Jets of highly energized plasma with relativistic velocities are associated with black holes ranging in mass from a few times that of the Sun to the billion-solar-mass black holes at the centres of galaxies. A popular but unconfirmed hypothesis to explain how the plasma is energized is the 'internal shock model', in which the relativistic flow is unsteady. Faster components in the jet catch up to and collide with slower ones, leading to internal shocks that accelerate particles and generate magnetic fields. This mechanism can explain the variable, high-energy emission from a diverse set of objects, with the best indirect evidence being the unseen fast relativistic flow inferred to energize slower components in X-ray binary jets. Mapping of the kinematic profiles in resolved jets has revealed precessing and helical patterns in X-ray binaries, apparent superluminal motions, and the ejection of knots (bright components) from standing shocks in the jets of active galaxies. Observations revealing the structure and evolution of an internal shock in action have, however, remained elusive, hindering measurement of the physical parameters and ultimate efficiency of the mechanism. Here we report observations of a collision between two knots in the jet of nearby radio galaxy 3C 264. A bright knot with an apparent speed of (7.0 ± 0.8)c, where c is the speed of light in a vacuum, is in the incipient stages of a collision with a slower-moving knot of speed (1.8 ± 0.5)c just downstream, resulting in brightening of both knots--as seen in the most recent epoch of imaging.
Observational Evidence for the Accretion-Disk Origin for a Radio Jet in an Active GalaxyAP Marscher et al. Nature 417 (6889), 625-7. PMID 12050658.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 Ga …
A 300-parsec-long Jet-Inflated Bubble Around a Powerful Microquasar in the Galaxy NGC 7793MW Pakull et al. Nature 466 (7303), 209-12. PMID 20613836.Black-hole accretion states near or above the Eddington luminosity (the point at which radiation force outwards overcomes gravity) are still poorly known because of the r …
Large-scale, Decelerating, Relativistic X-Ray Jets From the Microquasar XTE J1550-564S Corbel et al. Science 298 (5591), 196-9. PMID 12364800.We have detected, at x-ray and radio wavelengths, large-scale moving jets from the microquasar XTE J1550-564. Plasma ejected from near the black hole traveled at relativi …
Jet Acceleration of the Fast Molecular Outflows in the Seyfert Galaxy IC 5063C Tadhunter et al. Nature 511 (7510), 440-3. PMID 25043049.Massive outflows driven by active galactic nuclei are widely recognized to have a key role in the evolution of galaxies, by heating the ambient gas, expelling it from the …
Jets, Hotspots and Lobes: What X-ray Observations Tell Us About Extra-Galactic Radio SourcesMJ Hardcastle. Philos Trans A Math Phys Eng Sci 363 (1837), 2711-27. PMID 16286286. - ReviewThe brightest and most numerous discrete radio sources in the sky, radio galaxies and quasars, are powered by twin jets of plasma which emerge at relativistic speeds from …
- Science. 2002 Sep 6;297(5587):1673-6 - PubMed