The Stellar Winds Atlas II: Black Hole Formation at Solar Metallicity

Abstract

Stellar winds are a primary source of uncertainty in predicting the masses of black holes (BHs) from massive stars. At solar metallicity, theoretical models lead to widely divergent results due to differing wind prescriptions. A key obstacle remains the lack of systematic investigations across a common parameter space. To address this, we construct a ``Wind Atlas'' using detailed 1D MESA stellar evolution models and population synthesis techniques to estimate the Galactic population of solar metallicity BH progenitors. We systematically investigate 14 distinct wind models, ranging from the most traditional and widespread prescriptions to the most recent. By evaluating stellar evolution across this extensive grid, we show that the final BH mass is dictated by a fundamental bifurcation: whether a star collapses as a cool supergiant or is first stripped of its envelope to become a Wolf-Rayet (WR) star. If a star enters the WR stage, its strong thick winds dominate, making the final mass sensitive to the WR wind prescription while largely erasing the memory of its prior mass-loss history. Conversely, stars that face core collapse as supergiants form significantly more massive BHs, producing a mass peak around an initial mass of 40 $M_\odot$. Rather than simply reproducing these divergent outcomes, our comprehensive evaluation demonstrates that this bifurcation is universally controlled by the highly uncertain mass loss during the cool supergiant phase. This framework strongly constrains the problem of BH mass prediction by identifying two key bottlenecks for future studies: envelope stripping efficiency and WR mass-loss rates. Our atlas provides a clear baseline for interpreting current theoretical discrepancies and testing wind models against observational constraints, such as the Galactic WR/OB population ratio.