Elliptical Galaxies—Getting to the Heart

1990 ◽  
Vol 8 (3) ◽  
pp. 238-242
Author(s):  
Elaine M. Sadler
Keyword(s):  
Optical Properties ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Radio Sources ◽  
Powerful Radio

AbstractElliptical galaxies are at first sight a remarkably homogenous class of objects, yet some of them produce large and enormously powerful radio sources while others remain more or less quiescent. Why should this be so? What prompts the nucleus of an elliptical galaxy to become ‘active’? What, if anything, do elliptical galaxies have in common with the bulges of spirals? Here, I review some of the radio and optical properties of nearby elliptical galaxies, with special emphasis on events which take place within the central kiloparsec.

scholarly journals PRONGS: Powerful Radio Objects Nested in Galaxies with Star Formation

2009 ◽  
Vol 5 (S267) ◽  
pp. 119-119
Author(s):  
Minnie Y. Mao ◽  
Ray P. Norris ◽  
Rob Sharp ◽  
Jim E. J. Lovell
Keyword(s):  
Optical Properties ◽  
Star Formation ◽  
Elliptical Galaxies ◽  
Radio Sources ◽  
Powerful Radio ◽  
Local Universe ◽  
Star Forming ◽  
New Class

AbstractWe have identified a new class of object that we term PRONGS (powerful radio objects nested in galaxies with star formation). These are powerful radio sources whose optical properties are that of spiral/star-forming galaxies, unlike classic powerful radio sources which are typically hosted by elliptical galaxies in the local Universe. Here we present a first look at these enigmatic sources.

scholarly journals Radio Source Environments at Redshifts > 0.5

1996 ◽  
Vol 175 ◽  
pp. 321-322
Author(s):  
M. Lacy ◽  
S. Rawlings ◽  
M. Wold ◽  
A. Bunker ◽  
K.M. Blundell ◽  
...  
Keyword(s):  
Radio Source ◽  
High Redshift ◽  
Elliptical Galaxies ◽  
Radio Sources ◽  
Powerful Radio ◽  
Host Galaxies ◽  
Local Universe ◽  
Wide Range ◽  
Age Of The Universe ◽  
The Universe

The most powerful radio sources in the local Universe are found in giant elliptical galaxies. Looking back to a redshift of 0.5 (≈ half the age of the Universe for ω = 1), we see that these host galaxies are increasingly found in moderately rich clusters. This fact gives us hope that radio sources can be used as tracers of high density environments at high redshift. By exploiting radio source samples selected over a wide range in luminosity (Blundell et al., these proceedings), we will also be able to test whether the luminosities of radio sources are correlated with their environments.

scholarly journals Feedback and environmental effects in elliptical galaxies

2009 ◽  
Vol 5 (H15) ◽  
pp. 289-290
Author(s):  
Craig L. Sarazin
Keyword(s):  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Energy Output ◽  
Radio Sources ◽  
Early Type ◽  
Gas Stripping ◽  
Interstellar Gas ◽  
X Ray ◽  
Radio Jets

AbstractThe role of the environment of an elliptical galaxy on its hot interstellar gas is discussed. In general, the X-ray halos of early-type galaxies tend to be smaller and fainter in denser environments, with the exception of group-central galaxies. X-ray observations show many examples of nearby galaxies which are undergoing gas stripping. On the other hand, most bright galaxies in clusters do manage to retain small coronae of X-ray emission. Recent theoretical and observational results on the role of feedback from AGN at the centers of elliptical galaxies on their interstellar gas are reviewed. X-ray observations show many examples of X-ray holes in the central regions of brightest-cluster galaxies; in many cases, the X-ray holes are filled with radio lobes. Similar radio bubbles are seen in groups and individual early-type galaxies. “Ghost bubbles” are often seen at larger radii in clusters and galaxies; these bubbles are faint in high radio frequencies, and are believed to be old radio bubbles which have risen buoyantly in the hot gas. Low frequency radio observations show that many of the ghost bubbles have radio emission; in general, these long wavelength observations show that radio sources are much larger and involve greater energies than had been previously thought. The radio bubbles can be used to estimate the total energy output of the radio jets. The total energies deposited by radio jets exceed the losses from the gas due to radiative cooling, indicating that radio sources are energetically capable of heating the cooling core gas and preventing rapid cooling.

