ARE SEYFERT NARROW-LINE REGIONS POWERED BY RADIO JETS

We argue that the narrow-line regions (NLRs) of Seyfert galaxies are p owered by the transport of energy and momentum by the radio-emitting j ets. This implies that the ratio of the radio power to jet energy flux is much smaller than is usually assumed for radio galaxies. This can be partially attributed to the smaller ages (similar to-10(6) yr) of S eyferts compared to radio galaxies, but one also requires that either the magnetic energy density is more than 1 order of magnitude below th e equipartition value or, more likely, that the internal energy densit ies of Seyfert jets are dominated by thermal plasma, as distinct from the situation in radio galaxy jets where the jet plasma is generally t aken to be nonthermally dominated. If one assumes that the internal en ergy densities of Seyfert jets are initially dominated by relativistic plasma, then an analysis of the data on jets in five Seyfert galaxies shows that all but one of these would have mildly relativistic jet ve locities near 100 pc in order to power the respective narrow-line regi ons. However, observations of jet-cloud interactions in the NLR provid e additional information on jet velocities and composition via the mom entum budget. Our analysis of a jet-cloud interaction in NGC 1068, 24 pc from the core implies a shocked jet pressure much larger than the m inimum pressure of the radio knot, a velocity (probably accurate to wi thin a factor of a few) similar to 0.06c (18,000 km s(-1)), and a temp erature of thermal gas in the jet similar to 10(9) K, implying mildly relativistic electrons but thermal protons. The estimated jets velocit y is proportional to the jet energy flux and provides an independent a rgument that the energy flux in the northern NGC 1068 jet is much grea ter than previously supposed and is capable of providing significant e nergy input to the narrow line region. The jet mass flux at this point similar to 0.5 M-circle dot yr(-1), is 1 oder of magnitude higher tha n the mass accretion rate similar to 0.05 M-circle dot yr(-1) estimate d from the bolometric luminosity of the nucleus, strongly indicating e ntrainment into the jet and accompanying deceleration. Consequently, t he jet velocity near the black hole is possibly mildly relativistic. W e estimate an initial jet mass flux similar to 0.02 M-circle dot yr(-1 ) which is comparable to the mass accretion rate. This mass flux is co nsistent with the densities inferred for accretion disk coronae from h igh energy observations, together with an initially mildly relativisti c velocity and an initial jet radius of order 10 gravitational radii.