Results 221 to 230 of about 38,529 (262)

Models for Extragalactic Radio Sources

Symposium - International Astronomical Union, 1986
Doubt is cast on the reality of the following four assumptions commonly made in the treatment of extragalactic radio sources: (1) The central engine is a black hole; (2) Electrons can be accelerated in situ in the knots and heads of the jets, to large Lorentz factors γ ≥ 102, with an efficiency exceeding 30%; (3) The (non-thermal) radiation emitted by ...
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Jets in Extragalactic Radio Sources

Science, 1984
Observations now require that there be a continuous supply of energy to the giant extragalactic radio sources. These observations also suggest that this energy input may be in the form of streams or jets of gas emanating from the centers of galaxies and quasi-stellar objects. Current data indicate that the large-scale jet structures are not moving with
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Extended Extragalactic Radio Sources

Annual Review of Astronomy and Astrophysics, 1976
The most important feature of the extended sources is the double structure characterized in an ideal model by two extended radio-emitting regions situated symmetrically about the nucleus of an optical galaxy or QSO, with a characteristic overall size of about 100 kpc. Not all extended radio sources show this double structure. It has been found that at
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Theory of extragalactic radio sources

Reviews of Modern Physics, 1984
Powerful extragalactic radio sources comprise two extended regions containing magnetic field and synchrotron-emitting relativistic electrons, each linked by a jet to a central compact radio source located in the nucleus of the associated galaxy. These jets are collimated streams of plasma that emerge from the nucleus in opposite directions, along which
Mitchell C. Begelman, Roger D. Blandford, Martin J. Rees   +2 more
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Surveys of extragalactic radio sources

EAS Publications Series, 2005
Nearly all discrete radio sources are extragalactic and lie at cosmological distances. Most sources stronger than ~1 mJy at 1.4 GHz are powered by active galactic nuclei (AGNs), while the majority of fainter sources are in starburst galaxies. Recent all-sky surveys have detected most of this AGN population, and smaller surveys are now sensitive enough ...
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Modelling Extended Extragalactic Radio Sources

Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics, 2000
Abstract This paper examines the process of modelling a complex empirical phenomenon in modern astrophysics: extended extragalactic radio sources. I show that modelling is done piecemeal, addressing selected striking or puzzling features of that phenomenon separately and individually.
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Polarization properties of extragalactic radio sources

Astrophysics and Space Science, 1979
In order to give a good description of the polarization properties of extragalactic radio sources together with some other radio and optical data for these sources, all published polarization observations of extragalactic radio sources from 1965 to the middle of 1974 have been collected.
W. Eichendorf, M. Reinhardt
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Rapid variability of extragalactic radio sources

Nature, 1989
Since its discovery more than 20 years ago1,2, variability of extragalactic radio sources on timescales of weeks to years has been the subject of many investigations. Little is known, however, about radio variability of extragalactic sources on timescales of less than a few days.
A. Quirrenbach, A. Witzel, T. Krichbaum, C. A. Hummel, A. Alberdi, C. Schalinski   +5 more
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Jets in extragalactic radio sources

AIP Conference Proceedings, 1979
Particle acceleration in the extended parts of radio galaxies seems likely from a number of arguments. The radio jets which now seem commonly to connect the nucleus to the more extended structure of radio galaxies are a likely location for some of the necessary in situ acceleration.
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Evolution of Extragalactic Radio Sources

EAS Publications Series, 2001
I review the current paradigm for extragalactic radio sources including their classification, relationship to their host galaxies, their environments, their propagation, and their lifetimes. I emphasize recent progress in our understanding of radio source evolution and I discuss the current open questions.
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