scholarly journals EVIDENCE FOR INFRARED-FAINT RADIO SOURCES ASz> 1 RADIO-LOUD ACTIVE GALACTIC NUCLEI

2010 ◽  
Vol 710 (1) ◽  
pp. 698-705 ◽  
Author(s):  
Minh T. Huynh ◽  
Ray P. Norris ◽  
Brian Siana ◽  
Enno Middelberg
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Sources

The GLEAM 4-Jy Sample: The brightest radio-sources in the southern sky

2019 ◽  
Vol 15 (S356) ◽  
pp. 375-375
Author(s):  
Sarah White
Keyword(s):  
Radio Emission ◽  
Active Galactic Nuclei ◽  
Visual Inspection ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Relativistic Jets ◽  
The Galaxy ◽  
Murchison Widefield Array ◽  
Past Activity

AbstractLow-frequency radio emission allows powerful active galactic nuclei (AGN) to be selected in a way that is unaffected by dust obscuration and orientation of the jet axis. It also reveals past activity (e.g. radio lobes) that may not be evident at higher frequencies. Currently, there are too few “radio-loud” galaxies for robust studies in terms of redshift-evolution and/or environment. Hence our use of new observations from the Murchison Widefield Array (the SKA-Low precursor), over the southern sky, to construct the GLEAM 4-Jy Sample (1,860 sources at S151MHz > 4 Jy). This sample is dominated by AGN and is 10 times larger than the heavily relied-upon 3CRR sample (173 sources at S178MHz > 10 Jy) of the northern hemisphere. In order to understand how AGN influence their surroundings and the way galaxies evolve, we first need to correctly identify the galaxy hosting the radio emission. This has now been completed for the GLEAM 4-Jy Sample – through repeated visual inspection and extensive checks against the literature – forming a valuable, legacy dataset for investigating relativistic jets and their interplay with the environment.

scholarly journals Simulations of Relativistic Jet Formation in Compact Radio Sources

2001 ◽  
Vol 205 ◽  
pp. 18-19
Author(s):  
David L. Meier
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Jet Formation ◽  
Analytic Work ◽  
Relativistic Jet ◽  
Mhd Model ◽  
Relativistic Outflows

I review recent numerical and analytic work on the magnetohydrodynamic (MHD) model of jet formation in active galactic nuclei, with an emphasis on producing the highly relativistic outflows and high radio luminosities observed in the most powerful sources.

scholarly journals Statistical Effects of Doppler Beaming and Malmquist Bias on Flux-Limited Samples of Compact Radio Sources

1998 ◽  
Vol 164 ◽  
pp. 137-138
Author(s):  
Matthew L. Lister ◽  
Alan P. Marscher
Keyword(s):  
Active Galactic Nuclei ◽  
Luminosity Function ◽  
Galactic Nuclei ◽  
Lorentz Factor ◽  
Radio Sources ◽  
Apparent Velocity ◽  
Parent Population ◽  
Relativistic Jet ◽  
Spectrum Radio ◽  
Statistical Effects

AbstractWe examine the effects of Doppler beaming on flux-limited samples of compact extragalactic radio sources using Monte Carlo simulations. We incorporate a luminosity function and z-distribution for the parent population, and investigate models in which the unbeamed synchrotron luminosity L of a relativistic jet is related to its bulk Lorentz factor Γ. The predicted flux density, redshift, monochromatic luminosity, and apparent velocity distributions of our simulated flux-limited samples are compared to the Caltech-Jodrell Bank (CJF) sample of flat-spectrum, radio core-dominated active galactic nuclei (AGNs).We find that a relation between L and Γ is not needed to reproduce the characteristics of the CJF sample. Introducing a positive correlation between these quantities results in an underabundance of objects with high viewing angles, while a negative correlation gives generally poor fits to the data.

