Numerical simulations of photoionized plasmas: Applications to astrophysical and laboratory environments

A wide variety of astrophysical objects, ranging from newly formed stars to accreting black holes, produce ionizing radiation. Nearby material will reprocess these photons into other forms of light. Depending on the geometry, we will observe such gas through either an emission or absorption line spectrum. Such clouds are detected across the electromagnetic spectrum and detailed analysis can reveal such vital parameters as the composition of the gas and the form of the ionizing radiation field. The gas is in a non-equilibrium state due to its low density and the presence of a wide range of non-thermal energy sources. The spectrum is typically analyzed with the help of large-scale numerical simulations. This paper describes recent developments of Cloudy, a code that performs such simulations, and outlines applications to star forming regions, active galactic nuclei, and laboratory plasmas.