As soon as it got to work, the James Webb Space Telescope (JWST) may have already seen the most distant galaxy known. Cataloged as GLASS-z13, it represents the state of the cosmos some 300 million years after the Big Bang.
The result is still preliminary – in more ways than one. For starters, the study, led by Rohan Naidu of the Harvard & Smithsonian Center for Astrophysics (USA), has been submitted to the Astrophysical Journal Letters, but is still awaiting review and acceptance. In addition, it builds on observations from the Webb starter package, where uncertainties about accuracy can still be significant. But the researchers made sure that such doubt should not hover above a variation of 10%, which already puts the finding in a very relevant position. Even because, in addition to the potentially record-breaking galaxy, they found one more, almost as distant (and old) as.
To estimate how deep they are seeing, astronomers look at the “redshift” of light, represented by the letter z. It indicates how much the wavelength of light has been “stretched” along its journey through space that is itself expanding. The further the light travels, the more it stretches. The most distant confirmed galaxy seen by Hubble (GN-z11) is z 11 and represents an epoch about 400 million years after the Big Bang. GLASS-z11, one of the new discoveries, potentially ties with it. And GLASS-z13, as the name suggests, appears to be z 13, plunging another 100 million years into the past.
With that, it also kind of ties with a candidate for the most distant galaxy ever seen, HD1, a discovery presented last April. But more important than potential records is the significance of the new findings – they are revealing that the Universe evolved faster than previously thought.
The most accepted models suggest that galaxies like these, old, large and bright enough to be seen (the authors estimate that GLASS-z13 already appears to have a mass of 1 billion suns), should be rarer. When the GN-z11 was discovered in 2015, it could have been a stroke of luck. Then came HD1, with uncertain confirmation. And now it was only Webb looking deeper for the first time with his infrared gaze that he had already found two other potential representatives of this era. According to Naidu and his colleagues, it was expected that one would need to look at an area of the sky ten times larger to find this frequency of finds.
This implies that relatively chunky galaxies were probably already easy figures 300 million years after the beginning of the Universe – something unexpected, which in turn indicates that Webb, looking even deeper, should quietly break current records. “If these candidates are confirmed, it is clear that the JWST will be very successful in pushing the cosmic frontier all the way to the edge of the Big Bang,” the researchers write.
This column is published on Mondays, in Folha Corrida.
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