THE FAINTEST SEYFERT RADIO CORES REVEALED BY VLBI

摘要: In this Letter, we report on dual-frequency European VLBI Network observations of the faintest and least luminous radio cores in Seyfert nuclei, going to sub-millijansky flux densities luminosities around 1019 W Hz–1. We detect emission from nuclear region four galaxies (NGC 4051, NGC 4388, 4501, 5033), while one 5273) is undetected at level ~100 μJy. The detected compact nuclei have rather different properties: spectral indices range steep (α>0.7) slightly inverted (α = –0.1), brightness temperatures vary TB 105 K larger than 107 K, are either extended or unresolved, case accompanied by lobe-like features 4051). sense, diverse underlying physical mechanisms can be work these objects: jet-base outflow solutions most natural explanations several cases; 5273 nucleus, presence an advection-dominated accretion flow consistent with luminosity upper limit.