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Black Hole Gets Jerked Around - Twice
July 21, 2010

Radio galaxy 4C +00.58

This image shows the effects of a giant black hole that has been jerked around twice, causing its spin axis to point in a different direction from before. It shows a close-up view of a radio galaxy named 4C +00.58, where X-rays from the Chandra X-ray Observatory are shown in gold and radio waves from the Very Large Array are blue.

At the center of 4C +00.58 is a supermassive black hole that is actively pulling in large quantities of gas. Gas swirling toward the black hole forms a disk around the black hole, generating strong electromagnetic forces that propel some of the gas away from the disk at high speed, producing radio jets. A radio image of this galaxy shows a bright pair of jets pointing from left to right and a fainter, more distant line of radio emission running approximately from the top to the bottom of the image. The labels in the image shows these two sets of radio emission. This galaxy belongs to a class of "X-shaped" galaxies because of the outline of the radio emission.

The X-ray image of hot gas in and around 4C +00.58 reveals four different cavities - regions of lower than average X-ray emission - around the black hole. These cavities come in pairs: one in the top- right and bottom-left (labeled cavities #1 and #2 respectively), and another in the top-left and bottom-right (labeled cavities #3 and #4 respectively). Special processing was applied to this image to make the cavities more obvious.

According to the scenario presented by a new study, the spin axis of the black hole ran along a diagonal line from top-right to bottom- left. The galaxy then collided with a smaller galaxy. Possible evidence for this collision is seen in the optical image, in the form of a stellar shell. After this collision, a jet powered by the black hole ignited, blowing away gas to form cavities #1 and #2 in the hot gas. Since the gas falling onto the black hole was not aligned with the spin of the black hole, the spin axis of the black hole rapidly changed direction, and the jets then pointed in a roughly top-left to bottom-right direction, creating cavities #3 and #4 and radio emission in this direction.

Then, either a merging of the two central black holes from the colliding galaxies, or more gas falling onto the black hole caused the spin axis to jerk around to its present direction in roughly a left to right direction.

Credits: X-ray: NASA/CXC/UMD/Hodges-Kluck et al. Radio: NSF/AUI/NRAO/VLA/UMD/Hodges-Kluck et al.

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Page Editor: Brooke Boen