The record-breaking duo appear to have starved themselves to a standstill
A pair of supermassive black holes that have been trapped dancing around each other for billions of years have now been found to be the heaviest binary ever measured. Though theory predicts that such pairs of supermassive black holes should merge together, the act of merging has never actually been seen. The huge mass of this pair could help astronomers understand why such mergers are seemingly so rare.
The pair are located in B2 0402+379, an enormous ‘fossil cluster’ galaxy created when an entire cluster’s worth of galaxies and stars merged into a single giant elliptical. Most galaxies host a central supermassive black hole. When galaxies merge, these begin orbiting around one another. As they circle, they transfer some of their energy to the surrounding stars and gas – much of which is ejected in the process. The more energy these black holes lose to the material around them, the closer they move towards each other.
In the case of this binary pair, the black holes moved in until they were a mere 24 lightyears apart – the smallest such separation ever directly measured. However, they have remained stuck at this distance for the last three billion years. To understand why this might be the case, astronomers have used the Gemini North telescope’s Gemini Multi-Object Spectrograph (GMOS) to study the system.
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