Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Statistical mechanics of collisionless orbits. I. Origin of central
  cusps in dark-matter halos   We present an equilibrium statistical mechanical theory of collisionless
self-gravitational systems with isotropic velocity distributions. Compared to
existing standard theories, we introduce two changes: (1) the number of
possible microstates is computed in energy (orbit) space rather than phase
space and (2) low occupation numbers are treated more appropriately than using
Stirling's approximation. Combined, the two modifications predict that the
relaxed parts of collisionless self-gravitating systems, such as dark-matter
halos, have a differential energy distribution N(E) ~ [exp(phi_0 - E) - 1],
dubbed "DARKexp". Such systems have central power-law density cusps rho(r) ~
r^-1, which suggests a statistical mechanical origin of cusps in simulated
dark-matter halos.

11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th