Complex Radio Structure Research Articles

Is a bi-stable beam responsible for the complex radio structure of 3C133?

It is generally assumed that the extended lobes of radio emission found in many extragalactic sources are powered by oppositely directed supply beams of relativistic particles emanating from the central galactic nucleus1,2. The complexity and asymmetry of the structure in many sources has, however, led to speculation of a ‘flip-flop’ beam mechanism3,4 where energy is supplied alternately to each radio lobe. Recent high resolution observations of the radio structure of 3C133 reveal a complex structure in which rotation of the source axis may have uncovered evidence for such a bi-stable nature of the energy supply. There are, however, several difficulties in such an interpretation.

The Double Quasar 0957+561: A Radio Study at 6-Centimeters Wavelength

The optical double quasar 0957+561 has been interpreted as the gravitational double image of a single object. A radio map made with the Very Large Array of the National Radio Astronomy Observatory shows unresolved sources coincident With the optical images as well as a complex of related extended emission. Although the results cannot rule out the gravitational lens hypothesis, the complex radio structure is more easily interpreted as two separate quasars. The optical and radio properties of the two quasars are so similar that the two must have been formed at the same time with similar initial conditions.

Radio structure of the M87 jet

THE central region of M87 has a complex radio structure. There are at least three components1,2, with diameters ≈0″.0013, ≈0″.01 and ≈0″.3, coincident with the optical nucleus of the galaxy and on either side there are two elongated components, ≈25″ in extent, the radio counterparts of the jet and counterjet3,4. When observed with a resolution of ≈5″, the structure of these outer components is similar and depends little on observing frequency, but at higher resolutions the jet component is seen to possess fine structure which the other lacks5,6. Here I report results of interferometer observations at 408 and 1,666 MHz, with resolving powers ≈0.5″ along the jet, which reveal the position and extent of this fine structure in more detail.

Lunar-occultation studies of 4C radio sources at 327 MHz

view Abstract Citations (30) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Lunar-occultation studies of 4C radio sources at 327 MHz Kapahi, V. K. ; Joshi, M. N. ; Subrahmanya, C. R. ; Gopal-Krishna Abstract Lunar-occultation observations made with the Ooty radio telescope have been used to derive accurate radio positions and brightness distributions for 27 radio sources from the 4C catalog, in the flux density range of about 14 f.u. at 327 MHz. Most of the sources appear resolved and show the typical double or more complex radio structure. The observed total angular extent of the sources suggests that statistically the 4C sources are at greater distances as compared to the 3C sources. Twelve of the 27 sources are optically identified. The optical positions of objects identified or close to the radio positions have been estimated to an rms accuracy of j 0.5 arcsec in each coordinate in most cases. Publication: The Astronomical Journal Pub Date: October 1973 DOI: 10.1086/111472 Bibcode: 1973AJ.....78..673K full text sources ADS | data products SIMBAD (28)

Quasars as protoclusters of galaxies

A hypothesis is put forward according to which dense bodies (QSG), which occasionally transform into quasars, decay into components and their subsequent fragmentation results in the formation of groups and clusters of galaxies. Recurrent nonthermal radio emission continues during all the subsequent stages of fragmentation and evolution of the QSG's, and the fraction of nonthermal optical emission decreases. This hypothesis explains the absence of quasars from clusters of galaxies, their complex radio structure, the structural details of clusters, and the distribution of radio galaxies in them. The gravitational redshift component becomes appreciable and the requirements imposed on the energy output per unit mass of the quasars become less demanding. This hypothesis puts into concrete terms Ambartsumyan's idea about the cascade fragmentation of dense material and the dispersion of fragments in the form of disintegrating stellar systems.