Nuclear Luminosities and Radio Loudness of Seyfert Nuclei

Historically, Seyfert nuclei have been considered to be radio-quiet active galactic nuclei (AGNs). We question this widely held assumption by showing that the distribution of the radio-to-optical luminosity ratio, R ≡ L ν (6 cm)/ L ν ( B ), when properly measured for the nuclear component, places the majority of type 1 Seyfert nuclei in the category of radio-loud AGNs, defined here as objects with R ≥ 10. This result is further strengthened by strong correlations found between radio power and optical continuum and emission-line luminosities, as has been established previously for more powerful AGNs. We also present a new calibration of the relation between optical continuum and Balmer emission-line luminosities valid in the regime of low-luminosity AGNs.