Tidal interactions and infrared-bright QSOs

Abstract

Deep direct images of five IRAS-selected QSOs with similar IR luminosities and spectral indices have been analyzed. The present objects possess IR luminosities similar to those of the IRAS flux-lined sample of ultraluminous galaxies, but have IR spectral indices similar to those of normal QSOs. Four of the objects are in strong tidal interaction and have blue host galaxies and reddened nuclei. It is suggested that these objects are QSOs and AGN in an intermediate stage of their activity, which lies between that of ultraluminous galaxies and optically selected QSOs.