Surprise! The Universe has a third way to form black holes
It isn’t just supernovae or merging neutron stars. In fact, it’s the quietest way of all!
“N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey. During this period, six normal supernovae have occurred within the galaxies we’ve been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae.” -Scott Adams
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.
If direct collapse is possible, we should see some massive stars with just the right properties disappearing with no explosion.
For the first time, astronomers observed a 25 solar mass star just disappear.
Direct collapse is the only explanation possible.
As many as 30% of massive stars should become black holes in this way, which is now verified for the first time.
Mostly Mute Monday tells the astronomical story of an object, process or phenomenon in images, visuals and no more than 200 words.
Starts With A Bang is now on Forbes, and republished on Medium thanks to our Patreon supporters. Ethan has authored two books, Beyond The Galaxy, and Treknology: The Science of Star Trek from Tricorders to Warp Drive!