The Dynamical Structure of Dark Matter Halos with Universal Properties
Abstract
N-body simulations have unveiled several apparently universal properties of dark matter halos, including a cusped density profile, a power-law pseudo-phase-space density ρ/σ3 r , and a linear β-γ relation between the density slope and the velocity anisotropy. We present a family of self-consistent phase-space distribution functions (DFs) F(E, L), based on the Dehnen-McLaughlin Jeans models, that incorporate these universal properties very accurately. These DFs, derived using a quadratic programming technique, are analytical, positive, and smooth over the entire phase space and are able to generate four-parameter velocity anisotropy profiles β(r) with arbitrary asymptotic values β0 and β∞. We discuss the orbital structure of six radially anisotropic systems in detail and argue that, apart from its use for generating initial conditions for N-body studies, our dynamical modeling provides a valuable complementary approach to understand the processes involved in the formation of dark matter halos.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2009
- DOI:
- 10.1088/0004-637X/690/2/1280
- arXiv:
- arXiv:0809.0901
- Bibcode:
- 2009ApJ...690.1280V
- Keywords:
-
- dark matter;
- methods: analytical;
- Astrophysics
- E-Print:
- 12 pages, 5 figures, accepted for publication in ApJ