THE RADIO PROPERTIES OF SEYFERT GALAXIES IN THE 12 MICRON AND CfA SAMPLES

摘要

We report the results of 20, 6, and 2 cm VLA and 1.5 cm OVRO observations of two similar radio-quiet active galaxy and quasar (AGN) samples: the optically selected CfA Seyfert galaxies and the bolo-metric flux-limited 12 μm active galaxy sample. Every object observed was detected at 6 cm. Only ～6%-8% of the 12 μm sample Seyfert galaxies (three to four objects) are radio-loud (and none of the CfA sample), as compared to 15%-20% for the Bright Quasar Survey quasars. These radio-loud objects are compact and have flat spectra, distinguishing them from the more common radio-quiet objects. The 6-20 cm slopes of the Seyfert 1's and 2's are similar, with average values of < α_(6 cm)~(20) > = -0.66 and -0.71, respectively. Although several Seyfert 1's are significantly flatter than this in their 6-20 and/or 1.5-6 cm slopes, there is no systematic trend for either Seyfert type to display upward or downward spectral curvature. Excluding the radio-loud quasars, the integrated 6 cm radio luminosity is linearly proportional to the 60 μm luminosity over several orders of magnitude, with on average twice the radio power of normal spirals of the same far-infrared power. About half of the objects show extended 6 cm emission, contributing on average 33% of the total flux. Thus the luminosities of these extended components alone are comparable to normal spirals of similar infrared luminosities. The 12 μm sample radio luminosity function is slightly higher than that of the CfA sample. The integrated space density of Seyfert 2's is ～2 times that of Seyfert 1's over their common range in luminosity. In terms of the standard unified model, this ratio in space density corresponds to a typical half-angle of the torus of θ ～ 48°.