scholarly journals Probing the pc- and kpc-scale Environment of the Powerful Radio Galaxy Hercules A

2002 ◽  
Vol 19 (1) ◽  
pp. 69-72 ◽  
Author(s):  
Nectaria A. B. Gizani ◽  
M. A. Garrett ◽  
J. P. Leahy
Keyword(s):  
Radio Source ◽  
Radio Galaxy ◽  
Angular Size ◽  
Position Angle ◽  
Extragalactic Radio Source ◽  
X Ray ◽  
Central Value ◽  
Intracluster Gas ◽  
Extended Emission ◽  
Powerful Radio Galaxy

AbstractWe present the kpc-scale behaviour of the powerful extragalactic radio source Hercules A and the behaviour of the intracluster gas in which the radio source is situated. We have found that Hercules A exhibits a strong Laing-Garrington effect. The X-ray observations have revealed an extended X-ray emission elongated along the radio galaxy axis. The estimated temperature of the cluster is kT=2.45 keV and the central electron density is n○≃7.8×10−3 cm−3 which reveals a hot, dense environment in which Hercules A is situated. From the combined study of the radio and X-ray data we have estimated a central value of 3 ≲ B○(μG)≲9.We also present the most recent results from the analysis of the radio data on the pc-scale structure of the radio galaxy, observed at 18 cm by the EVN–MERLIN array. A faint but compact radio source, coincident with the optical centre of Hercules A, was detected by the EVN at 18 mas resolution. The total flux density of the EVN core is 14.6 mJy. Its angular size is 18×7 mas with a position angle of ≃139°. There is also evidence for extended emission in the NW–SE direction, most probably from the eastern pc-scale jet. If this is true then there is a misalignment between the direction of the pc-eastern and the aligned kpc-scale jets of ≃35°.

scholarly journals X-ray emission from the extended emission-line region of the powerful radio galaxy 3C 171

2010 ◽  
Vol 401 (4) ◽  
pp. 2697-2705 ◽  
Author(s):  
M. J. Hardcastle ◽  
F. Massaro ◽  
D. E. Harris
Keyword(s):  
Emission Line ◽  
Radio Galaxy ◽  
Powerful Radio ◽  
X Ray ◽  
Line Region ◽  
Extended Emission ◽  
Powerful Radio Galaxy

scholarly journals Radio and X-ray Observations of the Restarted Radio Galaxy in the Galaxy Cluster CL 0838+1948

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 108
Author(s):  
Simona Giacintucci ◽  
Tracy Clarke ◽  
Namir E. Kassim ◽  
Wendy Peters ◽  
Emil Polisensky
Keyword(s):  
Radio Source ◽  
Survey Data ◽  
Radio Galaxy ◽  
Galaxy Cluster ◽  
Gas Emission ◽  
Low Frequencies ◽  
Nuclear Activity ◽  
X Ray ◽  
Hot Gas ◽  
The Galaxy

We present VLA Low-band Ionosphere and Transient Experiment (VLITE) 338 MHz observations of the galaxy cluster CL 0838+1948. We combine the VLITE data with Giant Metrewave Radio Telescope 610 MHz observations and survey data. The central galaxy hosts a 250 kpc source whose emission is dominated by two large lobes at low frequencies. At higher frequencies, a pair of smaller lobes (∼30 kpc) is detected within the galaxy optical envelope. The observed morphology is consistent with a restarted radio galaxy. The outer lobes have a spectral index αout=1.6, indicating that they are old, whereas the inner lobes have αinn=0.6, typical for an active source. Spectral modeling confirms that the outer emission is a dying source whose nuclear activity switched off not more than 110 Myr ago. Using archival Chandra X-ray data, we compare the radio and hot gas emission. We find that the active radio source is contained within the innermost and X-ray brightest region, possibly a galactic corona. Alternatively, it could be the remnant of a larger cool core whose outer layers have been heated by the former epoch of activity that has generated the outer lobes.

scholarly journals A young and obscured AGN embedded in the giant radio galaxy Mrk 1498

2019 ◽  
Author(s):  
L Hernández-García ◽  
F Panessa ◽  
L Bassani ◽  
G Bruni ◽  
F Ursini ◽  
...  
Keyword(s):  
Large Scale ◽  
Radio Galaxy ◽  
Conclusive Evidence ◽  
X Rays ◽  
Nuclear Activity ◽  
X Ray ◽  
Multi Wavelength ◽  
Tidal Streams ◽  
A Minor ◽  
Extended Emission

