scholarly journals SpitzerObservations of 3C Quasars and Radio Galaxies: Mid‐Infrared Properties of Powerful Radio Sources

2007 ◽  
Vol 660 (1) ◽  
pp. 117-145 ◽  
Author(s):  
K. Cleary ◽  
C. R. Lawrence ◽  
J. A. Marshall ◽  
L. Hao ◽  
D. Meier
Keyword(s):  
Radio Galaxies ◽  
Radio Sources ◽  
Powerful Radio ◽  
Mid Infrared ◽  
Quasars And Radio Galaxies

scholarly journals Extragalactic jets as probes of distant clusters of galaxies and the clusters occupied by bent radio AGN (COBRA) survey

2014 ◽  
Vol 10 (S313) ◽  
pp. 315-320
Author(s):  
Elizabeth L. Blanton ◽  
Rachel Paterno-Mahler ◽  
Joshua D. Wing ◽  
M. L. N. Ashby ◽  
Emmet Golden-Marx ◽  
...  
Keyword(s):  
Radio Galaxies ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Wide Range ◽  
Extragalactic Jets ◽  
Large Survey ◽  
Kinetic Mode ◽  
Group Environments ◽  
Initial Results ◽  
Quasars And Radio Galaxies

AbstractWe are conducting a large survey of distant clusters of galaxies using radio sources with bent jets and lobes as tracers. These radio sources are driven by AGN and achieve their bent morphologies through interaction with the surrounding gas found in clusters of galaxies. Based on low-redshift studies, these types of sources can be used to identify clusters very efficiently. We present initial results from our survey of 653 bent-double radio sources with optical hosts too faint to appear in the SDSS. The sample was observed in the infrared with Spitzer, and it has revealed ~200 distant clusters or proto-clusters in the redshift range z ~ 0.7 - 3.0. The sample of bent-doubles contains both quasars and radio galaxies enabling us to study both radiative and kinetic mode feedback in cluster and group environments at a wide range of redshifts.

scholarly journals Interpretation of Cosmological Information on Radio Sources

1977 ◽  
Vol 74 ◽  
pp. 247-257
Author(s):  
G. Burbidge
Keyword(s):  
Radio Astronomy ◽  
Background Radiation ◽  
Radio Galaxies ◽  
Radio Sources ◽  
List Type ◽  
Type Number ◽  
Radio Flux ◽  
Powerful Radio ◽  
Microwave Background ◽  
Microwave Background Radiation

The topic that I have to introduce today is concerned with the question as to whether or not we can obtain any cosmological information from radio astronomy. Alternatively, we may ask “Where does radio astronomy have an impact on cosmology?” There are several areas that must be discussed. They are: 1)The discovery and interpretation of the microwave background radiation.2)The identification of powerful radio sources and the discovery that many of them have large redshifts. If we can prove that the large redshifts mean that the objects are at great distances, then we can use these radio sources as follows:(a)We can attempt to obtain a Hubble relation for the optical objects which are identified with radio galaxies;(b)We can look for a relation between the angular diameters of the radio sources and the redshifts of the optically identified objects and we can also look at relations between the angular diameter and the radio flux;(c)We can construct log N - log S curves and we can carry out luminosity volume tests.

scholarly journals Bent Jets in Radio Quasars

1982 ◽  
Vol 97 ◽  
pp. 137-138
Author(s):  
Susan G. Neff
Keyword(s):  
Hot Spots ◽  
Radio Galaxies ◽  
Plasma Instability ◽  
Radio Sources ◽  
Central Engine ◽  
Central Nozzle ◽  
Quasars And Radio Galaxies

How is energy transported out from the central engine in quasars and radio galaxies to the distant radio lobes? This problem has been around since the early discovery of classical double radio sources, and is still not answered in detail. The idea of relativistic beams was first suggested by Martin Rees as a means of transporting plasma out of the nucleus (Rees, 1971, Blandford and Rees, 1974). This idea gained support first from the discovery of hot spots in the radio lobes of these large classical double sources, and later by observations of the beams themselves in radio galaxies. As more jets were observed, it became obvious that they were often curved, serpentine, or even sharply bent. This behavior has been modeled as precession of the central nozzle (Bridle et al., 1976, Ekers et al., 1978), as nuclear refraction (Henriksen et al., 1981), as a growing plasma instability (Hardee, 1981) and as various combinations of the above. At the present time, it seems safest to conclude that there are some examples of each of these processes known.

