Radio Galaxies and Quasars in Clusters of Galaxies

1983 ◽  
Vol 5 (2) ◽  
pp. 144-151 ◽  
Author(s):  
J. Gordon Robertson
Keyword(s):  
Radio Galaxies ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Intracluster Medium ◽  
X Ray ◽  
Broad Field

The study of radio galaxies situated within clusters of galaxies has become a broad field, with hundreds of papers published in the last few years. This review will therefore be restricted mainly to consideration of the interactions between the extended components of radio sources in clusters and the diffuse gas (intracluster medium, ICM) which occurs in clusters. In particular, attention will be focused on what we can learn about the ICM from this interaction, in conjunction with other data such as X-ray observations. In the case of quasars in clusters of galaxies the emphasis is rather different, so discussion of this topic is deferred to section 6.

Steep-Spectrum Radio Sources in Clusters of Galaxies—The Southern Sample

1984 ◽  
Vol 5 (4) ◽  
pp. 516-529 ◽  
Author(s):  
O. B. Slee ◽  
J. E. Reynolds
Keyword(s):  
Radio Galaxies ◽  
High Energy ◽  
Radio Spectrum ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Detailed Review ◽  
X Ray ◽  
High Energy Electrons ◽  
Spectrum Radio ◽  
Inverse Compton

It is well established (e.g. Slee et al. 1983) that radio galaxies near the centres of rich clusters of galaxies tend to have steeper radio spectra than field radio galaxies. The fact that the sources with the steepest spectra occur in clusters that are highly luminous X-ray emitters has generally been interpreted in terms of the confining influence of a hot (~108 K), relatively dense (10-2 to 10-3 electrons cm-3) intra-cluster gas; the confined relativistic plasma then preferentially loses its high-energy electrons through synchrotron and inverse Compton losses, resulting in a steepening of the radio spectrum. A more detailed review of the evidence for this process is given by Robertson (1983).

scholarly journals The X-ray Intracluster Medium

1996 ◽  
Vol 175 ◽  
pp. 357-360
Author(s):  
H. Böhringer
Keyword(s):  
Equilibrium Configuration ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
X Rays ◽  
Intracluster Medium ◽  
Physical Processes ◽  
X Ray ◽  
Universal Expansion ◽  
Relativistic Particles ◽  
Galactic Radio

Clusters of galaxies are the largest aggregates of matter that have decoupled from the universal expansion and have approximately evolved to a proper dynamical equilibrium configuration. While in the optical they are just observed as dense concentrations of galaxies, they are seen in X-rays as continuously connected entities through the emission of the X-ray luminous intracluster plasma (e.g. Sarazin 1986). Relativistic particles and magnetic fields are observed in clusters in radio halos, in regions around radio galaxies and through Faraday rotation of the radiation from background radio sources (see contribution by L. Feretti and e.g. Kronberg, 1994). Thus Clusters of galaxies are the largest, well characterized astrophysical laboratories in which plasma physical processes of diffuse media can be studied. In this brief summary the bulk properties of the intracluster medium (ICM) are discussed and two studies of the interaction of galactic radio lobes with the intracluster plasma are presented (related topics are discussed by F. Owen and L. Feretti in this volume).

scholarly journals A2241: Clusters with Head-Tails at X-Rays

1996 ◽  
Vol 175 ◽  
pp. 361-362
Author(s):  
L. Norci ◽  
L. Feretti ◽  
E.J.A. Meurs
Keyword(s):  
Galaxy Cluster ◽  
Radio Galaxies ◽  
Brightness Distribution ◽  
Radio Sources ◽  
X Rays ◽  
Intracluster Medium ◽  
X Ray ◽  
Physical Conditions ◽  
The Galaxy ◽  
Energy Equipartition

A ROSAT PSPC image of the galaxy cluster Abell 2241 has been obtained, showing X-ray emission from the intracluster medium and from individual objects. The brightness distribution of the cluster gas is used to assess the physical conditions at the location of two tailed radio galaxies (in A2241E and A2241W, at different redshifts). Together with radio and X-ray information on the two galaxies themselves the results are of relevance to the question of energy equipartition in radio sources.

