Dissecting the Evolution of Dark Matter Subhaloes in the Bolshoi Simulation

Understand

We present a comprehensive analysis of the evolution of dark matter subhaloes in the cosmological Bolshoi simulation.

• We identify a complete set of 12 unique evolution channels by which subhaloes evolve in between simulation outputs, and study their relative importance and demographics.
• We show that instantaneous masses and maximum circular velocities of individual subhaloes are extremely noisy, despite the use of a sophisticated, phase-space-based halo finder.
• We also show that subhaloes experience frequent penetrating encounters with other subhaloes (on average about one per dynamical time), and that subhaloes whose apo-center lies outside the virial radius of their host (the 'ejected' or 'backsplash' haloes) experience tidal forces that modify their orbits.