Which came first? Black-hole Spin or Supernova Kick

While the origins of black hole spins remain a mystery, it's commonly assumed that if black holes come from isolated massive star binaries, their spins should align with orbital angular momentum. However, this notion is often in conflict with observations. We will question this long-held viewpoint and explore various mechanisms that can spin up BHs before or during supernovae. In addition to natal spins, we will discuss methods that can spin BHs isotropically, parallel to supernova kicks, and perpendicular to supernova kicks. These different mechanisms leave behind distinct imprints in the observable distributions of spin magnitudes, spin-orbit misalignments and the effective inspiral spin of merging binaries. In particular, these mechanisms allow even the binaries originating in the field to exhibit precession and retrograde spin. This broadens the parameter space allowed for isolated binary evolution, which was previously thought to be exclusive to dynamically assembled binaries.