Five gamma-ray blazars set new distance record

Bright galaxies in early universe suggest rapid growth of supermassive black holes

gamma-ray blazars

FAR OUT  Scientists have detected the five farthest gamma-ray blazars known. These bright galaxies, powered by supermassive black holes, were spotted using NASA’s Fermi Gamma-ray Space Telescope. Locations of the five blazars are marked on an image of the sky taken in gamma rays.

Scott Wiessinger/NASA’s Goddard Space Flight Center

WASHINGTON — Scientists have spotted a quintet of record-breaking blazars. The five gamma-ray blazars — supremely bright galaxies that host supermassive black holes — are the most distant ever spotted, at more than 11.7 billion light-years away.

As a gamma-ray blazar’s black hole swallows up matter, bright jets shoot out of the galaxy at close to the speed of light. If a jet happens to be pointed at Earth, the galaxy gleams brilliantly in the sky in the high-energy light of gamma rays.

Researchers spotted the far-flung blazars using NASA’s Fermi Gamma-ray Space Telescope, astronomer Roopesh Ojha of NASA’s Goddard Space Flight Center in Greenbelt, Md., reported January 30 at a meeting of the American Physical Society. The new blazars had whopper black holes, with the biggest weighing in at 7 billion times the mass of the sun.

The farthest blazar is so distant that the universe was just 1.4 billion years old at the time the light was emitted — only about a tenth of its current age. Blazars that shone so early in the universe pose puzzles for scientists who want to explain how the monster black holes formed.

“If you wait long enough, you can make a supermassive black hole,” says Ojha. “But the point here is that you haven’t had time.” To reach their enormous masses in just over a billion years, the blazars’ supermassive black holes must have gobbled up matter at a breakneck pace. How they did that is unknown.

Physics writer Emily Conover has a Ph.D. in physics from the University of Chicago. She is a two-time winner of the D.C. Science Writers’ Association Newsbrief award.

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