An Optical and Radio Survey of the Nuclei of Bright Galaxies - Activity in the Normal Galactic Nuclei

A survey was made of typical galactic nuclei in a statistically complete sample of roughly 90 bright galaxies in order to detect compact nonthermal radio sources and emission-line regions not excited by normal stars. A class of Low Ionization Nuclear Emission-line Regions (Liners) occurring commonly in typical galactic nuclei is defined, whose principal characteristic is the relative strength of emission lines from species of low ionization state, and whose luminosity (L(H alpha) of about 10 to the 38th to 10 to the 40th ergs/s) is more similar to that of a typical giant H II region than to the Seyfert galaxies and QSOs. In addition, 13 Compact Nuclear Radio Sources (CNRS) have been detected in the sample; the presence and strength of a Liner is found to be statistically related to the presence and strength of a CNRS.