Centaurus A
The center of the galaxy has a supermassive black hole. Its mass is about 55 million solar masses. This ejects a relativistic jet with emissions in the X-ray and radio wavelengths. Astronomers have taken radio observations of the jet ten years apart. They found that the inner parts of the jet are moving at about half the speed of light. X-rays are produced further out as the jet collides with surrounding gas. This produces highly energetic particles. The radio jets of Centaurus A are over a million light years long.