Cosmic microwave radiation background. Credits: NASA
See part of the galactic record right here where they formed billions of years ago when the universe was formed through the Big Bang.
In a new study, a team of astronomers led by Haojing Yan at the University of Missouri used data from NASA’s James Webb Space Telescope (JWST) Early Release Observations and discovered 87 galaxies that could be the first known galaxies in the universe.
The finding brings astronomers one step closer to finding out when galaxies first appeared in the universe, some 200-400 million years after the Big Bang, said Yan, associate professor of physics and astronomy at MU and lead author of the paper. study.
A pair of color composite images of the galaxy cluster SMACS 0723-27 and its surrounding area taken by NASA’s James Webb Space Telescope through its Early Release Observations (EROs). A team of astronomers led by Haojing Yan at the University of Missouri used the data from these images to identify objects of interest for study. These include galaxies that could be the earliest known galaxies in the universe, around 200-400 million years after the Big Bang. The location of each object of interest is indicated by one of three differently colored circles (blue, green, or red) on the color images. These colors correspond to the range of redshifts where they were found: high (blue), very high (green), or extremely high (red). Haojing Yan and Bangzheng Sun chart. Photos courtesy of NASA, the European Space Agency, the Canadian Space Agency, and the Space Telescope Science Institute. Credit: University of Missouri.
“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. “Our finding gives us the first indication that many galaxies could have formed in the universe much earlier than previously thought.”
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 an object, such as a galaxy, is at, the further away it is from us.”
Therefore, Yan said that the search for galaxies with very high redshifts gives astronomers a way to construct the early history of the universe.
“The speed of light is finite, so it takes a while for light to travel a distance to reach us,” Yan said. “For example, when we look at the sun, we don’t see it as it looks today, but as it looked about eight minutes ago. That’s because that’s how long it takes for radiation from the sun to arrive. us. So when we’re looking at galaxies that are very far away, we’re looking at their images from a long time ago.”
Using this concept, Yan’s team analyzed the infrared light captured by the JWST to identify the galaxies.
“The greater the redshift of a galaxy, the longer it takes for light to reach us, so a greater redshift corresponds to an earlier view of the universe,” Yan said. “Therefore, by looking at galaxies with higher redshifts, we get earlier snapshots of what the universe looked like a long time ago.”