The Jets in Radio Galaxy B1308–441

1996 ◽  
Vol 13 (3) ◽  
pp. 218-226 ◽  
Author(s):  
Paul A. Jones
Keyword(s):  
Radio Galaxy ◽  
Radio Galaxies ◽  
Class I ◽  
Bright Spot ◽  
The Core ◽  
Compact Array

AbstractThe giant radio galaxy B1308–441 has prominent two-sided jets, typical of Fanaroff–Riley class I radio galaxies, but there is an unusual bright spot in the SE jet 2 arcmin from the core that gives a marked asymmetry to the source. Observations at 1·37 and 2·37 GHz with the Australia Telescope Compact Array show that the bright spot has a flattened spectrum and high polarisation, and changes the direction of the SE jet. There is a diffuse optical object close to the bright spot which may be related to a shock in the jet.

scholarly journals FR I Jets in Southern Radio Galaxies

1996 ◽  
Vol 175 ◽  
pp. 143-144
Author(s):  
Paul A. Jones ◽  
Ben D. Lloyd
Keyword(s):  
Radio Galaxies ◽  
Class I ◽  
Sky Survey ◽  
Extended Sources ◽  
Optical Identifications ◽  
Compact Array

Sources flagged as extended or multiple in the Molonglo Reference Catalogue (MRC, Large et al. 1981, 1991), south of δ = −30°, were observed with the Molonglo Observatory Synthesis Telescope (MOST) with a resolution of 44 arcsec at 843 MHz (Jones and McAdam 1992) to give a sample of 193 southern extended sources. Optical identifications were made using the UKST bJ sky survey. We are now using the Australia Telescope Compact Array (ATCA) near Narrabri in Australia to study a subsample of Fanaroff-Riley class I radio galaxies and fit models to the jets.

Remnant radio galaxies discovered in a multi-frequency survey

2021 ◽  
Vol 38 ◽  
Author(s):  
Benjamin Quici ◽  
Natasha Hurley-Walker ◽  
Nicholas Seymour ◽  
Ross J. Turner ◽  
Stanislav S. Shabala ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Radio Galaxy ◽  
Radio Galaxies ◽  
Low Surface Brightness ◽  
Show Evidence ◽  
Frequency Survey ◽  
Square Kilometer Array ◽  
Murchison Widefield Array ◽  
Limiting Case ◽  
Compact Array

Abstract The remnant phase of a radio galaxy begins when the jets launched from an active galactic nucleus are switched off. To study the fraction of radio galaxies in a remnant phase, we take advantage of a $8.31$ deg $^2$ subregion of the GAMA 23 field which comprises of surveys covering the frequency range 0.1–9 GHz. We present a sample of 104 radio galaxies compiled from observations conducted by the Murchison Widefield Array (216 MHz), the Australia Square Kilometer Array Pathfinder (887 MHz), and the Australia Telescope Compact Array (5.5 GHz). We adopt an ‘absent radio core’ criterion to identify 10 radio galaxies showing no evidence for an active nucleus. We classify these as new candidate remnant radio galaxies. Seven of these objects still display compact emitting regions within the lobes at 5.5 GHz; at this frequency the emission is short-lived, implying a recent jet switch off. On the other hand, only three show evidence of aged lobe plasma by the presence of an ultra-steep-spectrum ( $\alpha<-1.2$ ) and a diffuse, low surface brightness radio morphology. The predominant fraction of young remnants is consistent with a rapid fading during the remnant phase. Within our sample of radio galaxies, our observations constrain the remnant fraction to $4\%\lesssim f_{\mathrm{rem}} \lesssim 10\%$ ; the lower limit comes from the limiting case in which all remnant candidates with hotspots are simply active radio galaxies with faint, undetected radio cores. Finally, we model the synchrotron spectrum arising from a hotspot to show they can persist for 5–10 Myr at 5.5 GHz after the jets switch of—radio emission arising from such hotspots can therefore be expected in an appreciable fraction of genuine remnants.

scholarly journals Active Galaxies and Candidate Remnants in the Core of the Shapley Concentration

