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
1996 ◽  
Vol 175 ◽  
pp. 23-24
Author(s):  
D.L. Jones ◽  
S.J. Tingay ◽  
R.A. Preston ◽  
D.L. Jauncey ◽  
J.E. Reynolds ◽  
...  

Centaurus A (NGC 5128) is the nearest giant radio galaxy. It is a Fanaroff-Riley type 1 (low luminosity) radio source, but the compact radio source in the nucleus is strong enough that VLBI imaging has been possible with both the SHEVE array and the VLBA at several frequencies. These observations have detected a sub-parsec scale counterjet. This shows that jet formation in at least some FR I sources is intrinsically two-sided over very small distances and the radio jets in Centaurus A are probably only moderately relativistic. We also find evidence that the center of activity in Centaurus A is partially obscured by a disk or torus of dense plasma.


2003 ◽  
Vol 20 (1) ◽  
pp. 1-5 ◽  
Author(s):  
V. Safouris ◽  
R. W. Hunstead ◽  
O. R. Prouton

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.


2006 ◽  
Vol 648 (1) ◽  
pp. 148-157 ◽  
Author(s):  
Hiroshi Nagai ◽  
Makoto Inoue ◽  
Keiichi Asada ◽  
Seiji Kameno ◽  
Akihiro Doi

2013 ◽  
Vol 552 ◽  
pp. A109 ◽  
Author(s):  
S. Frey ◽  
Z. Paragi ◽  
K. É. Gabányi ◽  
T. An

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 108
Author(s):  
Simona Giacintucci ◽  
Tracy Clarke ◽  
Namir E. Kassim ◽  
Wendy Peters ◽  
Emil Polisensky

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.


Quasars ◽  
1986 ◽  
pp. 157-158
Author(s):  
J. Biretta ◽  
M. Cohen ◽  
R. Moore

1989 ◽  
Vol 136 ◽  
pp. 535-541 ◽  
Author(s):  
Jun-Hui Zhao ◽  
R. D. Ekers ◽  
W. M. Goss ◽  
K. Y. Lo ◽  
Ramesh Narayan

We investigate the long-term flux density variations of the compact radio source Sgr A∗ at the galactic center by combining recent VLA observations with previous Green Bank interferometer data. We present radio flux density light-curves for Sgr A∗ at 20, 11, 6 and 3.7 cm from 1974 to 1987. Long-term variability with a timescale of at least 5 years is seen at 20 cm and there is evidence for more rapid variations at the shorter wavelengths. The variability timescales at 20, 11 and 6 cm fit the λ2 scaling predicted by the theory of refractive scintillation suggesting that the variability could be due to this cause. However, the timescales are relatively short, implying an unusually high velocity in the scattering screen. The modulation index of the variability is large and relatively independent of wavelength.


1977 ◽  
Vol 218 ◽  
pp. 668 ◽  
Author(s):  
K. Y. Lo ◽  
M. H. Cohen ◽  
R. T. Schilizzi ◽  
H. N. Ross

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