Soon After the Birth of Radio Sources

Compact Symmetric Objects (CSOs) represent an early stage in the life of radio galaxies. Our kinematic studies over a 20 year timebase have unambiguously demonstrated that they expand fast and that the radio activity is recently born. The CSO evolution with time is however still a matter of investigation. If they are progenitors of the “classical double” radio sources, then in order to fit the the observed statistics of radio sources, CSOs must have decrease their luminosity and expansion speed with time. It is also possible that CSOs represent a phase of periodic activity of the central engine; in this case the presence of the old activity in the form of extended weak emission, should be observed.

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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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High-resolution VLA low radio frequency observations of the Perseus cluster: radio lobes, mini-halo, and bent-jet radio galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2003 ◽

2020 ◽

Vol 499 (4) ◽

pp. 5791-5805

Author(s):

M Gendron-Marsolais ◽

J Hlavacek-Larrondo ◽

R J van Weeren ◽

L Rudnick ◽

T E Clarke ◽

...

Keyword(s):

High Resolution ◽

Dynamic Range ◽

Galaxy Cluster ◽

High Dynamic Range ◽

Radio Galaxies ◽

Radio Sources ◽

Nearby Galaxy ◽

Cluster Galaxy ◽

Ngc 1275 ◽

Perseus Cluster

ABSTRACT We present the first high-resolution 230–470 MHz map of the Perseus cluster obtained with the Karl G. Jansky Very Large Array. The high dynamic range and resolution achieved have allowed the identification of previously unknown structures in this nearby galaxy cluster. New hints of sub-structures appear in the inner radio lobes of the brightest cluster galaxy NGC 1275. The spurs of radio emission extending into the outer X-ray cavities, inflated by past nuclear outbursts, are seen for the first time at these frequencies, consistent with spectral aging. Beyond NGC 1275, we also analyse complex radio sources harboured in the cluster. Two new distinct, narrowly collimated jets are visible in IC 310, consistent with a highly projected narrow-angle tail radio galaxy infalling into the cluster. We show how this is in agreement with its blazar-like behaviour, implying that blazars and bent-jet radio galaxies are not mutually exclusive. We report the presence of filamentary structures across the entire tail of NGC 1265, including two new pairs of long filaments in the faintest bent extension of the tail. Such filaments have been seen in other cluster radio sources such as relics and radio lobes, indicating that there may be a fundamental connection between all these radio structures. We resolve the very narrow and straight tail of CR 15 without indication of double jets, so that the interpretation of such head–tail sources is yet unclear. Finally, we note that only the brightest western parts of the mini-halo remain, near NGC 1272 and its bent double jets.

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Spatially resolved studies of extragalactic jets in high redshift radio galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315002239 ◽

2014 ◽

Vol 10 (S313) ◽

pp. 231-235

Author(s):

Leah K. Morabito ◽

Adam Deller ◽

J. B. R. Oonk ◽

Huub Röttgering ◽

George Miley

Keyword(s):

High Redshift ◽

Low Frequency ◽

Radio Galaxies ◽

Radio Sources ◽

Spatially Resolved ◽

Long Baseline ◽

Early Results ◽

Spectrum Radio ◽

Extragalactic Jets ◽

Frequency Survey

AbstractThe correlation between radio spectral steepness and redshift has been successfully used to find high redshift (z ⩾ 2) radio galaxies, but the origin of this relation is unknown. The ultra-steep spectra of high-z radio sources make them ideally suited for studies with the Low Band Antenna of the new Low Frequency Array, which covers 10–80 MHz and has baselines up to about 1300 km. As part of an ongoing survey, we use the longest baselines to map the low-frequency (< 70 MHz) spatial distributions along the jets of 5 bright extended steep spectrum high-z radio sources. From this, we will determine whether the spectra change over these spatially resolved sources, thereby constraining particle acceleration processes. We present early results from our low-frequency survey of ultra-steep spectrum radio galaxies. The first low frequency long baseline images of these objects are presented.

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A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). I. The Optical Counterparts of FIRST Radio Sources

The Astrophysical Journal ◽

10.3847/1538-4357/aae1ac ◽

2018 ◽

Vol 866 (2) ◽

pp. 140 ◽

Cited By ~ 2

Author(s):

Takuji Yamashita ◽

Tohru Nagao ◽

Masayuki Akiyama ◽

Wanqiu He ◽

Hiroyuki Ikeda ◽

...

