Detailed stellar-evolution modeling of the formation channel

Investigate the formation of GW190814-like binary black hole systems using detailed stellar evolution calculations during Roche-lobe overflow to assess whether a fully stable, strongly non-conservative first mass-transfer episode can produce such systems without invoking a common-envelope phase.

Background

The preferred channel in this work involves a first Roche-lobe overflow transitioning into a common-envelope phase, followed by a stable second mass-transfer episode. However, the authors highlight uncertainties because COSMIC does not model the donor’s response during stable mass transfer and notes that some binding energy parameter assumptions may be too large, potentially favoring mergers during the first common envelope.

They outline an alternative scenario in which the first mass transfer remains stable and strongly non-conservative from a smaller zero-age main sequence semimajor axis, but defer a rigorous assessment because detailed stellar evolution during RLOF is not included in COSMIC.