Astronomers have detected two active black holes merging at the farthest distance, just 900 million years after the Big Bang. This is the first time two bright supermassive black holes have been seen during the cosmic dawn.

The Cosmic Dawn is the time spanning the first billion years of the universe’s existence. During this period, about 400 million years after the Big Bang, the Epoch of Reionization began, when light from newborn stars stripped hydrogen of its electrons, causing a fundamental change in the structure of galaxies.

“The existence of quasars merging during the reionization period has long been predicted.” stated that The study’s lead author, Yoshiki Matsuoka, is an astronomer at Ehime University in Japan. “This is the first time this has been confirmed.”

Researchers published their findings on April 5 Astrophysics Journal Letters.

Black holes arise from the collapse of giant stars and grow by continually absorbing gas, dust, stars, and other black holes from the star-forming galaxies that contain them. If they grow large enough, friction causes material to heat as it spirals toward the mouth of the black hole, and they become quasars, shedding cocoons of gas in bursts of light trillions of times brighter than the brightest stars.

Since light travels at a constant speed through the vacuum of space, the deeper scientists look into the universe, the further away they capture light and the further back in time they see.

Previous simulations of the cosmic dawn have shown that billowing clouds of cold gas can coalesce into massive stars doomed to rapidly collapse and form black holes. As the universe grew, these early black holes may have rapidly merged with others, creating even larger supermassive black holes in the universe.

Approximately 300 quasars have been found during the reionization period, but these newly discovered quasars are the first to be detected as a pair. Researchers found them using the Subaru Telescope’s Hyper Suprime-Cam; this camera showed them as two faint red dots in the middle of a background of bright galaxies and stars.

Astronomers then performed spectroscopic imaging and confirmed that the source of the light was a double spiral quasar. The researchers say their discovery will help them understand how powerful light beams from quasars shape the structure of the universe we see today.

“The statistical properties of reionization-era quasars tell us many things, such as the progression and origin of reionization, the formation of supermassive black holes during the cosmic stellar sequence, and the earliest evolution of quasar host galaxies,” Matsuoka said.