Variation in the Polarization Across Bends in the Spectra of Self-Absorbed Synchrotron Sources

1972 ◽  
Vol 2 (3) ◽  
pp. 140-142 ◽  
Author(s):  
D. B. Melrose
Keyword(s):  
Circular Polarization ◽  
Low Frequency ◽  
Radio Sources ◽  
Extragalactic Radio Sources

The accepted interpretation of the low frequency turnovers in the spectra of many extragalactic radio sources is that they are due to the effects of synchrotron self-absorption, i.e. to the source becoming optically thick. It has been shown that the signs of the degrees of both linear and circular polarization for a homogeneous source at frequencies where it is optically thick are opposite to those at frequencies where it is optically thin.

scholarly journals Results from a monitoring program of low frequency variable sources

1986 ◽  
Vol 119 ◽  
pp. 149-155
Author(s):  
L. Padrielli ◽  
R. Fanti ◽  
A. Ficarra ◽  
L. Gregorini ◽  
F. Mantovani
Keyword(s):  
Monitoring Program ◽  
Low Frequency ◽  
Radio Sources ◽  
Main Question ◽  
Extragalactic Radio Sources ◽  
Low Frequency Variability ◽  
Flux Variability

The flux variability of extragalactic radio sources at decimetric wavelengths (Low Frequency Variability LFV) is mostly associated with the nuclei of compact radio sources. But is a not yet well understood phenomenon. The main question still is: where does this phenomenon take place?

scholarly journals Spectral Index - Redshift Relation for Radio Galaxies and Quasars

1996 ◽  
Vol 175 ◽  
pp. 569-570
Author(s):  
R.D. Dagkesamanskii
Keyword(s):  
Flux Density ◽  
Spectral Index ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Cosmological Evolution ◽  
Radio Sources ◽  
Spectral Indices ◽  
Extragalactic Radio Sources

Cosmological evolution of synchrotron spectra of the powerful extragalactic radio sources was studied by many authors. Some indications of such an evolution had been found firstly by analysis of ‘spectral index - flux density’ (α – S) relation for the sample of relatively strong radio sources. Later Gopal-Krishna and Steppe extended the analysis to weaker sources and found that the slope of αmed(S) curve changes dramatically at intermediate flux densities. Gopal-Krishna and Steppe pointed out that the maxima of the αmed(S) curve and of differential source counts are at almost the same flux density ranges (see, Fig. 2). It has to be noticed that the all mentioned results were obtained using the low-frequency spectral indices and on the basis of low frequency samples.

scholarly journals Intensity Variations in Extragalactic Radio Sources at 13 cm

1972 ◽  
Vol 44 ◽  
pp. 224-224 ◽  
Author(s):  
G. D. Nicolson
Keyword(s):  
Low Frequency ◽  
Secular Change ◽  
Radio Sources ◽  
Complete Sample ◽  
Frequency Spectra ◽  
Extragalactic Radio Sources ◽  
The Relationship

Results of a three-year investigation into the variability of 55 Parkes sources at 13 cm are presented. Thirty-six of the sources comprise a complete sample of QSS with fluxes exceeding 2 flux units. The remaining sources include most other known or likely variables stronger than 2 flux units. The relationship between spectra and variability in QSS is investigated and it is confirmed that variables generally have flat low frequency spectra. A possible relationship between redshift and specific types of intensity variations is considered. Limits on the secular change in the intensity of non-variable QSS are set and are generally found to be ± 1.5% p.a. at 13 cm. Results for the remaining 19 sources are discussed and some preliminary findings of an extension patrol to include weaker sources in the range 1-2 flux units are given.

Low-frequency spectra of extragalactic radio sources

Astrophysics ◽  
1970 ◽  
Vol 4 (4) ◽  
pp. 252-255
Author(s):  
A. M. Aslanyan ◽  
V. G. Malumyan ◽  
V. A. Sanamyan
Keyword(s):  
Low Frequency ◽  
Radio Sources ◽  
Frequency Spectra ◽  
Extragalactic Radio Sources

The low-frequency spectra of a complete sample of extragalactic radio sources

1984 ◽  
Vol 89 ◽  
pp. 323 ◽  
Author(s):  
L. Gregorini ◽  
F. Mantovani ◽  
A. Eckart ◽  
P. Biermann ◽  
A. Witzel ◽  
...  
Keyword(s):  
Low Frequency ◽  
Radio Sources ◽  
Complete Sample ◽  
Frequency Spectra ◽  
Extragalactic Radio Sources
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