Globular clusters as tracers of the host galaxy mass distribution: the Fornax dSph test case

Abstract

The Fornax dwarf spheroidal galaxy is the most massive satellites of the Milky Way, claimed to be embedded in a huge dark matter halo, and the only among the Milky Way satellites hosting five globular clusters. Interestingly, their estimated masses, ages and positions seem hardly compatible with the presence of a significant dark matter component, as expected in the $\Lambda$ CDM scheme. Indeed, if Fornax would have a CDM halo with a standard density profile, all its globular clusters should have sunk to the galactic centre many Gyr ago due to dynamical friction. Due to this, some authors proposed that the most massive clusters may have formed out of Fornax and later tidally captured. In this paper we investigate the past evolution of the Fornax GC system by using both a recently developed, semi-analytical treatment of dynamical friction and direct $N$-body simulations of the orbital evolution of the globular clusters within Fornax and of Fornax galaxy around the Milky Way. Our results suggest that an "in-situ" origin for all the clusters is likely if their observed positions are close to their spatial ones and their orbits are almost circular. Moreover, the Milky Way seems to accelerate the GC decay reducing the decay time of $15\%$. Nevertheless, our results indicate that the GCs survival probability exceeds $50\%$, even in the case of cuspy density profiles. We conclude that more detailed data are required to shed light on the Fornax dark matter content, to distinguish between a cuspy or a cored profile.

9 pages, 8 tables, 5 figures in Monthly Notices of the Royal Astronomical Society 2016

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Cited by in corpus (9)

• Lack of nuclear clusters in dwarf spheroidal galaxies: implications for massive black holes formation and the cusp/core problem
• A dwarf-dwarf merger and dark matter core as a solution to the Globular Cluster problems in the Fornax dSph
• On the Orbital Decay of Globular Clusters in NGC1052-DF2: Testing a Baryon-Only Mass Model
• The MEGaN project I. Missing formation of massive nuclear clusters and tidal disruption events by star clusters - massive black hole interactions
• Fornax globular cluster distributions: implications for the cusp-core problem
• The survival of globular clusters in a cuspy Fornax
• The spatial distribution of globular clusters in dwarf spheroidal galaxies and the timing problem
• Are we observing a NSC in course of formation in the NGC 4654 galaxy?
• Nuclear star clusters as probes of dark matter halos: the case of the Sagittarius Dwarf Spheroidal Galaxy