2010/08/31 by Phillip Zukin, Edmund Bertschinger · 10 citations
Mathematics · Physics and Astronomy · #Anisotropy #Astrophysics #Astrophysics and Star Formation Studies #Asymptote #Classical mechanics #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Halo #Kinetic energy #Mathematics #Mechanics #Phase space #Physics #Quantum mechanics #RADIUS #Virial theorem #astro-ph.CO
paper · pdf · doi:10.1103/physrevd.82.104045
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 82(10) (American Physical Society) · 11 pages, 4 figures. Accepted by PRD
openalex publication_date 2010/11/19 · arxiv created 2010/12/01 · arxiv updated 2010/12/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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.