http://arxiv.org/abs/1903.06717
In this paper, we explore the observational evidence for a collisional origin for the recently discovered dark matter (DM)-free ultra-diffuse galaxies observed in the NGC 1052 group. We have computed the timescales for infall to the central nucleus due to dynamical friction (DF) for the globular clusters (GCs) in NGC 1052-DF2 and NGC 1052-DF4. We find that two out of ten GCs in NGC 1052-DF2 and one out of seven in NGC 1052-DF4 have DF timescales less than a Hubble time. We explore the possibility that this could be evidence for recent galaxy-galaxy interactions, that both stripped NGC 1052-DF2/NGC 1052-DF4 of their DM halos and either fundamentally altered the orbits of their GCs or triggered their formation. Our results are more consistent with the former scenario, pushing most GCs on to highly eccentric orbits and/or delivering them deeper in their host galactic potential, triggering significant collisional evolution. If correct, these would be the first GC populations discovered to have undergone significant collisional evolution \textit{after} their initial formation, ejecting preferentially low-mass GCs and perhaps even resulting in some GC-GC collisions, contributing to the observed top-heavy GC mass functions and centrally concentrated positions.
N. Leigh and G. Fragione
Tue, 19 Mar 19
25/100
Comments: 9 pages, 4 figures, 1 table
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