Far-Infrared Spectroscopy Of Normal Galaxies With Iso-Lws

The deficiency of [CII] (158 ?￥m) line emission inmany normal and ultraluminous galaxies is one ofthe major surprises from ISO-LWS observations. Weshow that this is not an isolated phenomenon: thereis a smooth decline in L [CII] =L FIR ratio with increasingdust temperature (as indicated by far-infraredcolors F (60?￥m)=F (100?￥m)) and star-formation activity(indicated by L FIR =LB ), independent of theirluminosity or morphology. In a sample of 60 normalgalaxies, these trends span a...