scholarly journals Depolarization of Extragalactic Radio Sources

1982 ◽  
Vol 97 ◽  
pp. 339-340
Author(s):  
M. Inoue ◽  
H. Tabara
Keyword(s):  
Faraday Rotation ◽  
Source Size ◽  
The Other ◽  
Radio Sources ◽  
Half Maximum ◽  
Radio Luminosity ◽  
Extragalactic Radio Sources ◽  
Other Hand ◽  
Percentage Polarization

In the last decade correlations of the depolarization parameter λd with several parameters, i.e., the radio luminosity L, redshift z, and source size D have been investigated by several authors, where λd is the wavelength at which the percentage polarization drops to its half maximum. Kronberg ET AL. (1972) first pointed out that λd decreases with increasing z, while Morris and Tabara (1973) showed that λd increases with L and suggested that the depolarization is due to the internal Faraday rotation within radio sources. Conway ET AL.(1974), on the other hand, suggested that the λd-(1+z) relation is primary. Recently, Cohen (1979) showed that the λd-z relation may be the remnant of the physically meaningful relation λd-L, though the former is statistically real.

scholarly journals Faraday Rotation Effect in Extragalactic Radio Sources

Nature ◽  
1963 ◽  
Vol 200 (4908) ◽  
pp. 765-765 ◽  
Author(s):  
A. G. PACHOLCZYK
Keyword(s):  
Faraday Rotation ◽  
Radio Sources ◽  
Rotation Effect ◽  
Extragalactic Radio Sources

scholarly journals Clustering of Galaxies about Extragalactic Radio Sources-Implications for Observations with the Einstein X-Ray Observatory

1980 ◽  
Vol 5 ◽  
pp. 723-726
Author(s):  
M. S. Longair ◽  
M. Seldner
Keyword(s):  
Correlation Function ◽  
Spectral Properties ◽  
Radio Sources ◽  
Radio Luminosity ◽  
X Ray ◽  
Extragalactic Radio Sources

The question which we have addressed is “what is the clustering of galaxies about extragalactic radio sources and how does it vary with the properties of the sources such as radio luminosity, optical spectral properties, radio morphology, etc”. Only a small fraction of strong radio sources belong to rich clusters and most of the work on weaker associations is of a somewhat subjective nature. Our approach has been to work with complete, statistically defined samples of bright radio sources and to cross-correlate the positions of the sources with the Lick counts of galaxies. In this approach, we never define exactly what we mean by a cluster as group of galaxies - clustering is simply defined as the amplitude of a correlation function. This approach is only possible because the Lick counts of galaxies have been studied in detail by Seldner et al. (1977) who calibrated the Lick counts over the whole of the sky.

scholarly journals On the Magnetic Fields of Galaxies

2021 ◽  
pp. 470-477
Author(s):  
R. R. Andreasyan
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Faraday Rotation ◽  
Radio Galaxies ◽  
Morphological Properties ◽  
Radio Sources ◽  
Extragalactic Radio Sources

We bring results of some our investigations of magnetic field of our Galaxy and extragalactic radio sources. For the study were used data of Faraday rotation of pulsars and extragalactic radio sources as well as data of physical and morphological properties of more than 500 radio galaxies of different morphological classes.

scholarly journals The Evolution of Linear Sizes

1982 ◽  
Vol 97 ◽  
pp. 401-410
Author(s):  
V. K. Kapahi ◽  
C. R. Subrahmanya
Keyword(s):  
Strong Correlation ◽  
Angular Size ◽  
Inverse Correlation ◽  
Radio Sources ◽  
Radio Luminosity ◽  
Complete Sample ◽  
Extragalactic Radio Sources ◽  
Rule Out

Possible evidence that the linear sizes of extragalactic radio sources were smaller at earlier epochs was first provided by the angular size redshift (θ-z) relation for double radio quasars (Legg 1970, Miley 1971, Wardle and Miley 1974). But because of the strong correlation between redshift (z) and radio luminosity (P) in flux limited radio samples, it is hard to decide if the observed decrease in sizes with z is caused by an epoch dependence of linear sizes (ℓ) or by an inverse correlation between P and ℓ. Several authors (eg. Stannard and Neal 1977, Wardle and Potash 1977, Hooley ET AL. 1978, Wills 1979, Masson 1980) have attempted to separate the two effects by comparing the properties of quasars from the 3CR survey with those from the 4C and Parkes samples. Although most of these studies appear to marginally favour a P-ℓ correlation, none of them can rule out even a fairly strong evolution in ℓ with z. Apart from the small numbers involved, the difficulty is that 3C and 4C quasars do not differ a great deal in their redshifts or luminosities. A complete sample of quasars at much weaker flux levels would be quite valuable in this regard.

