modified versions of the cosmological volume containing ErisDark are used as initial conditions for the gravity calculation runs down to redshift 0. ChaNGa was used to carry out these new cosmological runs. The code ChaNGa uses a fast hierachical oct-tree gravity solver, and is based on the Charm++ parallel programming infrastructure ([@CharmppPPWCPP96]). It leverages the object-based virtualization and data-driven style of computation inherent in Charm++ to adaptively overlap communication and computation and achieve high levels of resource utilization on large systems ([@changa2008], [@changa2010]). The Charm++ load balancing infrastructure is used to distribute pieces of this tree across processors. The leaf nodes are buckets that contain several particles (usually 8 to 32) whose force calculations are collectively optimized. At each level of the tree, multipoles are calculated to speed distant force evaluations. Time adaptivity is achieved by assigning individual timesteps to particles. A special load balancer was developed by the UIUC Charm++ team to efficiently handle the resulting processor load imbalance ([@2015ComAC...2....1M]).

Results and data analysis {#sec3}
=========================

The resulting raw simulation data is analized using the AHF in the same manner as performed with the original ErisDark simulation data. From the set of halos generated by the AHF code, the 