English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

In a companion paper, we reported the self-consistent formation of quasaraccretion disks with inflow rates $\sim 10\,{\rm M_{\odot}\,yr^{-1}}$ down to<300 Schwarzschild radii from cosmologicalradiation-magneto-thermochemical-hydrodynamical galaxy and star formationsimulations. We see the formation of a well-defined, steady-state accretiondisk which is stable against star formation at sub-pc scales. The disks areoptically thick, with radiative cooling balancing accretion, but withproperties that are distinct from those assumed in most previous accretion diskmodels. The pressure is strongly dominated by (primarily toroidal) magneticfields, with a plasma $\beta \sim 10^{-4}$ even in the disk midplane. They arequalitatively distinct from magnetically elevated or arrested disks. The disksare strongly turbulent, with trans-Alfvenic and highly super-sonic turbulence,and balance this via a cooling time that is short compared to the diskdynamical time, and can sustain highly super-Eddington accretion rates. Theirsurface and 3D densities at $\sim 10^{3}-10^{5}$ gravitational radii are muchlower than in a Shakura-Sunyaev disk, with important implications for theirthermo-chemistry and stability. We show how the magnetic field strengths andgeometries arise from rapid advection of flux with the inflow from much weakergalaxy-scale fields in these 'flux-frozen' disks, and how this stabilizes thedisk and gives rise to efficient torques. Re-simulating without magnetic fieldsproduces catastrophic fragmentation with a vastly smaller, lower-$\dot{M}$Shakura-Sunyaev-like disk.

FORGE'd in FIRE II: The Formation of Magnetically-Dominated Quasar Accretion Disks from Cosmological Initial Conditions