EVOLUTION OF DARK MATTER PHASE-SPACE DENSITY DISTRIBUTIONS IN EQUAL-MASS HALO MERGERS

摘要: We use dissipationless N-body simulations to investigate the evolution of true coarse-grained phase-space density distribution f(x, v) in equal-mass mergers between dark matter (DM) halos. The halo models are constructed with various asymptotic power-law indices ρ ∝ r –γ ranging from steep cusps core-like profiles and we employ estimator "EnBid" developed by Sharma & Steinmetz compute v). adopted force resolution allows robust profile estimates inner ~1% virial radii simulated systems. confirm that merger events result a decrease accordance expectations Mixing Theorems for collisionless demonstrate binary identical DM halos produce remnants retain excellent memories slopes overall shapes their progenitors. robustness holds range orbital energies, variety encounter configurations including sequences several consecutive events, designed mimic hierarchical merging, collisions occurring at different cosmological epochs. If progenitor appreciably indices, find slope shape remnant substantially closer initial system steepest central cusp. These results explicitly mixing is incomplete halos, as it does not erase memory properties. Our also recent analytical predictions Dehnen regarding preservation merging self-gravitating cusps.