"We also looked a bit farther in the universe so that we could survey a larger volume of space, giving us a greater chance of finding more luminous, rapidly-growing black holes". If there are pairs of black holes, they will likely merge within the next 10 million years to form a more massive black hole. Astronomers have observed several pairs of galaxies in the final stages of merging after colliding.
Peering through thick walls of gas and dust surrounding the merging galaxies' messy cores, the research team captured pairs of supermassive black holes - each of which once occupied the center of one of the two original smaller galaxies - drawing closer together before they coalescence into one giant black hole.
"Seeing the pairs of merging galaxy nuclei associated with these huge black holes so close together was pretty awesome", Koss said in a statement. Keck Observatory pioneered the astronomical use of both natural guide star (NGS) and laser guide star adaptive optics (LGS AO) on large telescopes and current systems now deliver images three to four times sharper than the Hubble Space Telescope.
The images also provide a close-up preview of a phenomenon that must have been more common in the early universe, when galaxy mergers were more frequent.
As two galaxies finally merge, their black holes emit gravitational waves, which are a form of powerful energy that causes ripples in space-time.
In about 6 billion years, scientists estimate that the Milky Way will merge with the Andromeda galaxy into one big galaxy.
We're just beginning to imagine the titanic forces involved when two galactic cores and their supermassive black holes merge like in this simulation.
Dr Koss and his team of scientists first looked for hidden black holes by searching through 10 years' worth of X-ray data from NASA's Neil Gehrels Swift Observatory.
The researchers analyzed 96 galaxies observed at Keck Observatory, and 385 of galaxies from the archive of Hubble.
Keck was then called on to use its near-infrared vision to observe the x-ray producing black holes not found in the Hubble archive.
A team of researchers led by Michael Koss of Eureka Scientific Inc., in Kirkland, Washington, performed the largest survey of the cores of nearby galaxies in near-infrared light, using high-resolution images taken by NASA's Hubble Space Telescope and the W. M. Keck Observatory in Hawaii.
The researchers found that more than 17 percent of these galaxies hosted a pair of black holes at their centers, signs of the late stages of a galactic merger. They published the results in the journal Nature on November 8. Galactic mergers could give supermassive black holes the opportunity to rip apart stars and devour matter, releasing extraordinary amounts of light.
That research suggested that black holes at the cores of colliding galaxies may combine to become even larger black holes. In approximately six billion years the process will be complete and a single elliptical galaxy will be born.
Various colliding galaxies along with closeup views of their coalescing nuclei in the bright cores. "Simulations reveal that galaxies kick up plenty of gas and dust as they undergo this slow-motion train wreck".
When the two supermassive black holes in each of these systems finally come together in millions of years, their encounters will produce strong gravitational waves.
The team targeted galaxies located an average of 330 million light-years from Earth - relatively close by in cosmic terms.
Scientists believe a similar event will occur when our Milky Way galaxy collides with the Andromeda galaxy. Gravitational wave detectors tell astronomers what area, and Koss' research tells them whether that object is likely to host a supermassive black hole merger. The data presented herein were obtained at Keck Observatory, which is a private 501 (c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The findings shed light on how even more-massive black holes might come about.