Optical Polarization and Imaging of Hot Spots in Radio Galaxies

Abstract We report the last observational paper of hot spots for 20 Fanaroff-Riley class II (FR II) sources. These sources are part of a large sample of 98 FR II to study the unification scheme of FR II radio galaxies (RGs) and quasars (QSRs) using the hotspots (HSs) location and morphology. High-resolution VLA observations at 8.4 GHz were conducted for the whole sample. The investigation of HSs properties in FR II radio sources is essential for a better understanding of the dynamics related to the objects and their impact on the surrounding environment. HSs were classified into edged and recessed types, where the former is located at a radio lobe’s outer edge, and the latter is embedded within the lobe. The present sub-sample contains 12 RGs and 8 QSRs. Radio contour maps for each source were presented using the VLA in its A and B configurations. In total, we have identified 18 HSs for these 20 radio sources. The 12 RGs possess 8 edged HSs and 2 recessed HSs. The 8 QSRs possess 6 edged HSs and 2 recessed HSs. Out of the 14 edged HSs, RGs and QSRs possess $\sim57\%$∼57% and $\sim43\%$∼43%, respectively. A thorough morphological discussion of the 20 sources with their HSs is presented in the present work.

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The optical polarization of the low-redshift radio galaxies 3CR 33, 305, 321 and 459

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/262.4.1029 ◽

1993 ◽

Vol 262 (4) ◽

pp. 1029-1036 ◽

Cited By ~ 23

Author(s):

P. W. Draper ◽

S. M. Scarrott ◽

C. N. Tadhunter

Keyword(s):

Radio Galaxies ◽

Optical Polarization

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Large Scale Emission from Radio Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900027170 ◽

1982 ◽

Vol 97 ◽

pp. 13-20

Author(s):

H. Andernach ◽

R. Wielebinski

Keyword(s):

Total Energy ◽

Internal Energy ◽

Hot Spots ◽

Large Scale ◽

Energy Content ◽

Radio Galaxies ◽

Emission Region ◽

Diffuse Emission ◽

Transfer Energy ◽

Break Up

Radio galaxies are known to exhibit a variety of scales in their structure. First we have the nuclear sources, which so far have not been completely resolved even on the scale of 1/10 milliarcsecond with VLBI observing methods (e.g. Preuss, 1981). Then we have the ‘jets’ (which at some stage break up into ‘blobs’) which are considered to transfer energy from the ‘nuclear engine’ to the outer heads. The latter appear to be the sites of transfer of the collimated jet energy into a diffuse emission region. Despite their usually low brightness these diffuse emission regions dominate the internal energy content in particles and fields, even for the collimated doubles. Note that only 1% of the total energy in Cyg A is in the hot spots (Perola, 1981).

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Bent Jets in Radio Quasars

Symposium - International Astronomical Union ◽

10.1017/s0074180900027546 ◽

1982 ◽

Vol 97 ◽

pp. 137-138

Author(s):

Susan G. Neff

Keyword(s):

Hot Spots ◽

Radio Galaxies ◽

Plasma Instability ◽

Radio Sources ◽

Central Engine ◽

Central Nozzle ◽

Quasars And Radio Galaxies

How is energy transported out from the central engine in quasars and radio galaxies to the distant radio lobes? This problem has been around since the early discovery of classical double radio sources, and is still not answered in detail. The idea of relativistic beams was first suggested by Martin Rees as a means of transporting plasma out of the nucleus (Rees, 1971, Blandford and Rees, 1974). This idea gained support first from the discovery of hot spots in the radio lobes of these large classical double sources, and later by observations of the beams themselves in radio galaxies. As more jets were observed, it became obvious that they were often curved, serpentine, or even sharply bent. This behavior has been modeled as precession of the central nozzle (Bridle et al., 1976, Ekers et al., 1978), as nuclear refraction (Henriksen et al., 1981), as a growing plasma instability (Hardee, 1981) and as various combinations of the above. At the present time, it seems safest to conclude that there are some examples of each of these processes known.

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Relativistic and Slowing Down: The Flow in the Hot Spots of Powerful Radio Galaxies and Quasars

The Astrophysical Journal ◽

10.1086/375796 ◽

2003 ◽

Vol 589 (1) ◽

pp. L5-L8 ◽

Cited By ~ 73

Author(s):

Markos Georganopoulos ◽

Demosthenes Kazanas

Keyword(s):

Hot Spots ◽

Radio Galaxies ◽

Powerful Radio ◽

Slowing Down

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Optical polarization in distant radio galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/264.2.421 ◽

1993 ◽

Vol 264 (2) ◽

pp. 421-438 ◽

Cited By ~ 70

Author(s):

Andrea Cimatti ◽

Sperello di Serego Alighieri ◽

Robert A. E. Fosbury ◽

Marco Salvati ◽

Duncan Taylor

Keyword(s):

Radio Galaxies ◽

Optical Polarization

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Viewing Classical Radio Galaxies with the Upgraded GMRT and MeerKAT—A Progress Report

Galaxies ◽

10.3390/galaxies9040087 ◽

2021 ◽

Vol 9 (4) ◽

pp. 87

Author(s):

Dharam V. Lal ◽

Portia Legodi ◽

Bernie Fanaroff ◽

Tiziana Venturi ◽

Oleg M. Smirnov ◽

...

Keyword(s):

Radio Emission ◽

Hot Spots ◽

Classification Scheme ◽

Local Environment ◽

Radio Galaxies ◽

Progress Report ◽

Filamentary Structure ◽

Current Classification ◽

The Rich ◽

Automated Procedures

We present a progress report of a study of FR I and FR II radio galaxies. Several new morphological features in the radio emission are now revealed using the high (μJy) sensitivity reached in the range 550–1712 MHz, more than a factor of three, at the high (∼4″−7″) angular resolution with the upgraded Giant Metrewave Radio Telescope (uGMRT) and MeerKAT. Therefore, the aim of this study is to understand if we need to revise our current classification scheme for classical radio galaxies. In order to address our goals, we have carefully constructed a sample of 14 (6 FR I, 6 FR II and 2 FR 0) radio galaxies. The uGMRT and MeerKAT images of our four target sources revealed a wealth of morphological details, e.g., filamentary structure in the emission from the lobes, misalignments, radio emission beyond the hot-spots in three sources, etc.; see Fanaroff et al. (2021). Here, we present preliminary results for two more radio galaxies from our sample using uGMRT, in the light of the local environment. Finally, we are awaiting uGMRT and MeerKAT observations of remaining sample sources. Our results show that for the radio galaxies in this study, the morphological classification scheme for the classical FR I/FR II radio galaxies still holds, even with the improved imaging capabilities of the uGMRT and MeerKAT. Furthermore, we need to be cautious when using automated procedures for classification schemes, e.g., in surveys (with poorer sensitivities and angular resolutions) because of the rich morphological details that are shown in our uGMRT and MeerKAT images.

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