3C438: A central galaxy in the center of a massive cluster of galaxies, 4.8 billion light years away.
Caption: This comparison of 3C438 in optical (left) and X-ray (right) light reveals evidence for one of the most energetic events in the local Universe. An arc-like feature to the lower left in the cluster's hot gas is about 2 million light years long. Astronomers have determined that an enormous amount of energy would be required to produce such a large structure. One plausible scenario is that two massive clusters collided at high velocity and later merged. Another intriguing feature in the Chandra data is the possible detection of a cavity in the hot gas, which may be the result from a tremendous outburst from a supermassive black hole.
Scale: Each panel is 8 arcmin per side.
Chandra X-ray Observatory ACIS Image