Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-06-23
Astrophys.J.634:756-774,2005
Astronomy and Astrophysics
Astrophysics
37 pg, 14 fig. Accepted to ApJ: added two figures and extended discussion. Note that an earlier related paper (conference proc
Scientific paper
10.1086/497133
Although N-body studies of dark matter halos show that the density profiles, rho(r), are not simple power-laws, the quantity rho/sigma^3, where sigma(r) is the velocity dispersion, is in fact a featureless power-law over ~3 decades in radius. In the first part of the paper we demonstrate, using the semi-analytic Extended Secondary Infall Model (ESIM), that the nearly scale-free nature of rho/sigma^3 is a robust feature of virialized halos in equilibrium. By examining the processes in common between numerical N-body and semi-analytic approaches, we argue that the scale-free nature of rho/sigma^3 cannot be the result of hierarchical merging, rather it must be an outcome of violent relaxation. The empirical results of the first part of the paper motivate the analytical work of the second part of the paper, where we use rho/sigma^3 proportional to r^{-alpha} as an additional constraint in the isotropic Jeans equation of hydrostatic equilibrium. Our analysis shows that the constrained Jeans equation has different types of solutions, and in particular, it admits a unique ``periodic'' solution with alpha=1.9444. We derive the analytic expression for this density profile, which asymptotes to inner and outer profiles of rho ~ r^{-0.78}, and rho ~ r^{-3.44}, respectively.
Austin Crystal G.
Babul Arif
Barnes Eric I.
Dalcanton Julianne J.
Williams Liliya L. R.
No associations
LandOfFree
Semi-analytical dark matter halos and the Jeans equation does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Semi-analytical dark matter halos and the Jeans equation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semi-analytical dark matter halos and the Jeans equation will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-581721