scholarly journals Expanding Quasars and the Expansion of the Universe

1988 ◽  
Vol 129 ◽  
pp. 23-24
Author(s):  
M. H. Cohen ◽  
P. D. Barthel ◽  
T. J. Pearson ◽  
J. A. Zensus
Keyword(s):  
Active Galactic Nuclei ◽  
Upper Bound ◽  
Proper Motion ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Extragalactic Radio Sources ◽  
Expansion Of The Universe ◽  
The Universe

The μ–z diagram (Figure 1) plots the observed internal proper motion μ versus redshift z for 32 extragalactic radio sources associated with active galactic nuclei. The observed points fall below an upper bound which decreases with redshift; there is a statistically significant anticorrelation between redshift and internal proper motion.

scholarly journals VSOP, A Space VLBI Programme

1990 ◽  
Vol 123 ◽  
pp. 263-269
Author(s):  
H. Hirabayashi
Keyword(s):  
Active Galactic Nuclei ◽  
Phase Transfer ◽  
Galactic Nuclei ◽  
Satellite Orbit ◽  
Radio Sources ◽  
Space Observatory ◽  
Stellar Objects ◽  
Radio Observatory ◽  
Star Forming ◽  
Star Forming Regions

AbstractVSOP, VLBI Space Observatory Programme, is an approved space VLBI programme of ISAS for the study of very compact radio sources with the synthesized aperture of 30,000 km diameter, by connecting an orbiting radio observatory with ground radiotelescopes. The VSOP satellite carrying 10 m antenna with 1.6, 5, and 22 GHz band receivers will be launched in early 1995 by M-V rocket of ISAS into an eccentric orbit with 20,000 km in apogee height. The tracking network will be formed for the satellite orbit determination, phase transfer and IF down-link. VSOP aims imaging capability with best resolution of 0.0001 arc second in 22 GHz band. Imaging of active galactic nuclei, star forming regions and stellar objects, and radioastrometry are main scientific targets.

Very long baseline interferometry polarization studies of quasars and active galactic nuclei

1986 ◽  
Vol 64 (4) ◽  
pp. 434-439 ◽  
Author(s):  
J. F. C. Wardle ◽  
D. H. Roberts
Keyword(s):  
Active Galactic Nuclei ◽  
Linear Polarization ◽  
Very Long Baseline Interferometry ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Long Baseline ◽  
First Results ◽  
Polarization Studies ◽  
Theoretical Issues

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.

scholarly journals Polarization Distributions in Compact Radio Sources

1986 ◽  
Vol 119 ◽  
pp. 141-147
Author(s):  
David H. Roberts ◽  
John F. C. Wardle
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Bl Lacertae ◽  
The Galaxy ◽  
5 Ghz

We present milliarcsecond-resolution 5 GHz polarization maps of several active galactic nuclei: one epoch each for the quasar 3C345, the galaxy 3C120, and the BL Lacertae object 0735+178, and two epochs for the BL Lacertae object OJ287.

scholarly journals Radio sources in low-luminosity active galactic nuclei

2002 ◽  
Vol 392 (1) ◽  
pp. 53-82 ◽  
Author(s):  
N. M. Nagar ◽  
H. Falcke ◽  
A. S. Wilson ◽  
J. S. Ulvestad
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Sources

scholarly journals ASYMMETRIES OF AGN JETS IN INHOMOGENEOUS MEDIA

2014 ◽  
Vol 28 ◽  
pp. 1460192
Author(s):  
VOLKER GAIBLER
Keyword(s):  
Interstellar Medium ◽  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Inhomogeneous Media ◽  
Host Galaxy ◽  
Radio Sources ◽  
Propagation Models ◽  
Hydrodynamical Simulations

Considerable asymmetries in jets from active galactic nuclei (AGN) and associated double radio sources can be caused by an inhomogeneous interstellar medium of the host galaxy. These asymmetries can easily be estimated by 1D propagation models, but hydrodynamical simulations have shown that the actual asymmetries can be considerably larger. With a set of smaller-scale hydrodynamical simulations we examine these asymmetries, and find they are typically a factor of ~ 3 larger than in 1D models. We conclude that, at high redshift, large asymmetries in radio sources are expected in gas-rich galaxies with a clumpy interstellar medium.

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