A team of astronomers led by Haojing Yang of the University of Missouri used early observations from NASA’s James Webb Space Telescope (JWST) and discovered 87 galaxies that may be the oldest known galaxies in the universe. According to Jan, lead author and associate professor in the MU Department of Physics and Astronomy, the discovery brings astronomers closer to determining the origin of galaxies in the universe between 200 and 400 million years after the Big Bang.

“Finding such a large number of galaxies in the early universe suggests that we may need to revise our previous understanding of galaxy formation,” Yang said. “Our discovery gives us the first indication that many galaxies in the universe may have formed much earlier than previously thought.”

In the study, astronomers searched for potential galaxies at “very high redshifts.” The concept of redshift in astronomy allows astronomers to measure how far distant objects in the universe, such as galaxies, are by looking at how the colors change in the light waves they emit, Yang said.

“As the light emitting source moves towards us, the light is ‘squeezed out’ and this shorter wavelength is represented by blue light, or blue shift,” Yang said. “But if it is a resource [світла] As it moves away from us, the light it produces is “stretched” and converted to a longer wavelength, represented by red light, or redshift.”

Yang 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 galaxy are moving away from us and are moving away faster as they move away,” Yang said. “It’s related to redshift because of the concept of distance – the more redshift an object like a galaxy has, the farther it moves away from us.”

That’s why searching for galaxies at very high redshifts gives astronomers a chance to plot the early history of the universe, Yang said.

“Light has a limited speed, so it takes time for light to travel the distance to reach us,” Yang said. Said. “For example, when we look at the sun, we’re not looking at what it looks like now, but how it looked eight minutes ago. That’s because it took so long for solar radiation to reach us. That’s why when we look at galaxies so far away, we’re looking at images of them a long time ago.”

Using this concept, Yan’s team analyzed infrared light captured by JWST to identify galaxies.

“The higher the redshift of a galaxy, the longer it takes for light to reach us, so a higher redshift corresponds to an earlier view of the universe,” Yang said. “So by looking at higher redshift galaxies, we get earlier snapshots of what the universe was like a long time ago.”

JWST was crucial to this discovery because objects in space, such as galaxies at high redshifts (11 or more), can only be detected in infrared light, according to Yan. This is more than the Hubble Space Telescope can detect, because the Hubble telescope can only see from ultraviolet to near-infrared light.

“As the most powerful infrared telescope, JWST has the sensitivity and resolution for the job,” Yang said. “Until these first JWST datasets are published [в середині липня 2022 року], most astronomers believed that there must be very few galaxies in the Universe at a redshift of 11. At the very least, our results challenge this view. I believe this finding is just the tip of the iceberg because the data we use covers a very small part of the universe. From now on, I expect other groups of astronomers to find similar results elsewhere in space as JWST continues to give us new insights into the deepest parts of our universe.”