scholarly journals The Extraordinary Radio Galaxy MRC B1221–423

2003 ◽  
Vol 20 (1) ◽  
pp. 1-5 ◽  
Author(s):  
V. Safouris ◽  
R. W. Hunstead ◽  
O. R. Prouton
Keyword(s):  
Radio Source ◽  
Radio Galaxy ◽  
Early Stage ◽  
Elliptical Galaxy ◽  
Empirical Relationship ◽  
Host Galaxy ◽  
Narrow Line ◽  
Powerful Radio ◽  
Double Structure ◽  
The Core

AbstractMRC B1221–423 is a compact steep spectrum (CSS) radio source in the core of a remarkable elliptical galaxy. We examine its environment with long-slit spectra and multicolour images. A high-resolution synthesis image shows the radio source to have a 1″.5 (5.7 kpc) double structure. We use the empirical relationship between jet kinetic power and narrow line luminosity to infer a source age of ˜105 yr. The z = 0.1706 host galaxy is clearly disturbed, with tidal features and shells providing plausible evidence for a merger with one or more close companions. This evidence leads us to conclude that B1221–423 may be the progenitor of a much larger source, caught at an early stage in its radio evolution. We speculate that it is the interaction and accompanying events which have triggered this young powerful radio source.

scholarly journals 3C236 - The Giant Radio Galaxy with a Compact Steep Spectrum Nucleus and a Compact Two-Sided Jet

1988 ◽  
Vol 129 ◽  
pp. 127-128
Author(s):  
R. T. Schilizzi ◽  
E. D. Skillman ◽  
G. K. Miley ◽  
P. D. Barthel ◽  
J. M. Benson ◽  
...  
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
Radio Galaxy ◽  
Elliptical Galaxy ◽  
Double Structure

3C236 is the largest radio source known. It has a 39 arcmin double structure (3.0 Mpc, Ho=75 kms−1 Mpc−1) in which the SE lobe is narrow and edge-brightened and the NW lobe more diffuse and centre-brightened (Barthel et al., 1985). About half the flux density comes from a steep spectrum (α = −0.7) radio core of overall size 1.3 arcsec (2.2 kpc) located in the centre of a 17m elliptical galaxy with redshift 0.0988.

The compact radio source 2021 + 614 - A peculiar narrow-line radio galaxy

1984 ◽  
Vol 279 ◽  
pp. 112 ◽  
Author(s):  
N. Bartel ◽  
I. I. Shapiro ◽  
J. P. Huchra ◽  
H. Kuhr
Keyword(s):  
Radio Source ◽  
Radio Galaxy ◽  
Narrow Line ◽  
Compact Radio Source

scholarly journals Properties of Radio Source Host Galaxies

2003 ◽  
Vol 20 (1) ◽  
pp. 6-11 ◽  
Author(s):  
Wim de Vries
Keyword(s):  
Radio Source ◽  
Large Scale ◽  
Radio Galaxy ◽  
Host Galaxy ◽  
Host Galaxies ◽  
State Of Affairs

AbstractA brief overview of the current radio source host galaxy state of affairs is given. All the evidence appears to point towards a scenario in which the young radio source expands through the host galaxy on timescales of 105–106 yr, before it ends its life as a large scale FR II radio galaxy. The place and role of the quasars in this evolutionary picture is unclear, however, and remains an issue of debate.

scholarly journals Hydrodynamical backflow in X-shaped radio galaxy PKS 2014−55

2020 ◽  
Vol 495 (1) ◽  
pp. 1271-1283 ◽  
Author(s):  
W D Cotton ◽  
K Thorat ◽  
J J Condon ◽  
B S Frank ◽  
G I G Józsa ◽  
...  
Keyword(s):  
Radio Source ◽  
Radio Galaxy ◽  
Angular Resolution ◽  
Position Angle ◽  
Host Galaxy ◽  
Field Orientation ◽  
Hot Gas ◽  
Bright Region ◽  
Projected Length ◽  
The Magnetic Field

