Active galactic nuclei are periods when supermassive black holes at the center of galaxies accrete surrounding matter and gas and emit intense radiation. Our own Milky Way hosts a supermassive black hole at its center, but it is currently in a quiescent state.

Previous research suggested that galaxy mergers might help drive the formation and evolution of supermassive black holes. The new Euclid data, published in a special edition of Astronomy and Astrophysics, provide the strongest evidence so far that mergers play a key role. Scientists, including University of British Columbia researcher Dr. Allison Man, used artificial intelligence to examine hundreds of thousands of galaxy mergers stretching back up to 10 billion years.

The team reports that active galactic nuclei occur two to six times more often in merging galaxies than in comparable systems that are not merging. The association is especially strong for active galactic nuclei heavily obscured by dust, which are linked to rapid black hole growth as material falls into the central object. These dust-enshrouded nuclei are also the most luminous, outshining their host galaxies.

Other, less luminous supermassive black holes at galactic centers likely grow through different mechanisms, according to the authors. "We're starting to explore just how supermassive black holes form and evolve, and to pin down the connection between galaxy mergers, supermassive black hole mergers and how they contribute to building up the most massive black holes in the universe," said Dr. Man.

Data Release:Euclid Quick Data Release (Q1)

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