Understand
Circumbinary accretion occurs throughout the universe, from the formation of stars and planets to the aftermath of major galactic mergers.
- We present an extensive investigation of circumbinary accretion disks, studying circular binaries with mass ratios ($q\equiv M_2/M_1$) from 0.01 to 1 and at each mass ratio probing the effects of disk thickness and viscosity.
- We study disks with aspect ratios $H/r\in\{0.1, 0.05, 0.033\}$, and vary both the magnitude and spatial dependance of viscosity.
- Although thin accretion disks have previously been found to promote rapid inspirals of equal-mass binaries, we find that gravitational torques become weaker at lower mass ratios and most binaries with $0.01\leq q\leq0.04$ outspiral, which may delay the coalescence of black hole binaries formed from minor mergers and cause high-mass exoplanets to migrate outwards.