ABSTRACT We present MeerKAT 1.28 GHz total-intensity, polarization, and spectral-index images covering the giant (projected length l ≈ 1.57 Mpc) X-shaped radio source PKS 2014−55 with an unprecedented combination of brightness sensitivity and angular resolution. They show the clear ‘double boomerang’ morphology of hydrodynamical backflows from the straight main jets deflected by the large and oblique hot-gas halo of the host galaxy PGC 064440. The magnetic field orientation in PKS 2014−55 follows the flow lines from the jets through the secondary wings. The radio source is embedded in faint ($T_\mathrm{b} \approx 0.5 \mathrm{\, K}$) cocoons having the uniform brightness temperature and sharp outer edges characteristic of subsonic expansion into the ambient intragroup medium. The position angle of the much smaller (l ∼ 25 kpc) restarted central source is within 5° of the main jets, ruling out models that invoke jet re-orientation or two independent jets. Compression and turbulence in the backflows probably produce the irregular and low polarization bright region behind the apex of each boomerang as well as several features in the flow with bright heads and dark tails.

scholarly journals Radio Galaxy Zoo: machine learning for radio source host galaxy cross-identification

2018 ◽  
Vol 478 (4) ◽  
pp. 5547-5563 ◽  
Author(s):  
M J Alger ◽  
J K Banfield ◽  
C S Ong ◽  
L Rudnick ◽  
O I Wong ◽  
...  
Keyword(s):  
Machine Learning ◽  
Radio Source ◽  
Radio Galaxy ◽  
Host Galaxy

scholarly journals PKS 2250–351: A giant radio galaxy in Abell 3936

2020 ◽  
Vol 37 ◽  
Author(s):  
N. Seymour ◽  
M. Huynh ◽  
S. S. Shabala ◽  
J. Rogers ◽  
L. J. M. Davies ◽  
...  
Keyword(s):  
Radio Galaxy ◽  
Elliptical Galaxy ◽  
Host Galaxy ◽  
The Galaxy ◽  
Order Of Magnitude ◽  
Mass Assembly ◽  
Murchison Widefield Array ◽  
Ir Emission ◽  
Jet Power ◽  
Compact Array

Abstract We present a detailed analysis of the radio galaxy PKS $2250{-}351$ , a giant of 1.2 Mpc projected size, its host galaxy, and its environment. We use radio data from the Murchison Widefield Array, the upgraded Giant Metre-wavelength Radio Telescope, the Australian Square Kilometre Array Pathfinder, and the Australia Telescope Compact Array to model the jet power and age. Optical and IR data come from the Galaxy And Mass Assembly (GAMA) survey and provide information on the host galaxy and environment. GAMA spectroscopy confirms that PKS $2250{-}351$ lies at $z=0.2115$ in the irregular, and likely unrelaxed, cluster Abell 3936. We find its host is a massive, ‘red and dead’ elliptical galaxy with negligible star formation but with a highly obscured active galactic nucleus dominating the mid-IR emission. Assuming it lies on the local M– $\sigma$ relation, it has an Eddington accretion rate of $\lambda_{\rm EDD}\sim 0.014$ . We find that the lobe-derived jet power (a time-averaged measure) is an order of magnitude greater than the hotspot-derived jet power (an instantaneous measure). We propose that over the lifetime of the observed radio emission ( ${\sim} 300\,$ Myr), the accretion has switched from an inefficient advection-dominated mode to a thin disc efficient mode, consistent with the decrease in jet power. We also suggest that the asymmetric radio morphology is due to its environment, with the host of PKS $2250{-}351$ lying to the west of the densest concentration of galaxies in Abell 3936.

scholarly journals Discovery of a new extragalactic circular radio source with ASKAP: ORC J0102–2450

2021 ◽  
Author(s):  
Bärbel S Koribalski ◽  
Ray P Norris ◽  
Heinz Andernach ◽  
Lawrence Rudnick ◽  
Stanislav Shabala ◽  
...  
Keyword(s):  
Radio Source ◽  
Blast Wave ◽  
Radio Galaxy ◽  
Elliptical Galaxy ◽  
Circular Ring ◽  
The South ◽  
Square Kilometre Array ◽  
South Eastern ◽  
Companion Galaxy

Abstract We present the discovery of another Odd Radio Circle (ORC) with the Australian Square Kilometre Array Pathfinder (ASKAP) at 944 MHz. The observed radio ring, ORC J0102–2450, has a diameter of ∼70 arcsec or 300 kpc, if associated with the central elliptical galaxy DES J010224.33–245039.5 (z ∼ 0.27). Considering the overall radio morphology (circular ring and core) and lack of ring emission at non-radio wavelengths, we investigate if ORC J0102–2450 could be the relic lobe of a giant radio galaxy seen end-on or the result of a giant blast wave. We also explore possible interaction scenarios, for example, with the companion galaxy, DES J010226.15–245104.9, located in or projected onto the south-eastern part of the ring. We encourage the search for further ORCs in radio surveys to study their properties and origin.

