Small Steep-Spectrum Sources: Jets Colliding with Ambient Gas

A large fraction of sources in flux limited radio samples consists of compact steep spectrum (CSS) sources (Fanti et al. 1987). These objects have their dominant emission on kiloparsec scales and are found in a variety of active galaxies, including Seyfert II's, peculiar galaxies and quasars. Observations of very nearby CSS sources have shown good correlations between their complex radio structures and optical emission-line gas suggesting violent interactions between jets and dense gas in their ambient interstellar media (van Breugel et al. 1984). Similar jet/gas interactions may occur in more distant and more powerful CSS sources.