Astronomers have used a pair of Mauna Kea telescopes to shed light on one of the universe’s earliest stages of development.

Using the Gemini North and Subaru telescopes, a team led by astronomer Yoshiki Matsuoka at Ehime University in Matsuyama, Japan, peered billions of years into the past by detecting the light of a pair of quasars merging only 900 million years after the big bang.

Quasars are extremely bright — shining with light thousands of times greater than that of an entire galaxy — celestial objects composed of a supermassive black hole surrounded by a vast amount of superheated gas. The two detected by Matsuoka’s team each have black holes more than 100 million times the mass of our sun.

Not only are the two quasars the oldest and most distant such objects observed so far, they are the first quasars to be seen merging together. That discovery, particularly at such an early stage in the universe’s life, supports astronomers’ theories about how the universe has evolved, Matsuoka told the Hawaii Tribune-Herald.

Matsuoka said via email that the standard theory of cosmology posits that the universe evolved into its present state via frequent mergers of supermassive objects like galaxies during its early stages.

The merger took place during a period of transition in the universe, from a period called the “Cosmic Dawn” when the first stars and galaxies were formed, to a more energetic state where massive celestial objects could form more frequently. The precise cause of that transition is still a matter of significant astronomical inquiry.

“This pair is a precious laboratory of physical processes that will accompany quasar mergers,” wrote Matsuoka, adding that his teams’ observations suggest that the merger of the two objects has caused “spectacular” gas structures surrounding them, which themselves have implications on star formation in the early universe.

While quasars are extremely brilliant objects, Matsuoka said the two were so far away as to be barely detectable — only because of very sensitive instruments at Subaru were they discovered at all. After their discovery a second observation pass at the objects with Gemini was unable to detect them at all — which itself allowed astronomers to conclude that the merger had led to the formation of stars.