Abstract Mrk 1498 is part of a sample of galaxies with extended emission line regions (extended outwards up to a distance of ∼7 kpc) suggested to be photo-ionized by an AGN that has faded away or that is still active but heavily absorbed. Interestingly, the nucleus of Mrk 1498 is at the center of two giant radio lobes with a projected linear size of 1.1 Mpc. Our multi-wavelength analysis reveals a complex nuclear structure, with a young radio source (Giga-hertz Peaked Spectrum) surrounded by a strong X-ray nuclear absorption, a mid-infrared spectrum that is dominated by the torus emission, plus a circum-nuclear extended emission in the [OIII] image (with radius of ∼ 1 kpc), most likely related to the ionization of the AGN, aligned with the small and large scale radio jet and extended also at X-rays. In addition a large-scale extended emission (up to ∼ 10 kpc) is only visible in [OIII]. These data show conclusive evidence of a heavily absorbed nucleus and has recently restarted its nuclear activity. To explain its complexity, we propose that Mrk 1498 is the result of a merging event or secular processes, such as a minor interaction, that has triggered the nuclear activity and produced tidal streams. The large-scale extended emission that gives place to the actual morphology could either be explained by star formation or outflowing material from the AGN.

scholarly journals The ASCA X-ray spectrum of the powerful radio galaxy 3C 109

1997 ◽  
Vol 286 (3) ◽  
pp. 765-770 ◽  
Author(s):  
S. W. Allen ◽  
A. C. Fabian ◽  
E. Idesawa ◽  
H. Inoue ◽  
T. Kii ◽  
...  
Keyword(s):  
Radio Galaxy ◽  
Powerful Radio ◽  
X Ray ◽  
Powerful Radio Galaxy

scholarly journals Extended and Compact X‐Ray Emission from the Powerful Radio Galaxy 3C 220.1

1998 ◽  
Vol 504 (2) ◽  
pp. 743-748 ◽  
Author(s):  
M. J. Hardcastle ◽  
C. R. Lawrence ◽  
D. M. Worrall
Keyword(s):  
Radio Galaxy ◽  
Powerful Radio ◽  
X Ray ◽  
Powerful Radio Galaxy

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 Emission Regions in Centaurus A

1982 ◽  
Vol 97 ◽  
pp. 115-116
Author(s):  
R. M. Price ◽  
J. A. Graham
Keyword(s):  
Radio Source ◽  
Faraday Rotation ◽  
Linear Polarization ◽  
Radio Galaxy ◽  
Radio Galaxies ◽  
Extragalactic Radio Source ◽  
Physical Mechanisms ◽  
Centaurus A

Centaurus A, at an estimated distance of five megaparsecs, is the closest radio galaxy. It presents the best opportunity to examine in detail the physical mechanisms and resulting structures that are to be found in radio galaxies. Centaurus was first studied in detail at radio wavelengths by Cooper, Price and Cole (1965), hence CPC. Many of the comments, interpretations, and conclusions recorded in that paper remain valid today and provide the broader framework in which the more detailed studies using today's more powerful instrumentation can be understood. Historically, it is also interesting to note that Centaurus A was the first extragalactic radio source in which linear polarization and Faraday rotation were discovered and extensively studied.

scholarly journals Cygnus A ? John Bolton?s First Cosmic Source

1994 ◽  
Vol 47 (5) ◽  
pp. 615 ◽  
Author(s):  
DE Harris
Keyword(s):  
Radio Galaxy ◽  
Discrete Source ◽  
X Rays ◽  
Powerful Radio ◽  
X Ray ◽  
Cygnus A ◽  
Cosmic Source ◽  
Powerful Radio Galaxy

Using a sea interferometer, Bolton and Stanley isolated Cygnus A as a discrete source in 1948. It is a prime example� of a powerful radio galaxy and, in the last decade, has also been studied extensively in X-rays. In this paper I summarise the results from a ROSAT X-ray image.

Spectra of Radio Galaxies in Clusters

1982 ◽  
Vol 4 (4) ◽  
pp. 431-434 ◽  
Author(s):  
O. B. Slee ◽  
I. R. G. Wilson ◽  
Betty C. Siegman
Keyword(s):  
Electron Density ◽  
Radio Galaxy ◽  
Radio Galaxies ◽  
Relativistic Electrons ◽  
Number Of Clusters ◽  
X Ray ◽  
Thermal Spectrum ◽  
Cluster Centre ◽  
Intracluster Gas

There has been considerable speculation in recent years about the evolution of radio galaxies in clusters. The discovery of powerful X-ray emission with an apparently thermal spectrum from a considerable number of clusters has been attributed to a hot (108K) intracluster gas with an electron density of ∼ 10-3 cm -3 at the cluster centre (see e.g. McHardy 1978). Such a gas surrounding a radio galaxy may conceivably retard the expansion or diffusion of the relativistic electrons and thus allow the source to retain its identity for longer intervals than is the case for field galaxies.

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