The extended narrow line region in MKN 79. II. Modelling.

We present photoionization modelling of the Extended Narrow Line Region (ENLR) in Mkn 79 based on long-slit spectra presented in our previous paper (Nazarova et al. 1996). The ENLR has been modelled with two gas components: a system of high density clouds embedded in a low density gas envelope. The ENLR line fluxes have been calculated allowing for attenuation of the nuclear ionizing continuum as a function of distance from the centre. The diffuse continuum emission from the low density gas is also included as an important secondary source of ionization. We show that this multi-component gas model can successfully reproduce the observed line fluxes and line ratios in the ENLR of Mkn 79 assuming a central source luminosity of 6.6x10^52^photons/s, consistent with the dereddened nuclear luminosity. The predicted reflected continuum from the ENLR gas is also in agreement with the observed extended blue continuum emission.