Universal structure of two and three dimensional self-gravitating
  systems in the quasi-equilibrium state
  We study a universal structure of two and three dimensional self-gravitating
systems in the quasi-equilibrium state. It is shown numerically that the two
dimensional self-gravitating system in the quasi-equilibrium state has the same
kind of density profile as the three dimensional one. We develop a
phenomenological model to describe this universal structure by using a special
Langevin equation with a distinctive random noise to self-gravitating systems.
We find that the density profile derived theoretically is consistent well with
results of observations and simulations.
