Abstract:
The interstellar medium (ISM) plays a crucial role in the cycle of matter in every galaxy. The gas and dust that is present in the ISM is usually very far removed from (local) thermodynamic equilibrium, and in some cases may also not be in a steady-state equilibrium with its surroundings. The physics of this material is complex and you need a sophisticated numerical code to study it. For this purpose the open-source photoionization code Cloudy was created. It models the physical state of the gas and predicts the spectrum that it emits. Cloudy is continually being developed to improve the treatment of the microphysical processes and the database of fundamental data that it uses. In this paper we will discuss how we are developing the code to improve our high-density predictions by implementing better collisional-radiative models for all ions. We will also briefly discuss the experimental mode in Cloudy to model gas that is not in steady-state equilibrium and present a preliminary model of recombining gas in a planetary nebula that is on the cooling track. We finish with a short discussion of how we are speeding up the code by using parallelization.
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