Cornell University astronomers have made an incredible discovery in the first image captured by NASA’s James Webb Space Telescope (JWST): a blob of light near the edge of SPT0418-47, one of the brightest star-forming galaxies from the early universe.
Gravitational lensing from a foreground galaxy had bent and magnified its ancient light into a distinctive circular shape known as an Einstein ring.
This potentially groundbreaking finding was published in The Astrophysical Journal Letters on February 17th, 2023, with IOP Publishing being responsible for its distribution.
Findings based on the research
The astronomers found a companion galaxy previously unnoticed behind the light of another foreground galaxy.
What makes this discovery even more amazing is that despite its young age – estimated at only 1.4 billion years old – this companion galaxy appears to have already experienced multiple generations of star formation.
Bo Peng, a doctoral student in astronomy and leader of the data analysis team, said, “We found this galaxy to be super-chemically abundant, something none of us expected. The James Webb Space Telescope changes the way we view this system and opens up new venues to study how stars and galaxies formed in the early universe.”
Six galaxies have been discovered in the early universe, upending what scientists previously understood about the origins of the galaxies in the universe.
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Earlier images taken by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile also hinted at the presence of an object in the Einstein ring.
However, it was only through the superior infrared vision of JWST that astronomers were able to clearly resolve the object. The new galaxy is estimated to be roughly 10% of the age of the universe and is located close to its foreground partner.
Confirming the discovery
The team investigated the spectral data embedded in pixels from JWST’s NIRSpec instrument and found a second light source inside the ring.
Further analysis of the light’s chemical composition confirmed that both galaxies had similar redshifts, indicating that they were roughly the same distance from Earth.
To verify their discovery, astronomers returned to earlier ALMA observations and found an emission line of ionized carbon that closely matched what JWST had observed, confirming the presence of the new galaxy.
Merging between galaxies
The team estimated that the companion galaxy was within 5 kiloparsecs of its partner, which is much closer than other satellites like the Magellanic Clouds, which are around 50 kiloparsecs away from Earth.
Astronomers propose that the proximity of the two galaxies suggests that they are likely to interact and potentially merge, offering valuable insights into the development of early galaxies into larger ones.
Discovery of the same metals as our sun
Astronomers were surprised to find that despite the galaxies being younger and less massive than our sun, their mature metallicity was similar.
It means they had built up quantities of heavier elements such as carbon, oxygen, and nitrogen, which are typically inherited over billions of years.
According to the astronomers, the galaxies they are observing are from a time when the universe was less than 1.5 billion years old, therefore much earlier than the 4 billion year age of our sun and its 8 billion years of metal-building.