It is widely accepted that every massive galaxy hosts a super-massive black hole. However, the origin of these massive black holes are yet to be revealed. Professor Woo’s group reports new results on the population of active black hoes in the present-day universe. Based on a large optical spectroscopic survey data and careful corrections for the sample selection bias, they were able to constrain the number density of black holes down to the intermediate-mass regime (~10,000 solar mass), providing an important constraint for the origin of black holes as the currently available various black hole seed scenarios predict different black hole number density and occupation fraction. These results are crucial for searching for intermediate-mass black holes with future large surveys such as NASA’s SPHEREx mission.

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