The first detection of gravitational waves was made last year by the Laser Interferometer Gravitational-Wave Observatory, which picked up the distinctive vibration of two sun-sized black holes merging into a larger black hole. The waves, proposed by Albert Einstein more than 100 years ago, are similar to the ripples that form when a heavy rock is tossed into a pond.
Analysis of data collected by the Hubble and Chandra space telescopes and the Sloan Digital Sky Survey showed a bright quasar located far from its galaxy's core. Quasars are extremely bright, distant objects that are fueled by otherwise undetectable black holes.
"I was anticipating seeing a lot of merging galaxies, and I was expecting to see messy host galaxies around the quasars, but I wasn't really expecting to see a quasar that was clearly offset from the core of a regularly shaped galaxy," Chiaberge said. "Black holes reside in the center of galaxies, so it's unusual to see a quasar not in the center."
The astronomers found that the newly found black hole has traveled more than 35,000 light years from the center of its galaxy. It continues to zip away at a rate of some 4.7 million miles an hour.
At that speed, it could make the 240,000-mile trip between Earth and the moon in about three minutes. If the rate holds, the black hole will escape its host galaxy entirely in another 20 million years.
RELATED: Superbright Blazars Reveal Monster Black Holes Roamed the Early Universe
Chiaberge and his team theorize that the merger of two galaxies set the stage for the black hole's expulsion. They suggest that as two galaxies merged, their respective black holes settled into the center of a newly formed elliptical galaxy, creating ripples across spacetime known as gravitational waves.
The suspect the black holes were different sizes and were spinning at different rates, which caused the rippling of space to be stronger in one direction. When the two objects finally collided, the gravitational waves stopped, causing the newly created behemoth to recoil and shoot off in the opposite direction of the strongest waves.
"This asymmetry depends on properties such as the mass and the relative orientation of the back holes' rotation axes before the merger," Colin Norman, an astrophysicist with the Space Telescope Science Institute and Johns Hopkins University, said in a statement. "That's why these objects are so rare."
Future observatories may one day be able to detect gravitational waves from supermassive black hole mergers and other higher-energy phenomenon.
Photo: A runaway quasar fleeing from its galaxy's central hub. A quasar is the visible, energetic signature of a black hole. Black holes cannot be observed directly, but they are the energy source at the heart of quasars.