scholarly journals A new look at the galactic magnetic field

1979 ◽  
Vol 84 ◽  
pp. 317-319
Author(s):  
P. P. Kronberg ◽  
M. Simard-Normandin
Keyword(s):  
Magnetic Field ◽  
Faraday Rotation ◽  
Linear Polarization ◽  
Radio Sources ◽  
Galactic Magnetic Field ◽  
Equal Area ◽  
Large Sample ◽  
Extragalactic Radio Sources ◽  
First Order ◽  
New Look

We have measured the linear polarization of a new large sample of extragalactic radio sources, and by combining these with polarization values already in the literature, we have been able to compute a large number of rotation measures, with improved quality. We have also investigated the depolarization properties of these sources and as a result have been able to identify most sources with a large internally generated Faraday rotation. Figure 1 shows the rotation measures of 475 extragalactic radio sources on an equal-area projection, after “cleaning out” the extragalactic effects to first order.

scholarly journals A bisymmetric spiral magnetic field in the Milky Way

1985 ◽  
Vol 106 ◽  
pp. 251-252
Author(s):  
Y. Sofue ◽  
M. Fujimoto
Keyword(s):  
Magnetic Field ◽  
Faraday Rotation ◽  
Large Scale ◽  
Milky Way ◽  
Radio Sources ◽  
Extragalactic Radio Sources ◽  
Large Scale Magnetic Field ◽  
Rotation Measure ◽  
The Galaxy ◽  
Field Lines

The distribution of Faraday rotation measure (RM) of extragalactic radio sources shows that a large-scale magnetic field in the Galaxy is oriented along the spiral arms. The field lines change direction from one arm to the next in the inter-arm region.

Polarization of extragalactic radio sources: CMB foregrounds and telescope calibration issues

2016 ◽  
Vol 25 (11) ◽  
pp. 1640009 ◽  
Author(s):  
Marcella Massardi ◽  
Vincenzo Galluzzi ◽  
Rosita Paladino ◽  
Carlo Burigana
Keyword(s):  
Cosmic Microwave Background ◽  
Radio Source ◽  
High Redshift ◽  
The Other ◽  
Radio Sources ◽  
Polarization Rotation ◽  
Microwave Background ◽  
Extragalactic Radio Sources ◽  
Systematic Effects ◽  
The One

Radio source observations play important roles in polarimetric cosmological studies. On the one hand, they constitute the main foregrounds for cosmic microwave background (CMB) radiation on scales smaller than 30 arcmin up to 100 GHz, on the other they can be used as targets for validation of products of polarimetric experiments dedicated to cosmology. Furthermore, extragalactic high-redshift sources have been used for cosmic polarization rotation (CPR) investigation. In this paper, we will discuss the support to cosmological studies from ground-based polarimetric observations in the radio and millimetric wavelength bands. Most of the limits to accuracy improvements arise from systematic effects and low calibration quality. We will discuss some details of interferometric calibration procedures and show some of the perspectives that the Atacama large millimeter array (ALMA) could offer for CPR studies.

scholarly journals Extragalactic Radio Sources: Jet/Lobe Internal Pressure and Consequences

2021 ◽  
pp. 20-25
Author(s):  
Ezeugo Jeremiah Chukwuemerie
Keyword(s):  
Internal Pressure ◽  
Analytical Methods ◽  
Ambient Medium ◽  
Source Size ◽  
Central Core ◽  
Radio Sources ◽  
Medium Density ◽  
Host Galaxies ◽  
Extragalactic Radio Sources

In this work, we use analytical methods to describe expansion of Extragalactic Radio Sources (EGRS). Result shows that source size expansion depends on the following parameters: age of the source, lobe internal pressure, ambient medium density, and angle of observation. Moreover, from the analyses, we have shown that the obtained results, and , suggestively implies that  and . This shows that since , jet internal pressure exceeds the lobe’s internal pressure. Therefore, for a typical EGRS, this simply indicates that ambient medium density is higher in the jet region than in the region of the lobe. This is expected since the ambient density thins out from the central core to the region where lobe is located. It is in consonance with the notion that for large extended EGRS, lobes are located outside the host galaxies rather than within the host galaxies. Moreover, we can conclude from these results that compact steep spectrum sources have denser ambient medium than their more extended counterparts.

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