2002 ◽  
Vol 199 ◽  
pp. 161-162
Author(s):  
T. Venturi ◽  
S. Bardelli ◽  
D. Dallacasa ◽  
R.W. Hunstead ◽  
R. Morganti ◽  
...  
Keyword(s):  
Spectral Properties ◽  
Radio Galaxies ◽  
Active Galaxies ◽  
Radio Sources ◽  
Nuclear Activity ◽  
The Core ◽  
Radio Jets ◽  
Extended Radio ◽  
Cluster Mergers ◽  
Compact Array

We present preliminary results of a multifrequency and multiresolution study carried out with the Australia Telescope Compact Array for nine of the ten extended radio galaxies located in the merging cluster complexes A3558 and A3528, at the centre of the Shapley Concentration. We found that 5 out of the 9 extended radio galaxies are active radio galaxies, i.e. they have a clear active radio nucleus coincident with the central region of the associated optical galaxy, radio jets and extended lobes; the remaining four lack an obvious radio nucleus, have a very diffuse and amorphous morphology and exhibit peculiar spectral properties. We call these radio sources as remnants and propose that they are (a) either radio galaxies where the nuclear activity has ceased; or (b) regions where pre-existing electrons have been reaccelerated as consequence of shocks due to cluster mergers.

scholarly journals Relativistic Jets in Low Power Radio Galaxies

1998 ◽  
Vol 164 ◽  
pp. 85-86 ◽  
Author(s):  
G. Giovannini ◽  
E. Arbizzani ◽  
L. Feretti ◽  
T. Venturi ◽  
W.D. Cotton ◽  
...  
Keyword(s):  
Low Power ◽  
Radio Galaxy ◽  
Morphological Changes ◽  
Radio Galaxies ◽  
Relativistic Jets ◽  
Radio Structure ◽  
The Core ◽  
Vlbi Observations ◽  
Relativistic Jet ◽  
Superluminal Motion

AbstractFrom VLBI observations of 11 FR I radio galaxies we find that: 1. parsec scale jets are relativistic; 2. 3C 264 shows a relativistic jet decelerating moving from the core to the extended lobes; 3. 3C 338 is a source with asymmetric parsec scale structure and morphological changes, implying proper motion on both sides of the source; 4. 1144+35 is an extended low power radio galaxy with an apparent superluminal motion in its parsec scale radio structure.

scholarly journals LOFAR measures the hotspot advance speed of the high-redshift blazar S5 0836+710

2019 ◽  
Vol 631 ◽  
pp. A49 ◽  
Author(s):  
A. Kappes ◽  
M. Perucho ◽  
M. Kadler ◽  
P. R. Burd ◽  
L. Vega-García ◽  
...  
Keyword(s):  
Spectral Index ◽  
Intergalactic Medium ◽  
Radio Galaxy ◽  
High Redshift ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Emission Region ◽  
Physical Parameters ◽  
The Core ◽  
Advance Speed

Context. The emission and proper motion of the terminal hotspots of active galactic nucleus (AGN) jets can be used as a powerful probe of the intergalactic medium. However, measurements of hotspot advance speeds in active galaxies are difficult, especially in the young universe, because of the low angular velocities and the low brightness of distant radio galaxies. Aims. Our goal is to study the termination of an AGN jet in the young universe and to deduce physical parameters of the jet and the intergalactic medium. Methods. We used the LOw Frequency ARray (LOFAR) to image the long-wavelength radio emission of the high-redshift blazar S5 0836+710 on arcsecond scales between 120 MHz and 160 MHz. Results. The LOFAR image shows a compact unresolved core and a resolved emission region about 1.5 arcsec to the southwest of the radio core. This structure is in general agreement with previous higher-frequency radio observations with the Multi-Element Radio-Linked Interferometer Network (MERLIN) and the Very Large Array (VLA). The southern component shows a moderately steep spectrum with a spectral index of about ≳ − 1, and the spectral index of the core is flat to slightly inverted. In addition, we detect for the first time a resolved steep-spectrum halo with a spectral index of about −1 surrounding the core. Conclusions. The arcsecond-scale radio structure of S5 0836+710 can be understood as a Faranoff–Riley (FR) II radio galaxy observed at a small viewing angle. The southern component can be interpreted as the region of the approaching jet’s terminal hotspot, and the halo like diffuse component near the core can be interpreted as the counter-hotspot region. From the differential Doppler boosting of both features, we can derive the hotspot advance speed to (0.01 − 0.036) c. At a constant advance speed, the derived age of the source would exceed the total lifetime of such a powerful FR II radio galaxy substantially. Thus, the hotspot advance speed must have been higher in the past, in agreement with a scenario in which the originally highly relativistic jet has lost collimation as a result of instability growth and has transformed into an only mildly relativistic flow. Our data suggest that the density of the intergalactic medium around this distant (z = 2.22) AGN could be substantially higher than the values typically found in less distant FR II radio galaxies.

