Supersized Black Hole in an Unlikely Location
Astronomers have announced the discovery of a black hole that has “eaten” as much material as 17 billion Suns. A few such gargantuan black holes have been found elsewhere; what makes this one special is that it was found in a poor neighborhood, astronomically speaking.
Black holes are places where matter is so compressed, that nothing – not even light – can escape the grip of gravity. They frequently start life as the collapsed corpse of a massive star, but, under the right circumstances, they can really grow. If a black hole is frequently presented with “food” – matter it can swallow within its tight boundary – that boundary can grow. In a busy region, where lots of material is available, such as the crowded center of a big galaxy, black holes can grow until they contain millions of stars.
Many good-sized galaxies thus contain a “super-massive black hole” at their centers. Our Milky Way Galaxy has such a monster at its heart, which has swallowed enough matter to make 4 million Suns. But that’s still a long way from the super-sized black hole we just found.
Today we also know that galaxies like ours grow over time by swallowing smaller galaxy neighbors, in a process we call galactic cannibalism. If some parts of the victim galaxy are directed toward the giant black hole at the center of the cannibal, it can get swallowed by the giant black hole and help it to grow. (Some of us are reminded by this process of what’s been happening to banks in the U.S., where the largest banks and financial institutions have been swallowing smaller local banks whenever they can.)
At the centers of galaxies that live in a rich neighborhood – filled with other small galaxies they can be thinking about for lunch – giant black holes can grow to be “super-sized.” But in poor neighborhoods, there aren’t that many galaxies to munch on, and we thought black holes at the center of a galaxy would be limited in whether it could grow supersized.
The new discovery, made by a team headed by Berkeley professor Chung-Pei Ma, found the super-sized black hole in a galaxy known by its catalog number, NGC 1600. To our surprise, it resides in a poor neighborhood with only about 20 galaxies hanging out together. How it grew to be one of the largest black holes we know without many victim galaxies around it is still a mystery.
The monstrous black hole is located about 200 million light years from Earth, so that it poses no danger to our own neighborhood and will not interfere with continuing the presidential primaries or other local events. Understanding black holes and their role in the development of galaxies is high on the agenda of astronomers and in NGC 1600 they have a puzzling detail that doesn’t quite fit the standard story line.
For more on how astronomers discover such giant black holes, you can watch the non-technical lecture Chung-Pei Ma gave in the Silicon Valley Astronomy Lectures (that I have the pleasure of moderating) at:https://www.youtube.com/watch?v=LN9oYjNKBm8