Thanks to observations made by James Webb , scientists discover up to 87 possible candidates for the oldest galaxy ever discovered to date.
Early release observations from the James Webb Space Telescope have revealed 87 galaxies that could be the first known in the universe.
The finding, by a team of astronomers led by Haojing Yan at the University of Missouri, takes one step closer to finding out when galaxies first appeared in the universe, between 200 and 400 million years after the Big Bang, Yan said. , associate professor of physics and astronomy and lead author of the study.
“Finding such a large number of galaxies in the early parts of the universe suggests that we might need to revise our previous understanding of galaxy formation ,” Yan said in a statement. “Our finding gives us the first indication that many galaxies could have formed in the universe much earlier than previously thought.”
In search of the oldest
In the study, the astronomers searched for potential galaxies at “very high redshifts.” Yan said the concept of redshift in astronomy allows astronomers to measure how far away distant objects are in the universe, such as galaxies, by looking at how colors change in the light waves they emit.
“If a light-emitting source is moving toward us, the light is being ‘squeezed,’ and that shorter wavelength is represented by blue light, or blueshift,” Yan said. “But if that [light] source is moving away from us, the light it produces is ‘stretched’ and shifts to a longer wavelength that is represented by red light, or redshift.”
Yan said Edwin Hubble’s discovery in the late 1920s that our universe is constantly expanding is key to understanding how redshifts are used in astronomy.
“Hubble confirmed that galaxies outside our Milky Way are receding from us, and the more distant they are, the faster they are receding,” Yan said. “This relates to redshifts through the notion of distances: the greater the redshift of an object, such as a galaxy , the further it is from us.”
James Webb helping science
The James Webb was instrumental in this discovery because objects in space such as galaxies that are at high redshifts (11 and above) can only be detected using infrared light, according to Yan. This is beyond what NASA’s Hubble Space Telescope can detect because the Hubble telescope only sees from ultraviolet to near-infrared light.
“The most powerful infrared telescope, the James Webb has the sensitivity and resolution for the job,” Yan said. “Until these first JWST data sets were published [in mid-July 2022], most astronomers believed that the universe should have very few galaxies beyond redshift 11. At the very least, our results challenge this view. I think this discovery is just the tip of the iceberg because the data we used only focused on a very small area of the universe.After this, I anticipate that other teams of astronomers will find similar results elsewhere in the vast reaches of space soon. As JWST continues to give us new insight into the deepest parts of our universe.” ( Europe Press )