Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution of the Phase-Space Density of Dark Matter Halos and Mixing
  Effects in Merger Events   Cosmological N-body simulations were performed to study the evolution of the
phase-space density Q = rho/sigma^3 of dark matter halos. No significant
differences in the scale relations Q ~ sigma^(-2.1) or Q ~ M^(-0.82) are seen
for "cold" or "warm" dark matter models. The follow up of individual halos from
z = 10 up to the present time indicate the existence of two main evolutionary
phases: an early and fast one (10 > z > 6.5), in which Q decreases on the
average by a factor of 40 as a consequence of the randomization of bulk motions
and a late and long one (6.5 > z > 0), in which Q decreases by a factor of 20
because of mixing induced by merger events. The study of these halos has also
evidenced that rapid and positive variations of the velocity dispersion,
induced by merger episods, are related to a fast decrease of the phase density
Q.

20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th