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The Continuous Spectra of Radio Sources with Particular Reference to Non-Thermal Galactic Sources


Harris, Daniel Everett (1961) The Continuous Spectra of Radio Sources with Particular Reference to Non-Thermal Galactic Sources. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/N09S-3J04.


960 Mc observations of over 400 sources are reported in two parts. Part I contains position and intensity measurements of 106 sources (chiefly taken from the recent Cambridge surveys), and the results of 376 intensity measurements of sources previously observed at Sydney. Spectral indices are derived from the intensity measurements and the previous investigator's observations. The resulting spectral index distribution has a median value of -0.65 ± 0.10 and a dispersion such that 75% of the values lie within 0.25 of the median. Galactic sources show a larger dispersion of spectral index than do the sources assumed to be external galaxies.

Part II is based on 960 Mc observations of extended galactic nebulae, usually identified with supernova remnants. Contour diagrams of antenna temperature are presented for four of the larger objects. A detailed study of the Cygnus Loop shows that the radio emission is chiefly non-thermal, with a spectral index of -0.1 ± 0.1. An attempt to detect linear polarization places an upper limit of 30% for selected regions of the Cygnus Loop. Spectral indices ranging from -0.8 to +0.5 are derived for 12 other sources. Calculations show that the occurrence of optical synchrotron radiation is not ruled out by existing observations. An empirical relation between spectral index and physical size of supernova remnants suggests that the energy spectrum of relativistic particles flattens with age. A possible mechanism for this behavior is considered.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Astronomy and Physics) ; 3C radio sources; spectral index; Owens Valley Radio Observatory
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Astronomy
Minor Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Stanley, Gordon J. (advisor)
  • Bolton, John G. (advisor)
Group:Owens Valley Radio Observatory (OVRO), Astronomy Department
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1961
Non-Caltech Author Email:harris.d.e.42 (AT)
Additional Information:This was the first PhD thesis coming out of the Owens Valley Radio Observatory.
Record Number:CaltechETD:etd-03232006-111338
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1070
Deposited By: Imported from ETD-db
Deposited On:27 Mar 2006
Last Modified:17 Nov 2023 00:37

Thesis Files

PDF (Harris_de_1961.pdf) - Final Version
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