by There is evidence that the first generation of stars in the universe has come to light, thanks to observations made by the James Webb Space Telescope (JWST). The proof lies in one of the most distant known galaxies.
The galaxy, named GN-z11he found out at the Hubble Space Telescope in 2015 and, before the launch of the James Webb Space Telescope, it was considered the most distant galaxy. With a redshift of 10.6, it makes more sense to talk about how long ago it was there, rather than how far away it is. That’s because we see GN-z11 as it was exactly 430 million years after the Big bang because of the time it took for its light to travel to our corner of the cosmos. For comparison, the globe is today 13.8 billion years old.
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Therefore, GN-z11 was a prime target for JWST to study. Now, two new papers describe profound discoveries about GN-z11 that reveal crucial details about how galaxies in the early universe were able to grow.
GN-z11 is the most luminous galaxy known at this particular redshift, and indeed this is a common theme for high redshift galaxies now found almost regularly in the early universe by the JWST. Many of them appear much brighter than our models of galaxy formation predict they should be. These predictions are based on the standard model of cosmology.
Now, new observations from the JWST seem to have shed some light on what’s going on.
An astronomy team, led by Roberto Maiolino from the University of Cambridge, has explored GN-z11 with JWST’s two near-infrared instruments, the Near-Infrared Camera (NIRCam) and the Near-Infrared Spectrometer (NIRSpec). The researchers found evidence for the first generation of stars, known as Population III stars, as well as for a supermassive black hole reduce a huge amount of material and grow at a very accelerated rate.
Scientists can calculate a star’s age based on its abundance of heavy elements, which would have been created by previous generations of stars that lived and died, spewing those heavy elements into space where they are eventually recycled in star-forming regions to form new ones. stellar bodies. Population I stars are the youngest stars formed in the last five to six billion years, and have the highest abundance of heavy elements. Our sun is a Population I star. Older stars have fewer heavy elements because there have been fewer previous generations of stars. These are called Population II stars, and they live in our oldest regions The Milky Way Galaxy.
Population III stars, however, were only hypothetical until now.
These were the first stars to form, and because no other stars came before them, they would contain no heavy elements and would only be made of hydrogen and helium as forged during the Big Bang. It is also thought that these first stars were extremely luminous, with masses equal to at least a few hundred suns.
Although astronomers have yet to see Population III stars directly, Maiolino’s team found indirect evidence for them in GN-z11. NIRSpec saw droplets of ionized helium near the edge of GN-z11.
“The fact that we see nothing else beyond the helium suggests that this lump must be relatively pristine,” Maiolino said in a. statement. “This is what was expected by theory and simulations in the vicinity of massive galaxies from these periods – that there should be pockets of stagnant gas living in the halo, and these could collapse and become Population III stars formation.”
This helium gas is being ionized by an object that produces massive amounts of ultraviolet light, and that object is known as the Population III stars. The helium seen in its material may be left over from the formation of that star. The amount of ultraviolet light needed to ionize all that gas requires a total of about 600,000 solar masses of stars, shining simultaneously 20 trillion times brighter than our sun. These figures suggest that distant galaxies such as GN-z11 would be more capable of forming massive stars than galaxies in the modern universe.
Meanwhile, according to the second set of results, Maiolino’s team also found evidence for a two-million-solar black hole at the core of GN-z11.
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“We found very dense gas that is common in the vicinity of supermassive black holes that accumulate gas,” Maiolino said in the same statement. “These were the first clear signatures that GN-z11 is hosting a black hole gobbling matter.”
The team also detected a powerful plume of radiation emanating from the accretion disk of matter swirling around the black hole as well as ionized chemical elements typically found near accreting black holes. This is the most distant supermassive black hole discovered so far, the team says, and its gluttonous appetite causes its accretion disk to become dense and hot, and shine brightly. This, along with Population III stars, is what makes GN-z11 shine so brightly, according to the researchers, without breaking standard cosmology as some have is required in advance.
The study of the ionized helium cluster and Population III stars has been accepted for publication in the journal Astronomy & Astrophysics, and a preprint is available. to be found here. Meanwhile, the study of NIRCam observations of the black hole was published on January 17 in the journal nature.
