Constraining ultralight dark matter models from observed black hole distributions

We consider the quantum mechanical collapse of a ball of dust in the context of ultra-light dark matter. In the classical Oppenheimer-Snyder collapse of a ball of dust to a black hole each dust particle is assumed to be infinitely small, infinitely light and to interact only gravitationally with other matter. This approximation is not perfect as infinitely light particles are infinitely large in size and would never be localized within the dust ball or horizon. Ultra-light dark matter particles ($m \sim 10^{-23}$ eV) come close to the attributes classical dust, except that they are so small that quantum effects play an important role. In this talk we reconsider the Oppenheimer-Schneider model without neglecting quantum effects, and explore interesting facts about the Universe. I plan to discuss the smallest black hole that can be formed from these ultralight particles. Once black holes reach this mass they could feed on dark matter and increase in size. This could affect the black hole distribution in that black holes of a certain mass range would be difficult to find.