Globular Clusters in a Cosmological N-body Simulation

Abstract

Stellar dynamical model globular clusters are introduced into reconstituted versions of the dark matter halos of the Via Lactea II (VL-2) simulation to follow the star cluster tidal mass-loss and stellar stream formation. The clusters initially evolve within their local sub-galactic halo, later being accreted into the main halo. Stars are continually removed from the clusters, but those that emerged in the sub-galactic halos are dispersed in a wide stream when accreted into the main halo. Thin tidal streams that survive to the present can begin to form once a cluster is in the main halo. A higher-redshift start places the star clusters in denser halos, where they are subject to stronger tides leading to higher average mass-loss rates. A z  = 3 start leads to a rich set of star streams, with nearly all within 100 kpc having a remnant progenitor star cluster in the stream. In contrast, with a z  = 8 start, all star clusters that are accreted onto the main halo are completely dissolved. These results are compared to the available data on Milky Way streams, where the majority of streams do not have clearly associated globular clusters, which, if generally true, suggests that there were at least twice as many massive globular clusters at high redshift.