Supermassive black holes are often portrayed as gigantic and ravenous beasts, ready to destroy anything that gets too close. And while that it is certainly true, they can also help create new stars. New evidence suggests that this ability might extend much further than previously thought.
As reported in Astronomy & Astrophysics, researchers have observed the emission of a jet of high-energy particles from an active supermassive black hole 9 billion light-years away. The jet produced by the black hole, which sits at the core of a massive galaxy, produced an enormous bubble of hot gas. At the edge of this bubble, researchers have found six galaxies, and four of them are forming a lot more stars than they should.
These galaxies are forming stars at up to 60 times the current rate of the Milky Way. This is between two and five times higher than the average galaxy with the same mass and the same distance from Earth. Stars form when dense clouds of gas and dust collapse under their own gravity. The team suspects that the hot bubble of gas is compressing the cold gas present in those galaxies, and it is this that is inducing the star formation.
“This is the first time we've seen a single black hole boost star birth in more than one galaxy at a time,” lead author Roberto Gilli of the National Institute of Astrophysics (INAF) in Bologna, said in a statement. “It's amazing to think one galaxy's black hole can have a say in what happens in other galaxies millions of trillions of miles away.”
More observations will be necessary to absolutely link the black hole to the formation of the new stars, but the team is excited by what they have witnessed so far. More often than not, the jets from supermassive black holes create a “negative feedback” by thinning and heating the gas clouds where stars form.
Positive feedback has only been witnessed on much smaller scales. Either a more modest star-formation enhancement or only very close galaxies (less than 50,000 light-years) were affected. The scale of this apparent event is beyond anything witnessed before.
"It's only because of this very deep observation that we saw the hot gas bubble produced by the black hole," said co-author Colin Norman of Johns Hopkins University. "By targeting objects similar to this one, we may discover that positive feedback is very common in the formation of groups and clusters of galaxies."
The research was based on observation conducted by NASA’s Chandra X-ray Observatory and follow-up observation by the European Southern Observatory's Very Large Telescope (VLT) and the Large Binocular Telescope (LBT).