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We present improved fits to our treatment of suppression of dielectronicrecombination at intermediate densities. At low densities, most recombinedexcited states eventually decay to the ground state, and therefore the totaldielectronic recombination rate to all levels is preserved. At intermediatedensities, on the other hand, collisions can lead to ionization of higher-lyingexcited states, thereby suppressing the dielectronic recombination rate. Theimproved suppression factors presented here, although highly approximate, allowsummed recombination rate coefficients to be used to intermediate densities.There have been several technical improvements to our previously presentedfits. For H- through B-like ions the activation log densities have beenadjusted to better reproduce existing data. For B-, C-, Al-, and Si-like ionssecondary autoionization is now included. The treatment of densitydiscontinuity in electron excitations out of ground state H-, He-, and Ne-likeions has been improved. These refined dielectronic recombination suppressionfactors are used in the most recent version of the plasma simulation codeCloudy. We show how the ionization and emission spectrum change when thisphysics is included. Although these suppression factors improve the treatmentof intermediate densities, they are highly approximate and are not asubstitution for a complete collisional-radiative model of the ionizationbalance.

the astrophysical journal. supplement series/astrophysical journal. supplement series

Suppression of Dielectronic Recombination Due to Finite Density Effects  II: Analytical Refinement and Application to Density-dependent Ionization  Balances and AGN Broad-line Emission