But one quasar in the survey displayed two distinct sets of energy emissions moving at different speeds. The astronomers interpreted this to be two black holes spinning around each other.
According to Einstein's theory, such a system might be producing an effect called gravitational radiation, noted Jon Miller of the University of Michigan in Ann Arbor. Miller was unaffiliated with the research but reviewed it for publication in this week's issue of the journal Nature.
Although cosmologists have yet to see the effect directly, they think gravitational radiation propagates across the universe like waves on the surface of a puddle and remains unchanged as it travels.
Because the ripples reach us in an unaltered state, their strength, direction, and frequency could tell us more about the distant, dramatic events that created them, such as supernovae and black hole mergers.
Study author Boroson added that this particular pair of black holes may be in a key phase of a union.
Theoretically, gravitational interaction with stars and gases will help push two nearby black holes closer together.
But at a certain point there may be nothing left for the black holes to interact with, because they will have swallowed or thrown out all nearby matter. Then they become stuck in close orbit until something gives them a nudge.
The black holes in question now seem to be close enough to have gotten at least partially past this sticking point, Boroson said.
According to the researcher, the "endgame story" of black hole pairs like this one is to merge into a single massive object.
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