Stellar-Mass Binary Black Holes formed through Chemically Homogeneous Evolution

The subject of this research is a recently proposed channel of binary black hole evolution: chemically homogeneous evolution. This theory has the potential to explain how binary black holes could possibly merge within the age of the universe and emit detectable gravitational waves. A sufficient amount of rotation achieved through tidal forces can cause internal mixing within each star in a binary system. This mixing keeps the stars from expanding past their Roche Lobes and eventually converts most of the hydrogen in the star to helium, creating a pair of Wolf Rayet stars and eventually a black hole binary. This research adds the channel of chemically homogeneous evolution into population synthesis code COMPAS, creating a single environment for self-consistently testing multiple channels of binary evolution, including isolated evolution via mass transfer and common envelope phases. Furthermore, the merger rate for chemically homogeneously evolving binaries is calculated as a function of redshift, and the results are shown for runs at two different metallicities.