centre of our galaxy index: the radio window extragalactic radio sources

 Extragalactic radio sources


Fig. 1: Radio galaxy 3C219 glossary. Optical image (in blue) of the elliptical galaxy in the centre, with the radio emission (in red) coming out of it
(Credits: NRAO)		   90% of the radio sky is made up of distant elliptical galaxiesglossary and quasarsglossary, which emit an enormous quantity of energy in the radio wave range  by  synchroton process.

This energy, produced at the centre, in the nucleus of the elliptical galaxy, extends symetrically well beyond the galaxy itself, up to a distance of hundreds of thousands of light yearsglossary.

This morphology is quite typical for radio galaxies.

The figure on the right shows other examples of radio emissions in radio galaxies.

In all cases we can identify:

 

  • a compact nucleus coinciding with the center of the elliptical galaxy
  • one or two thin channels, called  jets,  through which we suppose the energy moves from the nucleus to the outskirts
  • lobes large-size external emission, where the energy of the relativistic particles is released in the form of radio waves.

     These characteristics are thought to be due to a massive black hole (approximately 106 solar masses) present in the galaxy centre

  
Fig. 2: Various examples of radio galaxies
(Credits: NRAO).

 
(Extragalactic radio sources- page 1 of 4)
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