NASA‘s James Webb Space Telescope (JWST) has examined a galaxy that formed just 430 million years after the big bang.
If scientists are correct, this galaxy is one of the very oldest in existence and could have been a nursery for ancient Population III stars – a holy grail of modern astronomy.
The galaxy, named GN-z11, has a supermassive black hole at its center that weighs the equivalent of 2 million suns.
Its exceptional brightness comes from all the hot, heavy materials that the black hole is sucking in.
This image is from the James Webb Space Telescope’s NIRCam (Near-Infrared Camera). It shows a portion of the GOODS-North field of galaxies. At the lower right, a pullout highlights the galaxy GN-z11, which is seen at a time just 430 million years after the Big Bang.
The JWST launched in 2021 to collect the faintest light from distant stars.
This gives us a glimpse back into the earliest days of our universe’s formation, around 13.8 billion years ago.
Its new discovery suggests that the space telescope is well equipped to deliver on its promises.
The galaxy was first spotted back in 2015 by the Hubble Space Telescope.
GN-z11 is brighter than the other stars and galaxies nearby.
At the time, scientists could tell that it was exceptional, but the Hubble Space Telescope wasn’t powerful enough to help them explain why.
Part of its brightness, astronomers have now claimed, is that the galaxy hosts a central, supermassive black hole that has two million times the mass of our sun.
It is rapidly accumulating matter, so the area around the black hole appears exceptionally bright.
GN-z11 is also the most far-away supermassive black hole ever described by astronomers.
Galaxy GN-z11, shown in the inset, as it was first spotted in 2015 by the Hubble Space Telescope
‘We found extremely dense gas that is common in the vicinity of supermassive black holes accreting gas,’ said lead scientist Roberto Maiolino, professor of experimental astrophysics at the University of Cambridge, in a statement.
‘These were the first clear signatures that GN-z11 is hosting a black hole that is gobbling matter,’ he said.
The JWST’s NIRCam (Near-Infrared Camera) located GN-z11 in the GOODS-North field of galaxies.
The new images from JWST may not appear to have the same level of detail as the 2015 Hubble image, but whereas the Hubble captured ultraviolet light, JWST was able to show infrared.
Infrared is a type light with a wavelength almost twice as long as ultraviolet. It matters in this case because there were some clues about GN-z11 that Hubble had missed because they could only bee seen in infrared.
The NIRCam revealed ionized chemical elements, which are often the signature of supermassive black holes that are accumulating material.
Along with this signature, the scientists also observed a strong ‘wind’ being blown by the galaxy at 800-1,000 kilometers per second (about 500 to 600 miles per second).
This, too, is a typical signature of a supermassive blackhole, said study co-author Hannah Übler.
‘Webb’s NIRCam (Near-Infrared Camera) has revealed an extended component, tracing the host galaxy, and a central, compact source whose colors are consistent with those of an accretion disk surrounding a black hole,’ she said.
Taken together, these factors explained the unusual brightness of GN-z11.
Maiolino, Übler, and their colleagues published their findings in the journal Nature.
Another team used the telescope’s NIRSpec (Near-Infrared Spectrograph) instrument to spot a clump of helium gas surrounding the galaxy.
‘The fact that we don’t see anything else beyond helium suggests that this clump must be fairly pristine,’ said Maiolino.
‘This is something that was expected by theory and simulations in the vicinity of particularly massive galaxies from these epochs – that there should be pockets of pristine gas surviving in the halo, and these may collapse and form Population III star clusters.’
Population III stars were some of the universe’s very first stars, made of helium and hydrogen.
Based on the fact that the scientists observed helium and nothing else, they think they have found one of these holy grails of astronomy.
A small box identifies GN-z11 in a field of galaxies (top right). In the middle, it can be seen zoomed in on. The far left box shows the helium gas halo around the galaxy, including a clump that can’t be seen in the infrared colors in the middle box. The graph at the bottom shows the distinct light signature of helium and no other element. Scientists concluded that this must mean the helium clump is a pristine remnant of the big bang
These Population III stars formed around the transition point in the early universe, when it was shifting from simplistic and disordered to complex and ordered.
Starting with its very first findings, astronomers have excitedly claimed that the JWST is revealing details about the early universe that overturn our understanding of astrophysics.
Not everyone agrees, however.
There may be simpler explanations than ‘everything we know is wrong,’ according to a recent study.
A team of researchers compared images taken by JWST to similar ones captured by the older Hubble Space Telescope, and they concluded that it’s not time to throw out the rules of astrophysics.
Instead, they suggest that the findings from both space telescopes are compatible, as long as scientists are willing to seek conventional explanations.
For instance, they suggest that perhaps some yet-to-be-understood conditions of the early universe made it possible for brighter stars to form.
