The black hole spin in coalescing binary black holes and high-mass X-ray binaries

During my PhD study, I was working on two types of Black Hole (BH) binaries, i.e. coalescing binary BHs and BH High-mass X-ray binaries (HMXBs). Most of the measured spin chi_eff are quite low, while three BH spin measurements in HMXBs show only values near the maximum. My study is focused mainly on the detailed stellar and binary evolution by tracking the evolution of angular momentum of the BH progenitor star in BH binaries. More specifically, we systematically studied the origin of the BH spin in these two different BH binaries systems. Furthermore, I have been working on a project that is related to a detailed comparison of the implementation for chemical mixing and angular momentum transport between two stellar evolution codes, namely, MESA and GENEVA codes. More specifically, we want to understand the minimum rotation that is required for chemically homogeneous evolution to occur.