The jets of some radio sources show a wavy jet structure, almost as if the ejection occurred out of a hose, which was being swung around in a circle. It is believed that this is precisely what would be expected if the black hole is precessing, that is, if its axis is slowly wobbling about its average direction in space. A black hole may precess because of a gravitational pull from another object, perhaps another black hole, a galaxy, or a dead quasar passing close by. The flailing jets of 3C 75 (Figure 10.3) may be caused by the precession of a disk surrounding two interacting black holes. The precession is extremely slow and takes many millions of years to complete one wobble.
Was this article helpful?