Some Features in the Spectra of Extragalactic Radio Sources

1981 ◽  
Vol 4 (2) ◽  
pp. 184-187 ◽  
Author(s):  
O. B. Slee
Keyword(s):  
Spectral Index ◽  
Recent Analysis ◽  
Radio Sources ◽  
Usual Definition ◽  
Extragalactic Radio Sources ◽  
Flux Data ◽  
Straight Line ◽  
Consistent Manner ◽  
Definition Of ◽  
Second Degree

A recent analysis of the spectra of about 2000 sources in the Culgoora-3 list (Slee 1977) of radio sources (Slee et al. 1981) has revealed some interesting features which may be the result of source evolution. The Culgoora-3 spectra were obtained by combining the 80 and 160 MHz flux densities from the Culgoora radioheliograph with other published flux data between 10 and 10,000 MHz; this is probably the most accurate set of spectra yet derived for a large number of sources selected for observation in a reasonably consistent manner. In addition to fitting the log S-log v data for each source with a straight line (its slope is the usual definition of spectral index) Slee et al. also fitted second-degree and third-degree polynomials to search for curvature in the spectra.

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 The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources (III)

2020 ◽  
Vol 20 (2) ◽  
pp. 025 ◽  
Author(s):  
Zhi-Yuan Pei ◽  
Jun-Hui Fan ◽  
Denis Bastieri ◽  
Jiang-He Yang ◽  
Hu-Bing Xiao ◽  
...  
Keyword(s):  
Spectral Index ◽  
Radio Sources ◽  
Extragalactic Radio Sources ◽  
The Relationship

scholarly journals Comparison of Radio and Optical Polarization in Extended Extragalactic Radio Sources: I. Observations

1990 ◽  
Vol 140 ◽  
pp. 449-450
Author(s):  
H.-J. Röser ◽  
K. Meisenheimer
Keyword(s):  
Spectral Index ◽  
Hot Spots ◽  
Near Infrared ◽  
Detailed Comparison ◽  
Radio Sources ◽  
Optical Polarization ◽  
Extragalactic Radio Sources ◽  
Flux Measurements ◽  
Synchrotron Light ◽  
Infrared Frequencies

We presented new observations in various wavebands of those extragalactic radio sources for which the emission of optical synchrotron light is established by polarimetric investigations (jets of M 87 and 3C 273, hot spots in the lobes of 3C 20, 3C 33 and Pictor A). In addition to optical spectral index and polarization maps, we collected flux measurements at radio, millimetre, and near-infrared frequencies. Our observations result in accurate synchrotron spectra between 109 and 1015 Hz. For some sources a detailed comparison between radio and optical polarization is possible.

Spectral Index Studies of Extragalactic Radio Sources

1977 ◽  
pp. 99-106
Author(s):  
P. Katgert ◽  
L. Padrielli ◽  
J. K. Katgert ◽  
A. G. Willis
Keyword(s):  
Spectral Index ◽  
Radio Sources ◽  
Extragalactic Radio Sources

scholarly journals The Caltech-Jodrell Bank VLBI Surveys

1998 ◽  
Vol 164 ◽  
pp. 17-24
Author(s):  
T.J. Pearson ◽  
I.W.A. Browne ◽  
D.R. Henstock ◽  
A.G. Polatidis ◽  
A.C.S. Readhead ◽  
...  
Keyword(s):  
Flux Density ◽  
Angular Size ◽  
Optical Observations ◽  
Radio Sources ◽  
Limited Sample ◽  
Extragalactic Radio Sources ◽  
Superluminal Motion ◽  
Definition Of ◽  
5 Ghz

AbstractThe Caltech-Jodrell Bank VLBI surveys of bright extragalactic radio sources north of declination 35° were carried out between 1990 and 1995 using the Mark-II system, achieving images with a resolution of about 1 mas at 5 GHz. The CJl survey (together with the older “PR” survey) includes 200 objects with 5 GHz flux density greater than 0.7 Jy; the CJ2 survey includes 193 flat-spectrum sources with 5 GHz flux density greater than 0.35 Jy; and we have defined a complete flux-density limited sample, CJF, of 293 flat-spectrum sources stronger than 0.35 Jy. We summarize the definition of the samples and the VLBI, VLA, MERLIN, and optical observations, and present some highlights of the astrophysical results. These include: (1) superluminal motion and cosmology; (2) morphology and evolution of the “compact symmetric objects” (CSOs); (3) two-sided motion in some CSOs; (4) the angular-size-redshift diagram; (5) misalignment of parsec-scale and kiloparsec-scale jets.

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