Why Magnetic Fields Make Black Holes Quiet ⚡ экспресс
Accretion disk models range from the standard thin disk dominated by thermal pressure to geometrically thick configurations supported by radiation or magnetic fields. In all cases, objects embedded in the disk (compact objects, stars, gas) undergo gravitational and hydrodynamic interactions leading to captures, mergers, and other processes. It is shown that the rates of such events, mediated by gravitational cross-sections, depend extremely strongly on the disk's relative thickness H/R — the dependence is inverse and scales as ~(H/R)⁻⁸. Meanwhile, in the outer regions of the disk, H/R can change by more than 1000 times depending on the dominant pressure support mechanism. Consequently, predictions of event frequencies can differ by tens of orders of magnitude: for example, accounting for magnetic pressure reduces capture rates by factors of 10¹⁰–10²⁰ compared to models that ignore magnetic fields. The results highlight the need for precise accounting of disk geometry and pressure sources when calculating observational signatures.
At the centers of many galaxies lurk supermassive black holes, surrounded by disks of gas, cosmic dust, and stars. Their collisions can spawn gravitational waves—ripples in spacetime. The old picture, developed by Rashid Sunyaev, portrayed this disk as thin and flat, like a packed dance floor: any movement causes a bump.
New research confirms: thickness rules the fate of collisions. Thin disk — cramped, thick disk — empty. Magnetic fields threading the disk can inflate it to enormous sizes, especially in the outer regions. Then, instead of a bustling cosmic mosh pit, near-absolute silence falls.
🎯 If the disk stayed flat like a packed dance floor, collisions would thunder nonstop. But magnetic fields transform it into an empty multi-story atrium, where encounters are almost impossible.