Two‐Photon Transitions and Continuous Emission from Hydrogenic Species

Abstract

We discuss the implementation of two-photon emission and absorption in Cloudy, a general-purpose photoionization and radiative transfer code. We now include induced two-photon absorption between the 1s and 2s levels of hydrogen and hydrogen-like ions and between the 1 1 S and 2 1 S levels of the He-like isoelectronic sequence. We show sample calculations predicting the full emitted continuum and have implemented a method to allow this continuum to be saved in FITS format and reused in other applications.