scholarly journals An Updated Multi-Wavelength Radio and Optical Catalog of Quasars and Radio Galaxies

2013 ◽  
Vol 9 (S304) ◽  
pp. 238-239 ◽  
Author(s):  
Amy E. Kimball ◽  
Željko Ivezić
Keyword(s):  
Spectral Index ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Large Area ◽  
Sky Surveys ◽  
The North ◽  
Multi Wavelength ◽  
Optical Surveys ◽  
Quasars And Radio Galaxies ◽  
North Galactic

AbstractWe present a catalog of millions of radio sources, created by consolidating large-area radio and optical surveys GB6 (6cm), FIRST (20cm), NVSS (20cm), WENSS (92cm), VLSS (4m), and SDSS DR9 (optical). The region where all surveys overlap covers 3269 deg2 in the North Galactic Cap, and contains >160,000 20-cm sources, with about 12,000 detected in all five radio surveys and over one-third detected optically. Combining parameters from the sky surveys allows easy and efficient classification by radio and optical morphology and radio spectral index. The catalog is available at http://www.atnf.csiro.au/people/Amy.Kimball/radiocat.shtml.

scholarly journals The Emission Line Properties of the 3CR Radio Galaxies at Redshift One: Shocks, Evolution, and the Alignment Effect

1999 ◽  
Vol 194 ◽  
pp. 241-245
Author(s):  
Philip Best ◽  
Huub Röttgering ◽  
Malcolm Longair
Keyword(s):  
Emission Line ◽  
Radio Source ◽  
Velocity Structure ◽  
Radio Galaxies ◽  
Linear Size ◽  
Continuum Emission ◽  
Radio Sources ◽  
Powerful Radio ◽  
Alignment Effect ◽  
Optical Continuum

The results of a deep spectroscopic campaign on powerful radio galaxies with redshifts z ˜ 1, to investigate in detail their emission line gas properties, are presented. Both the 2-dimensional velocity structure of the [OII] 3727 emission line and the ionisation state of the gas are found to be strongly dependent upon the linear size (age) of the radio source in a manner indicative of the emission line properties of small (young) radio sources being dominated by the passage of the radio source shocks. The consequences of this evolution throughout the few x107 year lifetime of the radio source are discussed, particularly with relation to the alignment of the UV–optical continuum emission of these objects along their radio axis, the nature of which shows similar evolution.

scholarly journals Episodic ejection from super-massive black holes

2006 ◽  
Vol 2 (S238) ◽  
pp. 441-442
Author(s):  
Lakshmi Saripalli ◽  
Ravi Subrahmanyan ◽  
Richard W. Hunstead
Keyword(s):  
Black Holes ◽  
Radio Galaxies ◽  
Supermassive Black Holes ◽  
Radio Sources ◽  
Powerful Radio ◽  
Massive Black Holes ◽  
Episodic Activity

AbstractEpisodic activity in super-massive black holes is shown by radio galaxies exhibiting ‘double-double’ radio morphologies (Subrahmanyan et al. 1996, Schoenmakers et al. 2000). Spectacular examples showing a renewal of beam activity in the form of new beams emerging within relic radio lobes of previous activity have placed the phenomenon of recurrence in AGN outflows on a firm footing.By using the SUMSS and WENSS GRG samples, we infer that on timescales of order a few million years, low luminosity radio sources are more likely to exhibit episodic behaviour in the accretion on to their supermassive black holes as compared to the more powerful radio galaxies.

