M.L. Luhman 1 - S. Satyapal 2 - J. Fischer1 - M.G. Wolfire 3
We compare ISO LWS observations of the [CII] 158 
m and, where
observed, the [OI] 63 and 146 m fine-structure lines in a sample of
ultraluminous infrared galaxies (ULIGs) to the results of recent
theoretical models of extragalactic photodissociation regions (PDRs). The
PDR models are up-to-date versions of those of Wolfire, Tielens, &
Hollenbach (1990), which include, among other things, the photoelectric
heating effects of small grains/PAHs. Applying the models to Arp 299, we
address the PDR origin of the fine-structure lines and the physical
properties of the PDR component. In our sample of ULIGs, the [CII] line
flux is ~ 10% of that found in normal and starburst galaxies in the
local universe. We use the PDR models, along with the results of
photoionization models, to address possible origins for the [CII] deficit.
Postscript version