Velocity Structure of Self-Similar Spherically Collapsed Halos

Abstract

Using a generalized self-similar secondary infall model, which accounts for tidal torques acting on the halo, we analyze the velocity profiles of halos in order to gain intuition for N-body simulation results. We analytically calculate the asymptotic behavior of the internal radial and tangential kinetic energy profiles in different radial regimes. We then numerically compute the velocity anisotropy and pseudo-phase-space density profiles and compare them to recent N-body simulations. For cosmological initial conditions, we find both numerically and analytically that the anisotropy profile asymptotes at small radii to a constant set by model parameters. It rises on intermediate scales as the velocity dispersion becomes more radially dominated and then drops off at radii larger than the virial radius where the radial velocity dispersion vanishes in our model. The pseudo-phase-space density is universal on intermediate and large scales. However, its asymptotic slope on small scales depends on the halo mass and on how mass shells are torqued after turnaround. The results largely confirm N-body simulations but show some differences that are likely due to our assumption of a one-dimensional phase space manifold.

11 pages, 4 figures. Accepted by PRD

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Cited by in corpus (10)

• Self-Similar Dynamical Relaxation of Dark Matter Halos in an Expanding Universe
• Predicting the density profiles of the first halos
• Phase-space structure of protohalos: Vlasov versus Particle-Mesh
• Constraints on shear and rotation with massive galaxy clusters
• Dark matter halo's and self similarity
• Cold dark matter protohalo structure around collapse: Lagrangian cosmological perturbation theory versus Vlasov simulations
• The gravitational force field of proto-pancakes
• Effects of Angular Momentum on Halo Profiles
• Dark matter halo dynamics in 2D Vlasov Simulations: a self-similar approach
• Longitudinal crossover and the dynamics of uniform electron ellipsoids focused by linear chirp