The black holes sink to the centre of the cluster, where a core that is completely made of up of black holes forms.
黑洞向星团中心沉降，在这个区域，形成了一个完全由黑洞组成的核心。
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His colleague Stefan Gillessen said: “The galactic centre harbours the closest supermassive black hole known. Hence, it is the best place to study black holes in detail.”
Lurking at the centre of nearly every galaxy and gobbling up stars in their vicinity, supermassive black holes are a truly menacing feature of the universe.