scholarly journals A Survey of Extended Radio Jets in Active Galactic Nuclei withChandraand theHubble Space Telescope: First Results

2002 ◽  
Vol 571 (1) ◽  
pp. 206-217 ◽  
Author(s):  
Rita M. Sambruna ◽  
L. Maraschi ◽  
F. Tavecchio ◽  
C. Megan Urry ◽  
C. C. Cheung ◽  
...  
Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 15
Author(s):  
Xiang Liu ◽  
Xin Wang ◽  
Ning Chang ◽  
Jun Liu ◽  
Lang Cui ◽  
...  

Two dozens of radio loud active galactic nuclei (AGNs) have been observed with Urumqi 25 m radio telescope in order to search for intra-day variability (IDV). The target sources are blazars (namely flat spectrum radio quasars and BL Lac objects) which are mostly selected from the observing list of RadioAstron AGN monitoring campaigns. The observations were carried out at 4.8 GHz in two sessions of 8–12 February 2014 and 7–9 March respectively. We report the data reduction and the first results of observations. The results show that the majority of the blazars exhibit IDV in 99.9% confidence level, some of them show quite strong IDV. We find the strong IDV of blazar 1357 + 769 for the first time. The IDV at centimeter-wavelength is believed to be predominately caused by the scintillation of blazar emission through the local interstellar medium in a few hundreds parsecs away from Sun. No significant correlation between the IDV strength and either redshift or Galactic latitude is found in our sample. The IDV timescale along with source structure and brightness temperature analysis will be presented in a forthcoming paper.


2019 ◽  
Vol 630 ◽  
pp. A108 ◽  
Author(s):  
C. Spingola ◽  
J. P. McKean ◽  
D. Massari ◽  
L. V. E. Koopmans

In this paper, we exploit the gravitational lensing effect to detect proper motion in the highly magnified gravitationally lensed source MG B2016+112. We find positional shifts up to 6 mas in the lensed images by comparing two Very Long Baseline Interferometric (VLBI) radio observations at 1.7 GHz that are separated by 14.359 years, and provide an astrometric accuracy of the order of tens of μas. From lens modelling, we exclude a shift in the lensing galaxy as the cause of the positional change of the lensed images, and we assign it to the background source. The source consists of four sub-components separated by ∼175 pc, with proper motion of the order of tens μas yr−1 for the two components at highest magnification (μ ∼ 350) and of the order of a few mas yr−1 for the two components at lower magnification (μ ∼ 2). We propose single active galactic nuclei (AGN) and dual AGN scenarios to explain the source plane. Although, the latter interpretation is supported by the archival multi-wavelength properties of the object. In this case, MG B2016+112 would represent the highest redshift dual radio-loud AGN system discovered thus far, and would support the merger interpretation for such systems. Also, given the low probability (∼10−5) of detecting a dual AGN system that is also gravitationally lensed, if confirmed, this would suggest that such dual AGN systems must be more abundant in the early Universe than currently thought.


1986 ◽  
Vol 64 (4) ◽  
pp. 434-439 ◽  
Author(s):  
J. F. C. Wardle ◽  
D. H. Roberts

We present some first results of a program to map the distribution of linear polarization in compact radio sources with milliarcsecond resolution. We show first-epoch maps of 3C345 and 0735 + 178 and first- and second-epoch maps of OJ287. In general, the polarization is mainly associated with optically thin (jet) components. In the case of OJ287, polarization maps made 1 year apart are strikingly different. We also discuss some of the theoretical issues raised by these observations.


2020 ◽  
Vol 496 (2) ◽  
pp. 1706-1717 ◽  
Author(s):  
Stanislav S Shabala ◽  
Nika Jurlin ◽  
Raffaella Morganti ◽  
Marisa Brienza ◽  
Martin J Hardcastle ◽  
...  

ABSTRACT Feedback from radio jets associated with active galactic nuclei (AGNs) plays a profound role in the evolution of galaxies. Kinetic power of these radio jets appears to show temporal variation, but the mechanism(s) responsible for this process are not yet clear. Recently, the LOw Frequency ARray (LOFAR) has uncovered large populations of active, remnant, and restarted radio jet populations. By focusing on LOFAR data in the Lockman Hole, in this work we use the Radio AGNs in Semi-Analytic Environments (RAiSE) dynamical model to present the first self-consistent modelling analysis of active, remnant, and restarted radio source populations. Consistent with other recent work, our models predict that remnant radio lobes fade quickly. Any high (>10 per cent) observed fraction of remnant and restarted sources therefore requires a dominant population of short-lived jets. We speculate that this could plausibly be provided by feedback-regulated accretion.


1998 ◽  
Vol 117 (1) ◽  
pp. 25-88 ◽  
Author(s):  
Matthew A. Malkan ◽  
Varoujan Gorjian ◽  
Raymond Tam

2004 ◽  
Vol 154 (1) ◽  
pp. 166-169 ◽  
Author(s):  
M. Lacy ◽  
L. J. Storrie‐Lombardi ◽  
A. Sajina ◽  
P. N. Appleton ◽  
L. Armus ◽  
...  

2004 ◽  
Vol 150 (1) ◽  
pp. 165-180 ◽  
Author(s):  
Joanna K. Kuraszkiewicz ◽  
Paul J. Green ◽  
D. Michael Crenshaw ◽  
Jay Dunn ◽  
Karl Forster ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document