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A new study has found that supermassive black holes are spinning faster than expected, which could change our understanding of their formation and evolution.
Scientists, using the method of "black hole archaeology", have investigated how the rotation of black holes is related to the accretion disk - the gas and dust surrounding these cosmic objects. The study, conducted as part of Sloan Digital Sky Survey (SDSS), found that black holes have accumulated material over 7 billion years of cosmic history not only through mergers but also by absorbing their surroundings. Logan Freese of the University of Connecticut notes:
Determining the rotation speed of black holes is a difficult task, as it is necessary to distinguish the black hole's own spin from the motion of its accretion disk. The researchers used a method reverberation mapping (SDSS Reverberation Mapping), which allowed us to observe radiation from the innermost regions of the accretion disk.
The results showed that black holes in more distant galaxies have even higher rotation speeds than those in closer ones, indicating a gradual build-up of angular momentum. This contradicts the traditional theory that rotation should be balanced by random mergers. As Fris explains, "When you look at the rotation of a black hole, you are essentially looking at its fossils.", that is, you study the history of its growth.
These discoveries can be verified using James Webb Space Telescope (JWST), which allows us to observe even earlier stages of the development of the Universe. Juna Kollmeier, director of SDSS-V, emphasizes the importance of such studies:
Thus, the results of this study may be the key to a deeper understanding of the evolution of supermassive black holes and the impact of their rotation on galaxy formation.
