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Studies of compact extragalactic radio sources

Citation

Linfield, Roger Paul (1981) Studies of compact extragalactic radio sources. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-09022008-153247

Abstract

Three studies of compact, extragalactic radio sources are presented.

In the first, VLBI maps are presented of the nuclear cores of four radio galaxies which have large symmetric radio lobes: 3C 111, 3C 390.3, Cyg A, and 0055+30. Each source contains a nuclear jet having a scale of 1 pc, but no counterjets are seen. The jets in 3C 111 and 0055+30 point directly at the outer radio lobes, but in 3C 390.3 and Cyg A the jets are pointed from 4 to 6 degrees away from the lobes.

The implications of the maps and models of these sources are considered in the second study. It is concluded that in all four cases, the observed asymmetry reflects an intrinsic asymmetry on a msec scale. The minimum pressure in the four jets is calculated, and it is concluded that the jet in Cyg A is very unlikely to be confined by gas pressure.

In the third study, an attempt is made to explain the structure of compact radio sources with a precession-like motion or a relativistic jet. It is found that the curvature of these sources can be readily explained in this way. In addition, the knots which are often revealed by VLBI observations arise naturally in such a model. The main problem with the model is that it cannot by itself explain the arcsecond structure of asymmetric radio sources.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Astronomy
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Cohen, Marshall H.
Thesis Committee:
  • Unknown, Unknown
Defense Date:28 April 1981
Record Number:CaltechETD:etd-09022008-153247
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-09022008-153247
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3317
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:10 Sep 2008
Last Modified:26 Dec 2012 02:59

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