-core transition of the dark matter halo and hence resolve the cusp-core problem in this dwarf galaxy. The dark matter core size depends on the frequency of globular cluster crossings. Our simulations clearly demonstrate also that between the passages, the dark matter halo can regenerate its cusp. Moreover, our models are in good agreement with constraints on the dark matter masses of globular clusters as our clusters lose a large fraction of their initial dark matter minihalos. These results provide circumstantial evidence for the universal existence of dark matter halos in globular clusters.