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The origin of the low luminosity radio emission in radio-quiet AGN, isunknown. The detection of a positive correlation between the radio and X-rayemission would imply a jet-like origin, similar to that seen in `hard state'X-ray binary systems. In our previous work, we found no believable radiovariability in the well known X-ray bright Seyfert 1 galaxy NGC 4051, despitelarge amplitude X-ray variability. In this study we have carefully re-analysedradio and X-ray observations using the same methods as our previous work, weagain find no evidence for core radio variability. In direct contrast to ourfindings, another study claim significant radio variability and a distinctiveanti-correlation between radio and X-ray data for the same source. The otherstudy report only integral flux values and do not consider the effect of thechanging array on the synthesised beam. In both our studies of NGC 4051 we havetaken great care to account for the effect that the changing beam size has onthe measured radio flux and as a result we are confident that our method givesmore accurate values for the intrinsic core radio flux. However, the lack ofradio variability we find is hard to reconcile because radio images of NGC 4051do show jet-like structure. We suggest that the radio structures observed arelikely the result of a previous period of higher radio activity and that thecurrent level of radio emission from a compact nuclear jet is low.

A comprehensive long term study of the radio and X-ray Variability of NGC 4051 Paper II