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Possible missing link in galactic evolution discovered

7 October 2024

Caption provided by NASA: The galaxy GS-NDG-9422 may easily have gone unnoticed. However, what appears as a faint blur in this James Webb Space Telescope NIRCam (Near-Infrared Camera) image may actually be a groundbreaking discovery that points astronomers on a new path of understanding galaxy evolution in the early universe. Detailed information on the galaxy’s chemical makeup, captured by Webb’s NIRSpec (Near-Infrared Spectrograph) instrument, indicates that the light we see in this image is coming from the galaxy’s hot gas, rather than its stars. That is the best explanation astronomers have discovered so far to explain the unexpected features in the light spectrum. They think that the galaxy’s stars are so extremely hot (more than 140,000 degrees Fahrenheit, or 80,000 degrees Celsius) that they are heating up the nebular gas, allowing it to shine even brighter than the stars themselves. The authors of a new study on Webb’s observations of the galaxy think GS-NDG-9422 may represent a never-before-seen phase of galaxy evolution in the early universe, within the first billion years after the big bang. Their task now is to see if they can find more galaxies displaying the same features.
a photo showing outer space, including a box showing a zoomed-in view of galaxy GS-NDG-9422

Using the James Webb Space Telescope, a team of researchers has spotted an unusual early galaxy with gas clouds that outshine its stars, providing a glimpse into a possible ‘missing link’ phase of galactic evolution. The research was published in a paper in Monthly Notices of the Royal Astronomical Society, with St Peter’s Research Associate Dr Aayush Saxena as one of the team of authors. Dr Saxena is part of the James Webb Space Telescope instrument team and works alongside the paper’s lead author and fellow observational astrophysicist Dr Alex Cameron at Oxford’s Department of Physics (sub-department of Astrophysics).

Dr Saxena said,

‘Discoveries like this galaxy are exactly why the Webb Telescope was built and launched, and we are routinely discovering these fun surprises in pretty much every new dataset that we collect. The prospects for transforming our understanding of how galaxies like our Milky Way formed and evolved are incredibly exciting in the coming years.’

You can learn more about the team’s research and its potential impact in this NASA article (written for a non-specialist audience). To access their research paper, click here.

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