Time-Dependent Photoionization in a Dusty Medium. III: The effect of dust on the photoionization of metals

We use the time-dependent photoionization and dust destruction code developed by Perna & Lazzati (2002) to study the time evolution of the medium in a dusty gaseous cloud illuminated by a bright central source that sets on at time zero. We study the case of a bright source, which lasts for a time scale much smaller than the recombination and dust creation time scales. For this reason an equilibrium is never reached. We show that the presence of dust and its properties, such as its composition, can have a big effect on the time scale for the evaporation of the soft X-ray absorption, in particular for ionizing sources with hard spectra. We discuss the profile of evaporation of the soft X-ray absorbing column, as well as how the apparent ionization state of the cloud evolves in time. We finally consider the apparent metallicity of the cloud that is left behind as a function of the cloud and ionizing source properties.