Statistical mechanics of collisionless orbits. IV. Distribution of angular momentum

Understand

It has been shown in previous work that DARKexp, which is a theoretically derived, maximum entropy, one shape parameter model for isotropic collisionless systems, provides very good fits to simulated and observed dark-matter halos.

• Specifically, it fits the energy distribution, N(E), and the density profiles, including the central cusp.
• Here, we extend DARKexp N(E) to include the distribution in angular momentum, L^2, for spherically symmetric systems.
• First, we argue, based on theoretical, semi-analytical, and simulation results, that while dark-matter halos are relaxed in energy, they are not nearly as relaxed in angular momentum, which precludes using maximum entropy to uniquely derive N(E,L^2).