Data from the James Webb Space Telescope (JWST) has confirmed four galaxies dating to when the universe was around 300–500 million years old.
The telescope was designed to probe the early universe and initial surveys have identified many possible candidate galaxies of extremely high redshift – a measure of the speed that helps gauge distance.
Due to the expansion of the universe, light from distant objects shifts to wavelengths towards the red end of the spectrum — the redder the image, the more distant the object.
Currently, the only way to know that galaxies are at those redshifts is to confirm them with the help of a spectroscope – a tool astronomers use to better understand the physics of objects in space.
The galaxies described in two new papers published in Nature Astronomy have distinctive spectra (range of colours) in ultraviolet light wavelengths.
This differentiates them from other galaxies that have similar properties, the researchers say.
Brant Robertson, from the University of California Santa Cruz, Sandro Tacchella, from the University of Cambridge, and colleagues analysed images from JWST’s near-infrared camera.
They identified four galaxies: JADES-GS-z10-0, JADES-GS-z11-0, JADES-GS-z12-0, JADES-GS-z13-0.
While JADES-GS-z10-0 and JADES-GS-z11-0 were known previously from Hubble imaging, JADES-GS-z12-0 and JADES-GS-z13-0 were newly discovered.
The study determined the galaxies’ star-formation rates, sizes and other properties, indicating that each galaxy could contain 100 million solar masses (one solar mass is equal to about 333,000 times the mass of the Earth) in stars, in stellar populations that are less than one hundred million years old.
The authors suggest the observations indicate that the galaxies formed rapidly with intense internal radiation fields.
The study authors write: “We conclude by emphasising that the results reported here represent a milestone for the JWST mission, pushing the spectroscopic frontier to a markedly earlier epoch of galaxy formation.”
They add: “This is just a starting point for the mission.”
In the companion paper, Emma Curtis-Lake, from the University of Hertfordshire, and colleagues used JWST’s near-infrared spectrometry instrument to confirm galaxies (JADES-GS-z12-0 and JADES-GS-z13-0) further away than those identified by the Hubble space telescope.
It also confirmed the two objects originally detected with Hubble (JADES-GS-z10-0 and JADES-GS-z11-0) to be inhabiting the universe when it was less than 350 million years old.
The data does not show fingerprints of complex elements such as carbon, oxygen and nitrogen, indicating that the stars have not yet processed the pristine hydrogen and helium left over from the Big Bang to produce large stores of these heavier elements in the galaxies.
The authors suggest their findings demonstrate the rapid emergence of the first generations of galaxies.
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