"In two seminal papers from the 1970s that described the accretion disks fueling supermassive black holes, scientists assumed that thermal pressure—the change in pressure caused by the changing temperature of the gas in the disks—played the dominant role in preventing such disks from collapsing under the tremendous gravity they experience close to the black hole. They acknowledged that magnetic fields might play a minor role in helping to shore up the disks. In contrast, the new simulation found that the pressure from the magnetic fields of such disks was actually 10,000 times greater than the pressure from the heat of the gas."
Here's a long-form presentation from study lead Phil Hopkins at
https://www.youtube.com/watch?v=JAiFCbRD0oI
Paper, including discussion of code
https://arxiv.org/abs/2309.13115v2