Relativistic jets and beams in radio galaxies
Abstract
RADIO-ASTRONOMICAL observations have recently clarified the link between the components of extended double sources and the primary power supply in the central galactic nucleus. The new data vindicate the general idea1-4 that power is continuously supplied by beams; it seems, furthermore, that the beams are collimated in a scale little larger than the central power supply (<< 1 pc), and that the orientation remains fairly steady over the whole lifetime. The giant double source 3C236, 2 × 107 light yr in total extent5,6, has a compact central component aligned with the overall axis7; a similar phenomenon is observed in Cygnus A (ref. 8). In NGC6251, a straight jet 200 kpc long9 emanates from a `blowtorch' <~ 0.1 pc wide in the galactic nucleus10. There is a radio jet11 in 3C147 reminiscent of the well-known features in M87 and 3C273; and very long baseline interferometry (VLBI) reveals linear structure in several compact extragalactic sources12. It is argued here that collimation occurs close to a central collapsed object, and that the beams are orientated along its spin axis. Strong-field gravitational effects then stabilise the beams against jitter even if the gas fuelling the source has an inconstant flow pattern. Radio galaxies where the beam axis seems to have gradually drifted or swung, rather than pointing in a constant direction, may belong to a special class that have experienced collisions and recurrent nuclear activity.
- Publication:
-
Nature
- Pub Date:
- October 1978
- DOI:
- 10.1038/275516a0
- Bibcode:
- 1978Natur.275..516R
- Keywords:
-
- Beams (Radiation);
- Cosmic Plasma;
- Galactic Nuclei;
- Plasma Jets;
- Radio Galaxies;
- Relativistic Plasmas;
- Relativistic Velocity;
- Black Holes (Astronomy);
- Collimation;
- Nuclear Reactions;
- Radio Sources (Astronomy);
- Astrophysics