A bizarre supermassive black hole in an isolated part of the universe has forced scientists to rethink how rare these cosmic phenomena really are.
The newly discovered object, with a mass of 17 billion Suns, was detected by an international team of researchers. The object is located in NGC 1600, an elliptical galaxy 200 million light-years from Earth. NGC 1600 is found in a low-density environment with less than 100 companions in its vicinity. The discovery is described in a paper in the journal Nature.
The discovery is surprising because it was thought such large objects required galaxy collisions, or galactic cannibalism, from nearby companions to maintain their large appetites. “It’s a bit like finding a skyscraper in a Kansas wheat field, rather than in Manhattan,” said Professor Chung-Pei Ma, who led the international team of researchers, in a statement, adding that “to find one in relative isolation indicates that the black hole has long-ago tapped its sources of matter that allowed it to grow.”
So far the largest supermassive black holes (weighing more than 10 billion times the mass of the Sun) have been found in galaxies in the densest clusters. One of the largest supermassive black holes ever detected was observed in 2011 in NGC 4889, and is about 21 billion solar masses. NGC 4889 is one of the brightest galaxies in the Coma Cluster, one of the largest agglomeration of galaxies in the local universe with over 1,000 members. NGC 1600, by comparison, is a bit of an oddity.
The team believes NGC 1600 is a quasar remnant. A quasar is the most active phase of a supermassive black hole; as material falls into the black hole, it heats up and emits an incredible amount of light. NGC 1600 might have once shined brightly, but has since quietened down and it’s now asleep.
“The brightest quasars, probably hosting the most massive black holes, don’t necessarily have to live in the densest regions of the universe,” Ma added in a statement. “NGC 1600 is the first very massive black hole that lives outside a rich environment in the local universe, and could be the first example of a descendant of a very luminous quasar that also didn’t live in a privileged site.”
Interestingly, NGC 1600 may have once had more companions, but cannibalized them to achieve its size. “Within [its] group, NGC 1600 is by far the most brilliant member and outshines other members by at least three times, an indication that NGC 1600 may have cannibalized its former neighboring galaxies and their central black holes in its youth,” said lead author Jens Thomas.
This is the latest result from the MASSIVE Survey, which aims to study the properties of the 100 most massive elliptical galaxies within 300 million light-years of the Milky Way.