Projection Effects and Radio Source Morphology

1980 ◽  
Vol 4 (1) ◽  
pp. 74-76 ◽  
Author(s):  
J. E. Reynolds
Keyword(s):  
Radio Source ◽  
Physical Theory ◽  
Radio Galaxy ◽  
Computer Code ◽  
Line Of Sight ◽  
Clusters Of Galaxies ◽  
Diverse Range ◽  
Double Structure ◽  
Hot Plasma ◽  
Tail Shape

Since the discovery of the first ‘head-tail’ radio source (Ryle and Windram, 1968) extensive radio surveys of clusters of galaxies have revealed a surprisingly diverse range of source morphology. In additions to the familiar symmetric double-lobed shape, several other morphological types are now recognised; these are presumed to be due to interaction between the source and a relatively dense, hot plasma pervading rich clusters. In particular, rapid motion of a radio galaxy with respect to this inter-galactic medium appears to produce a ‘bent-double’ shape, or in more severe cases, a ‘double-tail’ or ‘head-tail’ shape. In such cases, the source no longer has the simple symmetry of ‘ordinary’ double structure and it is clear that the attitude of the source with respect to the line of sight may markedly affect what is observed. Results and details are given below of a simple computer code used to simulate the appearance of a hypothetical bent-double source seen in projection. It is emphasised that the model has been chosen as one that can represent in a simple way many of the observed morphological forms and is not based on any physical theory of radiation or emission processes.

scholarly journals Different Types of Radio Sources and Possible Evolution of Radio Galaxies

2002 ◽  
Vol 184 ◽  
pp. 301-303
Author(s):  
Gabriel A. Ohanian
Keyword(s):  
Radio Source ◽  
Large Scale ◽  
Large Range ◽  
Host Galaxy ◽  
Radio Sources ◽  
Powerful Radio ◽  
Host Galaxies ◽  
Radio Structure ◽  
Different Types ◽  
The Universe

Extragalactic radio sources have been studied for many years, but it is still unclear how they are formed and evolve. The sizes of the most powerful radio emitters in the Universe vary from less than one parsec to more than 1 Mpc. This large range of sizes has been interpreted as evidence for the evolution of the linear sizes of radio structure (e.g., O’Dea and Baum, 1997). A crucial element in the study of their evolution is the identification of the young compact counterparts of “old” FRI/FRII extended objects. Good candidates for young radio sources are those with peaked spectra (Gigahertz Peaked Spectrum - GPS and Compact Steep Spectrum - CSS, e.g., O’Dea 1998). Radio sources are presumably born in the very compact GPS phase, then they expand beyond 1 kpc into the CSS regime and finally, they reach a size of 20 kpc, and afterwards evolve into large-scale radio sources (young scenario, e.g., O’Dea 1998). Alternatively, GPS sources may be compact because a particularly dense environment prevents them from growing larger (old scenario, e.g., O’Dea 1998). In either scenario, the radio source host galaxy determines the time evolution of the radio structure. By studying the optical environments and host galaxies we hope to obtain clues to the evolution of the radio sources. Similarities or differences in host galaxy properties over a range of radio source types and sizes enable us to investigate possible differences or similarities of the radio size class as a whole.

scholarly journals 1245+676 — A CSO/GPS Source being an Extreme Case of a Double-Double Structure

2003 ◽  
Vol 20 (1) ◽  
pp. 16-18 ◽  
Author(s):  
Andrzej Marecki ◽  
Peter D. Barthel ◽  
Antonis Polatidis ◽  
Izabela Owsianik
Keyword(s):  
Radio Galaxy ◽  
Extreme Case ◽  
Double Object ◽  
Radio Structure ◽  
Double Structure ◽  
The Core ◽  
Vlbi Observations ◽  
New Phase

AbstractAGN with the so-called 'double-double' radio structure have been interpreted as restarted AGN where the inner structure is a manifestation of a new phase of activity which happened to begin before the outer radio lobes resulting from the previous one had faded completely. The radio galaxy 1245+676 is an extreme example of such a double-double object — its outer structure, measuring 970 h−1 kpc, is five orders of magnitude larger than the 9.6 h−1 pc inner one. We present a series of VLBI observations of the core of 1245+676 which appears to be a compact symmetric object (CSO). We have detected the motion of the CSOs lobes, measured its velocity, and inferred the kinematic age of that structure.

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