A new method to constrain the origins of dark matter-free galaxies and their unusual globular clusters

Abstract

We present a novel method to constrain the past collisional evolution of observed globular cluster (GC) systems, in particular their mass functions. We apply our method to a pair of galaxies hypothesized to have recently undergone an episode of violent relaxation due to a strong galaxy-galaxy interaction, namely NGC 1052-DF2 and NGC 1052-DF4. We begin by exploring the observational evidence for a collisional origin for these two recently discovered ultra-diffuse galaxies observed in the NGC 1052 group, posited in the literature to be dark matter (DM)-free. We compute the timescales for infall to the central nucleus due to dynamical friction (DF) for the GCs in these galaxies, using the shortest of these times to constrain how long ago a galaxy-galaxy interaction could have occurred. We go on to quantify the initial GC numbers and densities needed for significant collisional evolution to occur within the allotted times, and show that, if the hypothesis of a previous galaxy-galaxy interaction is correct, a paucity of low-mass GCs should be revealed by deeper observational surveys. If any are found, they should be more spatially extended than the currently observed GC population. Finally, we apply our method to these galaxies, in order to illustrate its efficacy in constraining their dynamical evolution. Our results motivate more complete observations of the GC luminosity functions in these galaxies, in addition to future studies aimed at combining the method presented here with a suite of numerical simulations in order to further constrain the origins of the curious GC populations in these (and other) galaxies.

12 pages, 5 figures, 2 table, accepted by ApJ

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Cited by in corpus (8)

• A Tip of the Red Giant Branch Distance of $22.1\pm 1.2$ Mpc to the Dark Matter Deficient Galaxy NGC1052-DF2 from 40 Orbits of Hubble Space Telescope Imaging
• A Complex Luminosity Function for the Anomalous Globular Clusters in NGC1052-DF2 and NGC1052-DF4
• Globular clusters as tracers of the dark matter content of dwarfs in galaxy clusters
• On the Evolution of the Globular Cluster System in NGC 1052-DF2: Dynamical Friction, Globular-Globular Interactions and Galactic Tides
• Evolution of subhalo orbits in a smoothly-growing host halo potential
• Testing the galaxy collision induced formation scenario for the trail of dark matter deficient galaxies with the susceptibility of globular clusters to the tidal force
• Enigmatic Velocity Dispersions of Ultra-Diffuse Galaxies in Light of Modified Gravity Theories and Radial Acceleration Relation
• On the Tidal Formation of Dark Matter Deficient Galaxies