Surprise! The Universe Has A Third Way To Form Black Holes

By Ethan Siegel

In addition to formation by supernovae and neutron star mergers, it should be possible for black holes to form via direct collapse. For the first time, we caught one red-handed, not just in simulations as shown here.
Aaron Smith/TACC/UT-Austin

 When a massive enough star runs out of fuel in its core and collapses, the resulting Type II supernova will produce a black hole.

Supernovae that aren't quite massive enough will produce neutron stars instead, which themselves will make black holes if they either accrete more matter or collide with another neutron star.

These two processes both enrich the Universe with heavy elements: supernovae with elements like iron, silicon, sulphur and phosphorous, while neutron star collisions create gold, mercury, lead and uranium.

But in theory, there should be a third way: through direct collapse.

If a massive enough gas cloud collapses under its own gravity, it should form a black hole directly, without any intervening star.

This is one of the leading theories for how supermassive black holes begin, including at such early times in the ultra-distant Universe.

Read more on Forbes.