Astronomers have discovered that an enormous black hole occupies the center of our own galaxy, and the centers of many other galaxies too, extending all the way back to the first 1 billion years of the universe’s history. In the latest discovery reported in Nature magazine, such an object was found when the universe was only 690 million years old.
These “supermassive” black holes act like the central fire in a winter home, eagerly growing by accreting any and all material that falls within its notoriously unforgiving boundries, even growing into a bonfire if the occupants would allow it.
Similarly to fires, black holes also can “bulk up” to significant sizes if fed not by firewood but rather by entire stars, with the “bonfire” equivalent called a supermassive black hole. The puzzle in this field is not so much how to build a supermassive black hole, but rather where the black hole “seeds” come from in the first place.
This is because the only way we know to make a black hole is by the destruction of a massive star (or of a massive star in a binary system). Imagine that we successfully
blow up a ten solar mass star, and then let us place that new ten solar mass black hole into a “tasty” environment. Now then, how long do we have to keep “feeding” stars to it before it reaches a mass 780 million solar masses such as the one just found at that tender age of 690 million years?
This exercise has been carried out in computer simulations for many years now, with the answer being that it would take too long to grow a black hole in this manner explain the recent findings.
We can only reasonably explain the presence of supermassive black holes so early on in the universe’s history if the “seed” started out not as a ten solar mass black hole, but instead as a 1000-10,000 solar mass black hole.
There is nothing to prevent such intermediate mass objects from forming in the early universe and if so, then there may be large numbers of them just waiting to be discovered by amateur and professional astronomers alike. Happy hunting!