A DISTINCTIVE DISK-JET COUPLING IN THE SEYFERT-1 ACTIVE GALACTIC NUCLEUS NGC 4051

Abstract

We report on the results of a simultaneous monitoring campaign employing eight Chandra X-ray (0.5-10 keV) and six Very Large Array/Extended Very Large Array (8.4 GHz) radio observations of NGC 4051 over seven months. Evidence for compact jets is observed in the 8.4 GHz radio band; this builds on mounting evidence that jet production may be prevalent even in radio-quiet Seyferts. Assuming comparatively negligible local diffuse emission in the nucleus, the results also demonstrate an inverse correlation of L [subscript radio] ∝ L [–0.72±0.04 over X-ray]. If the A configuration is excluded in the case where diffuse emission plays a significant role, the relation is still L[subscript radio] ∝ L[-0.12±0.05 over X-ray]. Current research linking the mass of supermassive black holes and stellar-mass black holes in the "low/hard" state to X-ray luminosities and radio luminosities suggests a "fundamental plane of accretion onto black holes" that has a positive correlation of L [subscript radio] ∝ L [0.67±0.12 over X-ray]. Our simultaneous results differ from this relation by more than 11σ (6σ excluding the A configuration), indicating that a separate mode of accretion and ejection may operate in this system. A review of the literature shows that the inverse correlation seen in NGC 4051 is seen in three other black hole systems, all of which accrete at near 10% of their Eddington luminosity, perhaps suggesting a distinct mode of disk-jet coupling at high Eddington fractions. We discuss our results in the context of disks and jets in black holes and accretion across the black hole mass scale.