Properties of globular clusters formed in dark matter mini-halos

TL;DR

This study uses high-resolution simulations to distinguish properties of globular clusters formed with dark matter mini-halos from those without, revealing differences in tidal shielding, velocity anisotropy, and dynamical evolution.

Contribution

It provides new insights into how dark matter mini-halos influence globular cluster dynamics and offers parametric profiles for future modeling.

Findings

Dark matter mini-halos can shield GCs from tidal stripping.

GCs with DM mini-halos tend to have more radial velocity anisotropy.

Dynamical friction causes a bimodal distribution in GCs' orbital properties.

Abstract

We seek to differentiate dynamical and morphological attributes between globular clusters (GCs) that were formed inside their own dark matter (DM) mini-halo, and those who were not. We employ high resolution full N-body simulations on GPU of GCs with and without a DM mini-halo, orbiting a Fornax-like dwarf galaxy. For GCs with DM, we observe that this dark extra mass triggers a tidal radius growth that allows the mini-halo to act as a protective shield against tidal stripping, being itself stripped beforehand the stars. We demonstrate that this shielding effect becomes negligible when the tidal radius is smaller than the half-mass radius of the mini-halo. Contrary to previous predictions, we found that the inflation of outer stellar velocity dispersion profiles is expected for GCs with and without a mini-halo, as a result of the host's tidal field. Moreover, we observe that GCs with a DM mini-halo should have, in general, relatively more radial outer velocity anisotropy profiles throughout all their orbits, smaller degrees of internal rotation, and as a consequence of the latter, smaller ellipticities for their stellar distribution. Due to dynamical friction, we observe a clear bimodal evolutionary distribution of GCs with and without DM in the integrals of motion space and show that for GCs originally embedded in DM, this method is not reliable for association with previous accretion events. Finally, we provide parametric mass profiles of disrupted DM mini-halos from GCs to be used in Jeans modelling and orbital integration studies.