Accretion Disk Assembly During Common Envelope Evolution: Implications for Feedback and LIGO Binary Black Hole Formation

Understand

During a common envelope episode in a binary system, the engulfed companion spirals to tighter orbital separations under the influence of drag from the surrounding envelope material.

• As this object sweeps through material with a steep radial gradient of density, net angular momentum is introduced into the flow, potentially leading to the formation of an accretion disk.
• The presence of a disk would have dramatic consequences for the outcome of the interaction because accretion might be accompanied by strong, polar outflows with enough energy to unbind the entire envelope.
• Without a detailed understanding of the necessary conditions for disk formation during common envelope, therefore, it is difficult to accurately predict the population of merging compact binaries.