A Radio Continuum Survey of Southern E and SO Galaxies at 2.7 GHz and 5.0 GHz

1982 ◽  
Vol 4 (4) ◽  
pp. 454-456
Author(s):  
E. M. Sadler
Keyword(s):  
Radio Emission ◽  
Radio Source ◽  
External Factor ◽  
Elliptical Galaxies ◽  
Radio Continuum ◽  
Radio Sources ◽  
Gravitational Perturbation ◽  
Early Type ◽  
Powerful Radio ◽  
Central Source

The reason why some early-type galaxies contain powerful radio sources is not yet well understood, but it is often suggested that an external factor such as interaction with a neighbouring galaxy may be involved in triggering a radio source (Gisler 1976, Dressel 1981, Hummel 1981b). Radio emission may be enhanced in galaxies which have a close companion for several reasons, such as a gravitational perturbation or the possibility of gas accreted from the companion fuelling a central source. The latter effect might be expected to be more pronounced in elliptical galaxies, which are generally gas-poor (Faber and Gallagher 1976).

scholarly journals Active Nuclei and Redshift Problems

1983 ◽  
Vol 6 ◽  
pp. 531-533
Author(s):  
Geoffrey Burbidge
Keyword(s):  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Radio Sources ◽  
Powerful Radio ◽  
Radiation Mechanism ◽  
X Ray ◽  
Major Interest ◽  
Relativistic Particles

More than 20 years ago V. A. Ambartsumian proposed that much of the activity in galaxies was dominated and even generated by their nuclei. Subsequent observational work in radio, optical and x-ray frequencies has borne out his prophecy, and major interest has centered about the nature of the machine in the galactic nucleus. The major characteristic of this machine is that it releases energy rapidly and often spasmodically by processes which are not thermonuclear in origin.The original studies which led to the conclusion that nuclei were all important were observations of the powerful radio sources and Seyfert galaxies, and evidence for the ejection of gas from galaxies of many types. The realization that the synchrotron mechanism was the dominant radiation mechanism and the later studies of Compton radiation were fundamental in leading to the conclusion that large fluxes of relativistic particles must be generated in galactic nuclei.

scholarly journals The Nature of Faint Radio Sources

1986 ◽  
Vol 7 ◽  
pp. 345-353
Author(s):  
J V Wall ◽  
C R Benn ◽  
G Grueff ◽  
M Vigotti
Keyword(s):  
Elliptical Galaxies ◽  
Aperture Synthesis ◽  
Radio Sources ◽  
Mixed Group ◽  
Blue Galaxies ◽  
Infrared Data

AbstractRadio, optical and infrared data are combined to study the nature of mJy-sources found in the 5C12 aperture-synthesis survey. The optical counterparts are QSOs, giant elliptical galaxies of the 3CR type, and blue galaxies. We find that the blue galaxies are a mixed group; the suggestion of a new blue population of evolving spirals at mJy levels is not supported by our data.

Tables of physical and morphological properties of nearby extended radio galaxies

2021 ◽  
pp. 75-89
Author(s):  
R. R. Andreasyan ◽  
H. V. Abrahamyan
Keyword(s):  
Radio Galaxies ◽  
Elliptical Galaxies ◽  
Morphological Data ◽  
Morphological Properties ◽  
Radio Sources ◽  
Extragalactic Radio Sources ◽  
Extended Radio

It is brought the physical and morphological data of 267 nearby radio galaxies identified with elliptical galaxies brighter than 18th magnitude (sample 1) and for 280 extragalactic radio sources with known position angles between the integrated intrinsic radio polarization and radio axes (sample 2).

scholarly journals Relations Between the Optical and Radio Properties of Extragalactic Radio Sources

1977 ◽  
Vol 74 ◽  
pp. 223-235
Author(s):  
E. M. Burbidge
Keyword(s):  
Optical Properties ◽  
Physical Theory ◽  
Radio Sources ◽  
Intrinsic Properties ◽  
Extragalactic Radio Sources ◽  
Nonthermal Radiation ◽  
The Universe

Correlations between the radio and optical properties of radio sources have proved elusive and the main conclusion to be drawn from this is that there is a great variety of objects in the universe that emit nonthermal radiation, so that attempts to use these objects for cosmological purposes can be frustrated unless one can find some way of selecting objects that do have common intrinsic properties. Despite this, the search for relations and correlations is interesting quite apart from cosmology, because such correlations should provide a groundwork for a physical theory or theories of what is really happening in sources of nonthermal radiation.

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