MASSIVE BLACK HOLE FORMATION. “The Renaissance simulations show that the target haloes remain metal-free and are not exposed to any ionizing radiation. Their thermodynamic evolution and collapse are therefore primarily controlled by the growth history of the halo and the impinging LW flux. With these priors, we can safely neglect star formation and feedback, focusing on the dynamics of collapse.” (LH = Lyman–Werner).
https://www.nature.com/articles/s41586-019-0873-4