scholarly journals Structure of the magnetoionic medium around the Fanaroff-Riley Class I radio galaxy 3C 449

2010 ◽  
Vol 514 ◽  
pp. A50 ◽  
Author(s):  
D. Guidetti ◽  
R. A. Laing ◽  
M. Murgia ◽  
F. Govoni ◽  
L. Gregorini ◽  
...  
Keyword(s):  
Radio Galaxy ◽  
Class I

scholarly journals Radio Spectra and Particle Ages of the Head-Tail Radio Galaxy NGC1265

1996 ◽  
Vol 175 ◽  
pp. 347-348
Author(s):  
L. Feretti ◽  
G. Giovannini ◽  
U. Klein ◽  
K.-H. Mack ◽  
L.G. Sijbring
Keyword(s):  
Magnetic Field ◽  
Radio Galaxy ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Field Structure ◽  
Magnetic Field Structure ◽  
Linearly Polarized ◽  
Faraday Effects ◽  
Perseus Cluster ◽  
Comprehensive Study

We have performed sensitive observations of three classical head-tail radio galaxies at λ11.1, 6.3, and 2.8 cm using the Effelsberg 100-m telescope (Zech, 1994). Complete maps of the sources 3C129, NGC1265, and 3C465 were obtained, including the distributions of the linearly polarized intensity. Together with the low-frequency interferometric maps these allow a comprehensive study of their radio spectra and, based on models of particle losses, the derivations of particle ages across these sources. The highest frequency involved allows an unambiguous derivation of the projected magnetic field structure, unimpeded by Faraday effects. Here we focus on NGC1265, which is located in the Perseus Cluster.

Bending of the pc scale jet in 3C84

2018 ◽  
Vol 14 (S342) ◽  
pp. 239-241
Author(s):  
A. Hirano ◽  
K. Fujisawa ◽  
K. Niinuma ◽  
Keyword(s):  
Time Scale ◽  
Radio Galaxy ◽  
Brightness Distribution ◽  
Vlbi Observation ◽  
The Core ◽  
Long Period ◽  
Structure Changes ◽  
Observation Network ◽  
Real Change ◽  
Jet Structure

AbstractWe have conducted VLBI monitoring observations for a radio galaxy 3C 84 to investigate how the pc scale jet structure changes over a long period. VERA, a VLBI observation network in Japan, was used for the observation. The C3 component of the jet has continuously moved toward the south from the core. The motion was, however, not straight, but it showed a bending of about 0.3 mas (0.1 pc) with a time scale of 500-1000 days. Two models explaining the bending, local brightness distribution change or real change of the jet traveling direction, are discussed.

scholarly journals Interferometry of class I methanol masers, statistics and the distance scale

2017 ◽  
Vol 13 (S336) ◽  
pp. 158-161
Author(s):  
Maxim A. Voronkov ◽  
Shari L. Breen ◽  
Simon P. Ellingsen ◽  
Christopher H. Jordan
Keyword(s):  
Angular Resolution ◽  
Class I ◽  
High Angular Resolution ◽  
Current Form ◽  
Young Stellar Object ◽  
Linear Distance ◽  
Kinematic Method ◽  
Future Potential ◽  
Methanol Masers ◽  
Compact Array

AbstractThe Australia Telescope Compact Array (ATCA) participated in a number of survey programs to search for and image common class I methanol masers (at 36 and 44 GHz) with high angular resolution. In this paper, we discuss spatial and velocity distributions revealed by these surveys. In particular, the number of maser regions is found to fall off exponentially with the linear distance from the associated young stellar object traced by the 6.7-GHz maser, and the scale of this distribution is 263±15 milliparsec. Although this relationship still needs to be understood in the context of the broader field, it can be utilised to estimate the distance using methanol masers only. This new technique has been analysed to understand its limitations and future potential. It turned out, it can be very successful to resolve the ambiguity in kinematic distances, but, in the current form, is much less accurate (than the kinematic method) if used on its own.

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