scholarly journals A Radio Study of Abell Clusters

1977 ◽  
Vol 30 (4) ◽  
pp. 509 ◽  
Author(s):  
BY Mills ◽  
DG Hoskins
Keyword(s):  
Radio Source ◽  
Luminosity Function ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Multiple Sources ◽  
Radio Observatory ◽  
Cluster Membership ◽  
Abell Clusters

A search for radio sources close to 247 clusters of galaxies in the Abell catalogue has been carried out at the Molonglo Radio Observatory at a frequency of 408 MHz. A list of 116 sources near 89 clusters is given, identifications have been made and criteria for cluster membership have been established. A cluster luminosity function is derived in the range 1()23_1025 WHz-l SCi, and spectra have been obtained for sources in 25 clusters utilizing published surveys made at other frequencies. It is found that there is no correlation between the richness of a cluster and its inclusion of at least one radio source, but those clusters containing multiple sources are significantly richer than average.

scholarly journals Radio Sources in Clusters of Galaxies

1968 ◽  
Vol 21 (4) ◽  
pp. 511 ◽  
Author(s):  
BY Mills ◽  
RR Shobbrook ◽  
D Stewart-Richardson
Keyword(s):  
Radio Emission ◽  
Radio Source ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Cluster Galaxy ◽  
Stellar Objects ◽  
Cluster Emission ◽  
Cluster Galaxies ◽  
Individual Cluster

Fifty-eight clusters from Abell's catalogue have been examined for radio emission using the Arecibo l000 ft reflector and the Molonglo 1 mile Cross. The positions, sizes, and flux densities at 408 MHz of 30 radio sources close to these clusters have been measured. Nineteen of these offer reasonable identifications with galaxies or blue stellar objects. Thirteen appear to be identifiable with individual cluster galaxies. No evidence for integrated cluster emission has been obtained. It has been concluded that either the centroid of radio sources may sometimes be well displaced from the parent galaxies or, in a significant number of cases, the only detectable radio source in a cluster is associated with a faint cluster galaxy, not a giant.

scholarly journals Clusters of Galaxies and Radio Sources

1977 ◽  
Vol 74 ◽  
pp. 305-316 ◽  
Author(s):  
Walter Jaffe
Keyword(s):  
Luminosity Function ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Cluster Environment ◽  
Different Characteristics

For some time there have been suggestions that there is a special association of radio galaxies with rich clusters of galaxies, and more recently that the radio galaxies in clusters may show different characteristics from those outside. I will discuss the evidence for three types of such differences, in luminosity function, morphology, and occurance of steep spectrum sources. In each case I will try to connect any difference I find to the cluster environment.

scholarly journals Properties of Radio Sources in Clusters of Galaxies

1977 ◽  
Vol 4 (1) ◽  
pp. 321-328 ◽  
Author(s):  
Daniel E. Harris
Keyword(s):  
Radio Source ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Cluster A

“The properties of radio sources in clusters” presupposes that we know something about radio sources out of clusters, or that we even know whether a radio source is “in” or “out” of a cluster. Thus we are faced with the problem of defining what we mean by a cluster. Most of us use Abell’s catalogue of RICH clusters and assume that we are really “in” a cluster. However, most radio sources are identified with faint, distant objects and it is often difficult to know whether the remark “galaxy in a group” or “galaxy in a cluster” indicates a cluster such as the Coma Cluster, a cluster similar to an “open” Zwicky cluster, or a group of galaxies which may be gravitationally bound.This uncertainty must not be forgotten, and in the following discussion, we will try to limit the effects of this by concentrating on catalogued clusters; ignoring most distant radio galaxies, many of which may be in rich clusters; and also by neglecting quasars, some or all of which may be in clusters.

scholarly journals Radio Surveys and Large Scale Structure

1991 ◽  
Vol 44 (6) ◽  
pp. 759 ◽  
Author(s):  
PA Shaver
Keyword(s):  
Radio Source ◽  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Radio Galaxies ◽  
Scale Structure ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Normal Galaxies ◽  
Dimensional Distribution

An analysis of the Molonglo Reference Catalogue indicates that significant departures from isotropy are present in the sky distribution of strong extragalactic radio sources. This has been shown to be due to local large scale structure, specifically a concentration to the supergalactic plane, which also influences the slope of the source counts. A study of the three-dimensional distribution of local radio galaxies shows that they are more strongly concentrated to the supergalactic plane than are optically�selected galaxies, and that the supergalactic concentration is more extensive than hitherto believed. It appears that radio galaxies (and clusters of galaxies) trace the 'skeleton' of large scale structure, about which normal galaxies are more loosely distributed. Thus, while large scale structure evidently complicates the interpretation of radio source counts, it appears that radiO surveys can be of value in exploring structures on the largest scales.

