scholarly journals DEEPSPITZEROBSERVATIONS OF INFRARED-FAINT RADIO SOURCES: HIGH-REDSHIFT RADIO-LOUD ACTIVE GALACTIC NUCLEI?

2011 ◽  
Vol 736 (1) ◽  
pp. 55 ◽  
Author(s):  
Ray P. Norris ◽  
Jose Afonso ◽  
Antonio Cava ◽  
Duncan Farrah ◽  
Minh T. Huynh ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
High Redshift ◽  
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.

scholarly journals Quasi Stellar Objects and Active Galactic Nuclei

1984 ◽  
Vol 78 ◽  
pp. 443-456
Author(s):  
C. Barbieri
Keyword(s):  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Physical Processes ◽  
Stellar Objects ◽  
Sky Survey ◽  
Quasi Stellar Objects ◽  
The One

The role of the Schmidt telescopes in the discovery of the Quasi Stellar Objects and of the Active Galactic Nuclei, and in the understanding of their properties was and continues to be of the greatest importance. Thousands of Radio-Sources have been quickly associated to their optical counterparts thanks to the worldwide availability of the Palomar Observatory Sky Survey plates and charts and more recently of the films of the ESO B Survey. Other thousands of QSOs and AGNs devoid of radio emission are found by the large Schmidts nowaday in operation. This wealth of data give fundamental cosmological knowledge and insight in the physical processes occuring in these objects. I'll concentrate in this Review on two specific topics, namely on the discovery techniques and on the study of the optical variability. To both subjects, the 67/92 cm Schmidt telescope here at Asiago has made significant contributions. The first topic is treated in several excellent papers, such as the one by M. Smith (1978) and the one by P. Veron (1983); the material presented in the second part is largely new. In the following, I'll use rather loosely the terms QSOs and AGNs to designate a variety of objects including Quasars (those QSOs in catalogs of Radio-Sources), high-redshift compact galaxies with emission lines, BL LACset similia.

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 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

scholarly journals Constraints on the production and escape of ionizing radiation from the emission-lines of metal-poor star-forming galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 121-122
Author(s):  
A. Plat ◽  
S. Charlot ◽  
G. Bruzual ◽  
A. Feltre ◽  
A. Vidal-Garca ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Radiative Shocks ◽  
Metal Poor Star

AbstractTo understand how the nature of the ionizing sources and the leakage of ionizing photons in high-redshift galaxies can be constrained from their emission-line spectra, we compare emission-line models of star-forming galaxies including leakage of ionizing radiation, active galactic nuclei (AGN) and radiative shocks, with observations of galaxies at various redshifts with properties expected to approach those of primeval galaxies.

scholarly journals HEAVILY OBSCURED ACTIVE GALACTIC NUCLEI IN HIGH-REDSHIFT LUMINOUS INFRARED GALAXIES

2010 ◽  
Vol 722 (2) ◽  
pp. L238-L243 ◽  
Author(s):  
Ezequiel Treister ◽  
C. Megan Urry ◽  
Kevin Schawinski ◽  
Carolin N. Cardamone ◽  
David B. Sanders
Keyword(s):  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Infrared Galaxies ◽  
Luminous Infrared Galaxies

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 The Distant DRAGNs Survey

1996 ◽  
Vol 175 ◽  
pp. 513-514
Author(s):  
J. D. B. Law-Green
Keyword(s):  
Flux Density ◽  
Ambient Medium ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Cosmological Evolution ◽  
Radio Sources ◽  
Number Density ◽  
Extragalactic Radio Sources ◽  
Matched Samples

DRAGNs (Double Radio sources Associated with Galactic Nuclei, Leahy 1991) are the class of powerful extragalactic radio sources thought to be produced by the interaction of a jet with the ambient medium. They exhibit strong cosmological evolution in comoving number density; at z ≃ 2 the “classical double” FR II DRAGNs were ≃ 1000 times as common as they are now (Dunlop & Peacock 1990).To understand this, systematic studies of complete DRAGN samples at low and high z and differing levels of flux density are required, in order to resolve the P – z ambiguity. The Distant DRAGNs Survey is a long-term project to image with the VLA and MERLIN, matched samples of DRAGNs at high redshift.

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