Fig13_7 The radio galaxy Cygnus A

Fig13_7 The radio galaxy Cygnus A

Fig. 13.7 . The radio galaxy Cygnus A, listed as 3C 405 in the third Cambridge catalogue of bright radio sources, which has a radio output a million times more powerful than the radio emission of a normal galaxy like the Milky Way. This radio image, taken with the Very Large Array at a wavelength of 6 cm with a field of view of 0.038 x 0.022 degrees, shows two narrow, straight radio-emitting jets of particles that protrude in opposite directions from a giant elliptical galaxy at the center. The redshift of the optically visible elliptical indicates a distance of about 780 million light-years, and a linear extent for the radio galaxy of about a million light-years from end to end. The radio jets have probably been ejected along the rotation axis of a super-massive black hole located within a central elliptical galaxy. It must have been active for tens of millions of years to produce the two radio lobes. (Courtesy of NRAO/AUI/NSF.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University