thousand_cube

Circumbinary disk could maintain efficient accretion through fast radial gas streams.

Recently, we run 3d MHD simulations for disk around single mass object and disks around binary objects to measure to what extent the accretion rates are affected by the binary torque with respect to single mass case. We find the circumbinary disks have comparable rate of accretion than normal single mass disks. Our simulations demonstrate that for binaries with mass ratios of 1 and 0.1, there is essentially no difference between the accretion rate at large radius in the disk and the accretion rate onto the binary. We find the accretion is maintained via narrow gas stream with fast inflow speed which is well explained by the small subset of gas trajectories traveling from the inner edge of the disk to the binary. As illustrated on the top parallel coordinates plot, the fluid elements, treated as particles, within a ring at the gap edge of the circumbinary disk are represented with orange color lines threading their instantaneous location in position-velocity phase space. Only a tiny fraction of the total, which are colored in blue/green, falls onto the binary, where green highlighted fluid particles at the gap edge (r=2) (paper link at ADS & astro-ph). (ADS astro-ph).