Radio Sources in Low‐Luminosity Active Galactic Nuclei. I. VLA Detections of Compact, Flat‐Spectrum Cores

We report a high resolution (0: 00 2), 15 GHz survey of a sample of 48 low-luminosity active galactic nuclei with the Very Large Array 1. Compact radio emission has been detected above a flux density of 1. 1 mJy in 57% (17 of 30) of low-ionization nuclear emission-line region (LINER) nuclei and low-luminosity Seyferts. The 2 cm radio power is significantly correlated with the emission-line (O I 6300) luminosity. Using radio fluxes at other frequencies from the literature, we find that at least 15 of the 18 detected radio cores have a flat to inverted spectrum (ff \0. 3, S / ff). While the present observations are consistent with the radio emission originating in star forming regions (the brightness temperatures are 10 2: 5\4: 5 K), higher resolution radio observations of 10 of the detected sources, reported in a companion paper (Falcke et al. 2000), show that the cores are very compact (. pc), of high brightness temperature (T b 10 8 K) and probably. . .