Three-dimensional Monte Carlo simulations of ionized nebulae

A three-dimensional self-consistent photoionization code is developed using Monte Carlo techniques in order to build realistic models of photoionized nebulae of arbitrary geometry and density distribution. The gaseous region is mapped onto a cuboidal Cartesian grid composed of numerous cells. The physical conditions at each cell are calculated taking into account the optical depth and diffuse radiation which depend on the other cells. This is done by locally simulating the individual processes of ionization and recombination. This paper contains a brief description of the code and preliminary results for the Meudon-Lexington benchmark HII region. Future work and possible applications of the code are also discussed.