Institution(s): 1. Korea Institute for Advanced Study
We will introduce an excursion set model for the evolution of halo spin from cosmological N-body simulations. A stochastic differential equation is derived from the definition of halo spin and the distribution of angular momentum changes are measured from simulations. The log-normal distribution of halo spin is found to be a natural consequence of the stochastic differential equation and the resulting spin distribution is found be a function of local environments, halo mass, and redshift.