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Most-detailed-ever simulations of black hole solve longstanding mystery

An international team of researchers has constructed the most-detailed, highest-resolution simulation of a black hole to date. The simulation proves theoretical predictions about the nature of accretion disks -- the matter that orbits and eventually falls into a black hole -- that have never before been seen. Among the findings, the team of computational astrophysicists found that the inner-most region of an accretion disk aligns with its black hole's equator. This discovery solves a longstanding mystery, originally presented by Nobel Prize-winning physicist Jim Bardeen and astrophysicist Jacobus Petterson in 1975. At the time, Bardeen and Petterson argued that a spinning black hole would cause the inner region of a tilted accretion disk to align with its black hole's equatorial plane. After a decades-long, global race to find the so-called Bardeen-Petterson effect, the present team's simulation found that, whereas the outer region of an accretion disk remains tilted, the disk's inner region aligns with the black hole. A smooth warp connects the inner and outer regions. The team solved the mystery by thinning the accretion disk to an unprecedented degree and including the magnetized turbulence that causes the disk to accrete.

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