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 The Intergalactic Medium

1982 ◽  
Vol 97 ◽  
pp. 453-459
Author(s):  
A. C. Fabian ◽  
A. K. Kembhavi
Keyword(s):  
Radio Emission ◽  
Intergalactic Medium ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Intergalactic Gas ◽  
X Ray ◽  
Extended Radio ◽  
X Ray Background ◽  
Ngc 1275 ◽  
Intracluster Gas

The density of intergalactic gas may be an important parameter in the formation of extended radio sources. It may range from ∼ 0.1 particle cm−3 in the centres of some rich clusters of galaxies down to 10−8cm−3 or less in intercluster space. The possible influence of the intracluster gas surrounding NGC 1275 on its radio emission is discussed, and the possibility that a significant fraction of the X-ray background is due to a hot intergalactic medium is explored in some detail.

scholarly journals Observations of Straight-angle Tailed Radio Galaxies in Rich Clusters of Galaxies

1996 ◽  
Vol 175 ◽  
pp. 349-350
Author(s):  
Aileen A. O'Donoghue ◽  
Jean A. Eilek ◽  
Frazer N. Owen
Keyword(s):  
Spectral Index ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Data Set ◽  
Dynamical Properties

We have begun VLA observations of straight-angle tailed radio sources (SATs) at 1.5 and 4.8 GHz (L and C band) to achieve one arcsecond resolution at each frequency. This will provide a SAT data set similar to the O'Donoghue, Owen, and Eilek (1990) WAT data set with both total intensity and spectral index information. We will use these data to examine morphological and dynamical properties of straight-tailed radio sources in clusters of galaxies.

scholarly journals Theoretical Implications of Diffuse Non-Thermal Emission from Clusters of Galaxies

2002 ◽  
Vol 199 ◽  
pp. 141-148
Author(s):  
T.A. Enßlin
Keyword(s):  
Thermal Emission ◽  
Extreme Ultraviolet ◽  
Short Review ◽  
Radio Galaxies ◽  
High Energy ◽  
Clusters Of Galaxies ◽  
Thermal Electron ◽  
Electron Population ◽  
X Ray

A short review on theoretical implications of non-thermal emission (radio, extreme ultraviolet, high energy X-ray) from the intra-cluster medium is given. The origin of cluster radio halos and cluster radio relics is discussed within the framework of a network of processes producing a non-thermal electron population. Emphasis is given to the role of old, remnant, presently invisible relativistic plasma released by former radio galaxies.

scholarly journals Powerful Extended Radio Sources: A Goldmine for Cosmology

1996 ◽  
Vol 168 ◽  
pp. 469-472
Author(s):  
R. A. Daly
Keyword(s):  
Characteristic Length ◽  
High Redshift ◽  
Strong Shock ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Intracluster Medium ◽  
Radio Lobe ◽  
Extended Radio ◽  
Ambient Gas ◽  
Shock Jump

The radio properties of powerful extended radio sources may be used to study the environments of the sources, the source energetics, a characteristic length-scale that can be used as a cosmological tool, and the relation between radio galaxies and radio loud quasars. Thus, these sources offer a rich variety of diagnostics, both direct and indirect, of the cosmological model that describes our universe. They, indeed, are a goldmine for cosmology.Perhaps the most significant result of the investigations mentioned here is the use of the radio properties of the sources to estimate the ambient gas density in the vicinity of the radio lobe. As discussed below, the ambient gas densities estimated using the strong shock jump conditions across the radio lobe indicate that these sources lie in relatively dense gaseous environments, similar to the intracluster medium found in clusters of galaxies at low redshift. Thus, the observations suggest that at least some clusters with their intracluster medium in place exist at high redshift.

scholarly journals Radio Halos in Merging Clusters

2002 ◽  
Vol 12 ◽  
pp. 513-515 ◽  
Author(s):  
Gabriele Giovannini ◽  
Luigina Feretti
Keyword(s):  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Diffuse Source ◽  
X Ray ◽  
Diffuse Sources ◽  
Physical Conditions ◽  
Show Evidence ◽  
Radio Halos

AbstractThe number of known diffuse radio sources in clusters of galaxies (halos and relics) has grown in recent years, making it possible to derive statistical considerations on the physical conditions of these sources and on the properties of related clusters. We will discuss the percentage of clusters with a diffuse source and will show evidence that diffuse sources are associated with X-ray luminous clusters which have undergone recent merger processes.

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