Astronomers Todd Boroson and Tod Lauer have found what appears to be the best candidate seen for a tightly bound binary black hole, a close-knit duo of death in the center of a quasar. They sifted through over 17,000 quasar signatures to find this rare pair, sitting in the center of quasar SDSS 153636.22+044127.0 at a distance of about 4 billion light years from Earth.
Although many double black holes are known (for example, NGC 6240 and 3C 75) -- remnants of ancient galactic mergers, two galaxies colliding and eventually forming a single, bigger galaxy -- these are widely-spaced pairs (30,000 and 10,000 light years apart, respectively, for NGC 6240 and 3C 75), and while it's likely that in those cases the black holes orbit each other, it's not completely certain. In this new case, while it's still not 100% rock-solid certain the two holes orbit one another, it's very, ...
