A Far-Infrared Spectral Sequence of Galaxies: Trends and Models

摘要: We present a framework for the interpretation of far-infrared spectra galaxies in which we have expanded model parameters compared with previous work by varying ionization parameter $U$, column density $N$(H), and gas at cloud face $n$(H$^{+}$) central starburst or AGN. compare these models carried out $Cloudy$ spectral synthesis code to trends line-to-total luminosity ratios, fine-structure line IRAS colors, OH H$_{2}$O densities found well-studied sample ten nearby from Bright Galaxy Sample infrared luminosities greater than 10$^{10}$ L$_{\odot}$ 60 micron fluxes equal that ULIRG Arp 220. find sequence extending normal starburst-type emission ULIRG-type absorption-dominated significant absorption excited levels, can be best explained simultaneously increasing hydrogen density, as low 10$^{21}$ cm$^{-2}$ high 10$^{24.8}$ greater, parameter, 10$^{-4}$ 1. The reproduce most sequence, while AGN are somewhat better able produce Our results suggest molecular ISM ULIRG-like, systems is located close least partially obscures source power throughout much far-infrared, must taken into account order properly interpret diagnostics both their sources feedback.