Radio
Galaxies

Radio galaxies are usually elliptical. They often exhibit jet structure from a compact nucleus. They typically exhibit two lobes of radio frequency emission that are often approximately aligned with the jets observed in the visible spectrum and that may extend for millions of light years.

Examples of Radio Galaxies

The adjacent image shows a giant elliptical galaxy in the Virgo Cluster named NGC4261 that has gigantic radio frequency jets emerging from its nucleus (left side). The optical image is the white area in the center; the superposed radio lobes are in color. The right side shows a Hubble Space Telescope image of the central region of the galaxy where an enormous black hole is suspected to exist.

The giant elliptical galaxy M87 in the Virgo cluster is another example of a nearby radio galaxy. Here is a montage showing M87 surrounded by its globular clusters and showing a jet emanating from its nucleus. The optical jet of M87 is quite spectacular in this image, which is a composite constructed to enhance the jet relative to the rest of the galaxy (see this discussion).

Another spectacular example of a jet from an active galaxy is the "blowtorch" of the galaxy NGC6251 (see this discussion). Finally, here are images of jets from 4 radio galaxies with an explanation.

Examples of Radio Lobes for Active Galaxies

A montage of radio lobes associated with active galaxies is shown in the following figure (Source).

Generally, the optical counterparts for these radio lobes are very small compared with the extent of the radio lobes. For Fornax A the optical counterpart is about the size of the gap between the two lobes; for the other sources the optical counerparts are even smaller.


Next   Back   Top   Home   Help