Observational evidence for the accretion-disk origin for a radio jet in an active galaxy

DOI: 
10.1038/nature00772
Publication date: 
06/06/2002
Main author: 
Marscher, AP
IAA authors: 
Gomez, JL
Authors: 
Marscher, AP; Jorstad, SG; Gomez, JL; Aller, MF; Terasranta, H; Lister, ML; Stirling, AM
Journal: 
NATURE
Publication type: 
Article
Volume: 
417
Pages: 
625-627
Number: 
Abstract: 
Accretion of gas onto black holes is thought to power the relativistic jets of material ejected from active galactic nuclei (AGN) and the 'microquasars' located in our Galaxy(1-3). In microquasars, superluminal radio-emitting features appear and propagate along the jet shortly after sudden decreases in the Xray fluxes(1). This establishes a direct observational link between the black hole and the jet: the X-ray dip is probably caused by the disappearance of a section of the inner accretion disk(4) as it falls past the event horizon, while the remainder of the disk section is ejected into the jet, creating the appearance of a superluminal bright spot(5). No such connection has hitherto been established for AGN, because of insufficient multi-frequency data. Here we report the results of three years of monitoring the X-ray and radio emission of the galaxy 3C120. As has been observed for microquasars, we find that dips in the X-ray emission are followed by ejections of bright superluminal knots in the radio jet. The mean time between X-ray dips appears to scale roughly with the mass of the black hole, although there are at present only a few data points.
Database: 
WOK
Keywords: