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31 May 2024
NIRSpec instrument shows record-breaking red-shift of starlight, corresponding to 290 million years after the Big Bang.
Astronomers analyzing imagery from the James Webb Space Telescope (JWST) to study the so-called “Cosmic Dawn” now believe they have located the most distant galaxy ever recorded.
Based on data from JWST’s near-infrared spectrograph (NIRSpec) instrument, the international team collected a spectrum from a galaxy with a record-breaking red-shift corresponding to light emitted just 290 million years after the Big Bang.
Oldest galaxy
The work remains subject to publication and peer review, but in a NASA blog post team members Stefano Carniani from Scuola Normale Superiore in Pisa and Kevin Hainline from the University of Arizona explained the observations made so far.
While conducting the JWST Advanced Deep Extragalactic Survey (JADES) in early 2023, the astronomers identified hundreds of possible galaxies dating to first 650 million years of the universe.
One of those galaxies (now known as “JADES-GS-z14-0”) appeared surprisingly bright for its age, and follow-up work using Webb’s near-infrared camera (NIRCam) instrument also indicated a particularly high red-shift.
In January this year, the team was able to collect a spectrum of the galaxy over ten hours, confirming a record-breaking red-shift of 14.32. That compared with the previous record of 13.2, meaning that by some distance it became the earliest galaxy yet to be observed.
“From the images, the source is found to be over 1600 light years across, proving that the light we see is coming mostly from young stars and not from emission near a growing supermassive black hole,” wrote Carniani and Hainline in the NASA blog, adding that this raised a big question: how can such a bright and large galaxy appear within 300 million years of the Big Bang?
MIRI shows oxygen
Additional observation data from JWST’s mid-infrared instrument (MIRI) also showed bright emission lines corresponding to hydrogen and oxygen - another surprise, as it suggests that multiple generations of very massive stars had already lived their lives by the time the galaxy was observed.
“All of these observations, together, tell us that JADES-GS-z14-0 is not like the types of galaxies that have been predicted by theoretical models and computer simulations to exist in the very early universe,” conclude Carniani and Hainline.
“Given the observed brightness of the source, we can forecast how it might grow over cosmic time, and so far we have not found any suitable analogs from the hundreds of other galaxies we’ve observed at high redshift in our survey.”
They suggest that the discovery, assuming corroboration through peer review, will have profound implications for the predicted number of bright galaxies seen in the early universe - with astronomers likely to find many similar objects, perhaps at even earlier dates.
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