0 Assigned ID: 877 ----- Attempting Submission 1 (Fri Apr 11 21:35:24 GMT 2014) ----- The Cycle 21 large program, "Mapping the AGN Broad-line region by reverberation", will produce the definitive line-continuum reverberation dataset. These HST observations should "clarify the nature of the broad-line region, its role in the apparently complicated accretion/outflow process, and determine definitively the veracity and accuracy of the AGN reverberation-based black hole masses". This proposal aims to improve Cloudy simulations of the dense gas emitting the spectrum so that photoionization theory can meet the challenge posed by these new observations. Two specific advances, implementing physical processes now expected to be important, are proposed. The first involves electron scattering enhancement of H I lines. The lines will be broadened and enhanced by scattering off warm (8 000 K) electrons in the extended neutral gas deep within the cloud or disk, affecting both the line profile and intensity. The second involves collisional suppression of dielectronic recombination, the dominant process responsible for recombination of heavy-element UV lines such as C IV 1549, C III] 1909, Mg II 2798, etc. This is made possible by access to a large body of atomic rates within OpenADAS, and will impact predictions of essentially the entire Broad-line region spectrum. Both advances will become part of Cloudy, a publically available and widely used plasma simulation code. AGN/QUASARS Default Legacy false false false false true SUPPORTED