Radio Observations of Clusters of Galaxies

1967 ◽  
Vol 1 (1) ◽  
pp. 24-24
Author(s):  
B. Y. Mills ◽  
R. R. Shobbrook
Keyword(s):  
High Resolution ◽  
Luminosity Function ◽  
Radio Galaxies ◽  
Detailed Examination ◽  
Statistical Information ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Radio Observations ◽  
Radio Frequencies

High resolution studies of clusters of galaxies at radio frequencies may contribute substantially to our knowledge of the properties of radio galaxies, their evolution and their luminosity function. A considerable amount of statistical information is already available on the correspondence of radio sources and clusters; the present investigation is aimed rather at a detailed examination of the sources and their identification with actual galaxies or other objects.

Interplanetary Scintillation Studies at the Molonglo Radio Observatory

1972 ◽  
Vol 2 (2) ◽  
pp. 88-89
Author(s):  
R. G. Milne
Keyword(s):  
Radio Source ◽  
Radio Telescope ◽  
Interplanetary Medium ◽  
Small Diameter ◽  
Line Of Sight ◽  
Radio Sources ◽  
The Sun ◽  
Interplanetary Scintillation ◽  
Radio Observatory ◽  
Half Power

The structure of small diameter radio sources can be investigated by studying the scintillation of the source due to the interplanetary medium when the line of sight approaches the Sun. Observations of radio source scintillation are currently being undertaken with the separate arms of the 1 mile radio telescope at the Molonglo Observatory. The EW arm allows successive transit observations with three fan beams, 1′.4 EW by 4°.2 NS at 408 MHz, bandwidth 2.5 MHz. Sources transit the half-power points of each beam in 6 sec δ seconds of time (δ is the source declination). The NS arm gives eleven fan beams at neighbouring declination, 1′.5 sec Z NS by 4° EW (Z is the zenith angle). Complete transit of a NS beam takes 15 sec δ minutes.

scholarly journals Evolution of the Cluster X-Ray Luminosity Function

1980 ◽  
Vol 92 ◽  
pp. 231-231
Author(s):  
Stephen C. Perrenod
Keyword(s):  
Power Law ◽  
Luminosity Function ◽  
Mass Function ◽  
Mass Relation ◽  
Clusters Of Galaxies ◽  
Supply Rate ◽  
X Ray ◽  
Abell Clusters ◽  
Number Counts ◽  
Gas Supply

I predict the evolution of the X-ray luminosity function of clusters of galaxies. Predominantly, I treat the assumption that galaxies form first, then cluster purely due to gravitation. I show that the richness distribution of Abell clusters favors this scenario, rather than the protocluster hypothesis. The luminosity function is produced by combining a generalized (for all Ω) Press-Schechter evolutionary mass function for clusters (derived herein) with a power law X-ray luminosity-mass relation; a power law relation is supported by observations of low-redshift clusters.I find very steep evolution in the luminosity function, and thus in the source counts, for large Ω, and moderate evolution for small Ω. For a variety of models for the gas supply rate to the intracluster medium, the evolution of the luminosity function does not vary greatly. Thus it appears that the Ω, dependence will dominate and that number counts of X-ray clusters will yield cosmological information. The power of a test of Ω with an evolving luminosity function is considerably enhanced relative to a test which involves solely global cosmological effects on a non-evolving population. This occurs because of the well-known result that, at late times, clustering tends to proceed slowly for universes of small Ω and rapidly for large Ω.

Powerful Radio Sources in Clusters of Galaxies

1991 ◽  
Vol 9 (1) ◽  
pp. 100-102
Author(s):  
A. M. Unewisse ◽  
R. W. Hunstead
Keyword(s):  
Radio Emission ◽  
Radio Source ◽  
Flux Density ◽  
Radio Sources ◽  
High Flux ◽  
Clusters Of Galaxies ◽  
Powerful Radio ◽  
Complete Sample ◽  
Cluster Galaxies ◽  
Cluster Centre

AbstractUsing a complete sample, we have looked for correlations in position between radio sources with S408 ≥ 1 Jy in the Molonglo Reference Catalogue (MRC) and rich clusters of galaxies in the Abell, Corwin and Olowin catalogue (ACO). Within a projected radius of 100 kpc of the cluster centre, we find an overdensity of radio sources similar to that seen by Robertson and Roach (1990). They attributed this feature to centrally located dominant cluster galaxies. We confirm this hypothesis by looking at the morphology of the clusters within this peak and by optically identifying galaxies associated with the radio emission. Due to the relatively high flux density limit imposed, the cluster radio sources in this sample are among the most powerful in the southern sky. The probability of a cluster containing a radio source of this power is found not to depend on cluster richness.

Radio Sources with Wide-Angle Tails in Abell Clusters of Galaxies

1976 ◽  
Vol 205 ◽  
pp. L1 ◽  
Author(s):  
Frazer N. Owen ◽  
Lawrence Rudnick
Keyword(s):  
Radio Sources ◽  
Wide Angle ◽  
Clusters Of Galaxies ◽  
Abell Clusters
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