Formation of discs around super-massive black hole binaries

TL;DR

This study uses numerical simulations to explore how turbulent molecular clouds evolve into different gas structures around supermassive black hole binaries depending on their orbital inclination.

Contribution

It introduces a modified SPH simulation approach to analyze the formation of mini-discs and circumbinary rings based on orbital inclination.

Findings

Aligned orbits produce mini-discs aligned with the binary.

Perpendicular orbits lead to misaligned mini-discs.

Counter-aligned orbits form a counter-rotating circumbinary ring.

Abstract

We model numerically the evolution of $10^4M_\odot$ turbulent molecular clouds in near-radial infall onto $10^6M_\odot$, equal-mass super-massive black hole binaries, using a modified version of the SPH code GADGET-3. We investigate the different gas structures formed depending on the relative inclination between the binary and the cloud orbits. Our first results indicate that an aligned orbit produces mini-discs around each black hole, almost aligned with the binary; a perpendicular orbit produces misaligned mini-discs; and a counter-aligned orbit produces a circumbinary, counter-rotating ring.