A SAMPLE OF OPTICALLY FAINT INFRARED LUMINOUS GALAXIES

We describe and discuss the optical and FIR properties of a sample of infrared luminous galaxies. The details of a subsample of eight object s as well as the optical identification of all 99 sources are given in two previous papers. Here we present the redshift and luminosity dist ributions and derive temperature and mass range of the IR emitting dus t. Furthermore a summary of the optical line characteristics and spati al extent of line emission is given. Our analysis of the morphological peculiarities and the spectroscopic data strongly argue for interacti on as the most likely trigger mechanism of the enhanced activity. Star bursts are the most general heating source and excitation scenario for our sample. We have found four new ultra-luminous IR galaxies in our survey and discuss their stage within the evolutionary scenario from s tarburst galaxies to quasars.