scholarly journals AGN feedback on the ISM of 3C 236

2012 ◽  
Vol 8 (S292) ◽  
pp. 374-374
Author(s):  
A. Labiano ◽  
S. García-Burillo ◽  
F. Combes ◽  
A. Usero ◽  
R. Soria-Ruiz ◽  
...  
Keyword(s):  
Radio Galaxies ◽  
Molecular Gas ◽  
Evolutionary Status ◽  
Radio Sources ◽  
Powerful Radio ◽  
Ionized Gas ◽  
Normal Galaxies ◽  
Spatially Resolved ◽  
Formation Efficiency ◽  
Co Emission

AbstractWe have carried out 1mm/3mm continuum and 12CO(2−1) line high resolution observations to identify the footprints of AGN feedback on 3C 236. The CO emission comes from a spatially resolved disk characterized by a regular rotating pattern. Within the limits imposed by the sensitivity and velocity coverage of our data, we do not detect any outflow signatures in the cold molecular gas. Re-inspection of optical and IR spectra, shows the presence of a previously unknown ionized gas outflow. The star-formation efficiency in 3C 236, is consistent with the value measured in normal galaxies, which follow the canonical Kennicutt-Schmidt law. This result, confirmed to hold in other young radio sources examined in this work, is in stark contrast with the factor of 10–50 lower SFE that has been claimed to characterize evolved powerful radio galaxies. The recent reactivation of the AGN in 3C 236 is a likely explanation for the early evolutionary status of its molecular disk.

scholarly journals The Unification of Quasars and Radio Galaxies

1996 ◽  
Vol 175 ◽  
pp. 389-390 ◽  
Author(s):  
Sperello Di Serego Alighieri
Keyword(s):  
Radio Galaxies ◽  
Powerful Radio ◽  
Scattering Of Light ◽  
Recent Developments ◽  
Quasars And Radio Galaxies ◽  
Perpendicular Polarization

The evidence for misdirected quasars in the nuclei of powerful radio galaxies (PRG) is now solid: 1. strong perpendicular polarization of the UV continuum, produced by the scattering of light from the hidden nucleus, has been observed in 10 (out of 11) PRG with z > 0.7 (Cimatti et al. 1993); 2. polarized broad MgII2800 has been seen in 6 PRG (di Serego Alighieri et al. 1994, Antonucci et al. 1994), showing that the hidden nucleus is indeed a quasar. These findings are receiving authoritative confirmation from observations with the Keck telescope (Cimatti, Cohen and van Breugel in these Proceedings). Here I would like to concentrate on recent developments of our understanding of the unification between quasars and PRG.

scholarly journals Radio Galaxies and Quasars as Cosmological Probes

1996 ◽  
Vol 168 ◽  
pp. 71-78
Author(s):  
Ashok K. Singal
Keyword(s):  
Angular Size ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Powerful Radio ◽  
Extragalactic Radio Sources ◽  
Relativistic Beaming ◽  
Extended Radio ◽  
Statistical Sense ◽  
Cosmological Tests ◽  
The Universe

Various techniques and methods that have been developed for using extragalactic radio sources as cosmological probes of the universe are listed. The discussion is mainly confined to the cosmological tests employing extended radio sizes of powerful radio galaxies and quasars as standard metric rods (in a statistical sense) to figure out the geometry of the universe. Some comments are made on the recent use of the milliarcsec scale sizes of compact radio sources for angular size–redshift tests. It is further pointed out that the estimates of clustering for quasars selected at centimetre wavelengths could be seriously affected by the relativistic beaming.

scholarly journals Physical Conditions in CSS Radio Sources

2002 ◽  
Vol 199 ◽  
pp. 211-212
Author(s):  
S. A. Tyul'bashev ◽  
P. A. Tchernikov
Keyword(s):  
Phased Array ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Interplanetary Scintillation ◽  
Physical Conditions ◽  
Spectrum Radio ◽  
Quasars And Radio Galaxies

Interplanetary scintillation observations of 56 compact steep-spectrum radio sources have been carried out at 102 MHz on the Large Phased Array. Observations have shown that 42 sources have low frequency cut-offs in their spectra. The physical conditions in the compact components of the quasars and radio galaxies studied are estimated.

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