Astronomers have discovered surprising details about a very distant galaxy, GN-z11, which existed just 420 million years after the Big Bang. This makes GN-z11 one of the earliest and most distant galaxies ever observed.
Located in the constellation Ursa Major, GN-z11 is a young but already massive galaxy, forming stars at a rate 20 times faster than our Milky Way. Despite being 25 times smaller and containing only 1% of the Milky Way's mass, GN-z11 harbours a supermassive black hole at its centre, rapidly gobbling up matter.
This discovery, made using the James Webb Space Telescope, challenges our current understanding of how galaxies form so quickly in the early universe and how supermassive black holes can grow so large so early on.
"We found extremely dense gas that is common in the vicinity of supermassive black holes accreting gas," explained principal investigator Roberto Maiolino of the Cavendish Laboratory and the Kavli Institute of Cosmology at the University of Cambridge in the United Kingdom. "These were the first clear signatures that GN-z11 is hosting a black hole that is gobbling matter."
Using Webb, the team also found indications of ionised chemical elements typically observed near accreting supermassive black holes. Additionally, they discovered a very powerful wind being expelled by the galaxy. Such high-velocity winds are typically driven by processes associated with vigorously accreting supermassive black holes.
"Webb's NIRCam (Near-Infrared Camera) has revealed an extended component, tracing the host galaxy, and a central, compact source whose colours are consistent with those of an accretion disc surrounding a black hole," said investigator Hannah Ãœbler, also of the Cavendish Laboratory and the Kavli Institute.
Together, this evidence shows that GN-z11 hosts a 2-million-solar-mass, supermassive black hole in a very active phase of consuming matter, which is why it's so luminous.