Keyword(s):

Radio Galaxies ◽

Radio Sources ◽

Deep Exploration

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Fueling the central engine of radio galaxies

Astronomy and Astrophysics ◽

10.1051/0004-6361:20077599 ◽

2007 ◽

Vol 468 (3) ◽

pp. L71-L75 ◽

Cited By ~ 21

Author(s):

S. García-Burillo ◽

F. Combes ◽

R. Neri ◽

A. Fuente ◽

A. Usero ◽

...

Keyword(s):

Radio Galaxies ◽

Central Engine

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A Novel Method for Estimating the Ambient Medium Density Around Distant Radio Sources from Their Observed Radio Spectra

The Astrophysical Journal ◽

10.3847/1538-4357/ac116c ◽

2021 ◽

Vol 922 (2) ◽

pp. 197

Author(s):

Anna Wójtowicz ◽

Łukasz Stawarz ◽

Jerzy Machalski ◽

Luisa Ostorero

Keyword(s):

Radio Emission ◽

Ambient Medium ◽

Radio Galaxies ◽

Radiative Properties ◽

Radio Continuum ◽

Physical Parameters ◽

Radio Sources ◽

Data Set ◽

Radio Structure ◽

5 Ghz

Abstract The dynamical evolution and radiative properties of luminous radio galaxies and quasars of the FR II type, are well understood. As a result, through the use of detailed modeling of the observed radio emission of such sources, one can estimate various physical parameters of the systems, including the density of the ambient medium into which the radio structure evolves. This, however, requires rather comprehensive observational information, i.e., sampling the broadband radio continua of the targets at several frequencies, and imaging their radio structures with high resolution. Such observations are, on the other hand, not always available, especially for high-redshift objects. Here, we analyze the best-fit values of the source physical parameters, derived from extensive modeling of the largest currently available sample of FR II radio sources, for which good-quality multiwavelength radio flux measurements could be collected. In the analyzed data set, we notice a significant and nonobvious correlation between the spectral index of the nonthermal radio emission continuum, and density of the ambient medium. We derive the corresponding correlation parameters, and quantify the intrinsic scatter by means of Bayesian analysis. We propose that the discovered correlation could be used as a cosmological tool to estimate the density of ambient medium for large samples of distant radio galaxies. Our method does not require any detailed modeling of individual sources, and relies on limited observational information, namely, the slope of the radio continuum between the rest-frame frequencies 0.4 and 5 GHz, possibly combined with the total linear size of the radio structure.

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Compact Structure in Continuum Radio Sources

Australian Journal of Physics ◽

10.1071/ph910771 ◽

1991 ◽

Vol 44 (6) ◽

pp. 771

Author(s):

RT Schilizzi

Keyword(s):

Supernova Remnants ◽

Radio Galaxies ◽

Radio Sources ◽

Compact Structure ◽

Scale Structures ◽

Continuum Radio

Present-day VLBI networks make observations of compact structure in a wide variety of radio sources. Examples are shown of milli-arcsecond scale structures in radio galaxies, quasars, stars and supernova remnants.

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Tables of physical and morphological properties of nearby extended radio galaxies

Communications of the Byurakan Astrophysical Observatory ◽

10.52526/25792776-2021.68.1-75 ◽

2021 ◽

pp. 75-89

Author(s):

R. R. Andreasyan ◽

H. V. Abrahamyan

Keyword(s):

Radio Galaxies ◽

Elliptical Galaxies ◽

Morphological Data ◽

Morphological Properties ◽

Radio Sources ◽

Extragalactic Radio Sources ◽

Extended Radio

It is brought the physical and morphological data of 267 nearby radio galaxies identified with elliptical galaxies brighter than 18th magnitude (sample 1) and for 280 extragalactic radio sources with known position angles between the integrated intrinsic radio polarization and radio axes (sample 2).

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VLA observations of 20 FR II radio sources at 8.4 GHz

Astrophysics and Space Science ◽

10.1007/s10509-019-3654-5 ◽

2019 ◽

Vol 364 (10) ◽

Author(s):

Ilias Fernini

Keyword(s):

High Resolution ◽

Hot Spots ◽

Radio Galaxies ◽

Class Ii ◽

Outer Edge ◽

Radio Sources ◽

Large Sample ◽

Contour Maps ◽

Surrounding Environment

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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