JWST reveals closest pair of black holes in early universe

Astronomers have discovered the closest-together pair of actively feeding supermassive black holes ever confirmed in the early universe, separated by just 4,900 light-years inside a merging galaxy system observed as it existed only 1.3 billion years after the Big Bang. The discovery, made using the James Webb Space Telescope and the Atacama Large Millimeter/submillimeter Array in Chile, has been accepted for publication in Nature Astronomy.livescience

The system, known as LID-1166, was first detected as an X-ray source in the Chandra COSMOS Legacy Survey but remained invisible in even the deepest Hubble Space Telescope images. JWST's Near-Infrared Spectrograph revealed two compact, glowing sources whose spectral signatures indicated gas swirling at high speeds — the hallmark of actively feeding black holes.livescience

Breaking Through Cosmic Dust

"This step of the discovery could happen only thanks to the exquisite imaging and spectroscopic capabilities of the JWST, and in particular its instrument NIRSpec," said study co-author Roberto Decarli, an astronomer at the Italian National Institute for Astrophysics in Bologna. "Similar observations from the ground would be extremely challenging due to the poor transparency of the atmosphere at these wavelengths."livescience

While other dual black hole candidates have been spotted at even earlier cosmic times, those pairs were separated by tens of thousands of light-years or more. LID-1166 represents the first confirmed case of two black holes existing this close together at such an early epoch.livescience

ALMA data further revealed large pools of cold gas associated with each black hole, pointing to two galaxies on the verge of merging — and ruling out scenarios in which one black hole had been ejected from its host galaxy.livescience

A Wave of Early Universe Black Hole Discoveries

The finding arrives alongside a separate study published this week in Astronomy & Astrophysics, which reported the first detection of three active supermassive black holes within a single galaxy. That system, J0148-4214, is even more distant at 12.5 billion light-years and contains two central black holes separated by only 620 light-years, plus a third located 5,500 light-years from the center.dailygalaxy+2

Together, these discoveries suggest that galaxy mergers were already driving black hole growth and pairing in the universe's first billion years — a process long predicted by theory but only now being observed directly.

"What is striking here is resolving this process in an obscured pair that is only 1.5 kiloparsecs apart," said Anna Trindade Falcão, an astrophysicist at NASA's Goddard Space Flight Center who was not involved in the LID-1166 study. This, she added, "is the first step toward uncovering a hidden population of black holes that, in theory, we know should exist."livescience