ALMA confirms close quasar pair

What ALMA found in merging galaxies

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have confirmed the existence of a close quasar pair. The quasars appear to be housed in two galaxies that are merging, based on observations of the interacting system.

Why this matters

Quasars—extremely bright regions powered by gas accreting onto supermassive black holes—are key signposts of black hole growth and galaxy evolution. When galaxies merge, their central black holes can sink toward each other, potentially forming a binary or close pair. Detecting a close quasar pair therefore provides a direct observational foothold for understanding how supermassive black holes move and eventually coalesce during galaxy mergers.

A confirmed close pair also helps constrain how frequently such systems occur and how long they remain observable at millimeter/submillimeter wavelengths. That, in turn, can inform models of merger-driven black-hole dynamics and the timing of active galactic nucleus activity.

What’s next

With ALMA confirming the pair, follow-up observations can focus on mapping the gas and dust environment of the merging galaxies—where the feeding material that powers the quasars resides—and on characterizing how the two black holes interact with their host systems. Systems like this offer one of the most promising pathways to link galaxy mergers to the formation and evolution of black-hole binaries.