Question: how are black holes created.

David Sobral answered on 10 Mar 2020:

The most common way is for the core of really massive stars (many times more massive than our Sun) to collapse at the end of the star’s life and become a black hole. This happens when the core, typically fully made of “Iron” and containing the mass of a few Suns starts to collapse on itself and nothing can stop that creating a black hole.

In the early Universe, it has been theorised that some black holes might have been made (huge ones of almost 1 million solar masses!) directly from gas clouds without ever passing through a star phase! These are called direct collapse black holes, and one of the galaxies I discovered is currently a really good candidate for hosting a black hole formed by this mechanism! Hopefully with new observations of the distant Universe we will be able to know if this really happens and how important this formation mechanism is to form the super massive black holes that nowadays we find in the centres of pretty much every galaxy.