The James Webb Space Telescope (JWST) is a space telescope primarily developed for infrared astronomy. As the largest optical telescope in orbit, its excellent infrared resolution and sensitivity allow it to see objects that the Hubble Space Telescope cannot see because they are too early, far away or faint. This is planned to allow a wide range of astronomical and cosmological investigations, such as the detection of the first stars and the development of the first galaxies, as well as a thorough atmospheric characterization of possibly habitable exoplanets.
Webb’s photographs show a plethora of glittering galaxies in the distant cosmos, appearing just a few hundred million years after the Big Bang, 13.8 billion years ago. Astronomers’ beliefs about the early Universe have been challenged by the extraordinarily sharp images from the telescope.
“We had in mind an idea of what the galaxies at these [distances] would look like and how much detail we would be able to see, but I think the reality is just a bit mind-boggling,” says Jeyhan Kartaltepe, an astronomer at the Rochester Institute of Technology in New York.
Here are some of the things astronomers learned from Webb’s early observations
There are a lot of galaxies out there
Because Webb detects infrared light and because the expanding cosmos expands light to redder wavelengths, it is best suited for detecting galaxies that formed early in the history of the Earth. Universe. Webb detected several distant galaxies that are beyond the reach of other observatories, such as the Hubble Space Telescope, in its initial observing program, which began in June.
The age of the first galaxies began about 250 million years after the Big Bang, when the first stars emerged and illuminated the Universe. Later generations of stars turned into galaxies, which are the dark red spots Webb now discovers. Many of Webb’s photos contain previously unseen galaxies in the distant Universe. “There is almost no free space where there is nothing,” explains Kartaltepe.
One study reviewed data from many distant Webb galaxy fields to determine the rate at which stars were created in the early Universe. He discovered 44 previously unknown galaxies dating back 300 million years after the Big Bang. The observations, when combined with 11 previously known galaxies, suggest that there was a huge population of star-generating galaxies in the early Universe1. The results “reaffirm the great promise of greater [Webb] programs to alter our understanding of the young Universe,” wrote the researchers, led by Callum Donnan of the University of Edinburgh, in a report posted on the arXiv preprint server.
Many galaxies compete for the title of “farthest”
Perhaps the most visible rush is the rush of research teams rushing to discover the most distant galaxy in the Webb data. A number of contenders have been identified that will need to be confirmed by further research, but all would break Hubble’s record for the most distant galaxy, which dates back around 400 million years after the Big Bang.
A competitor surfaced in a Webb scan called GLASS, which also included another galaxy a little less distant. “The discovery of these two bright galaxies was a real surprise,” says Marco Castellano, an astronomer at the National Institute of Astrophysics in Rome. He and his colleagues did not expect to find such distant galaxies in such a small area of the sky. A second team discovered the two galaxies independently.
Some early galaxies are surprisingly complex
The distant Webb galaxies also reveal more complexity than astronomers had expected. A survey of Webb’s first deep-field image discovered a surprisingly large number of distant galaxies with disc-like shapes9. Using Hubble, astronomers discovered that distant galaxies are more irregularly shaped than closer galaxies, which, like the Milky Way, have uniform disc-like shapes. According to this notion, early galaxies were more frequently distorted by interactions with neighboring galaxies. The Webb data, on the other hand, shows that there are up to ten times more distant disc-shaped galaxies than previously thought.
Another preprint manuscript argues that huge galaxies appeared earlier in the history of the Universe than previously thought. A team led by Ivo Labbé of Swinburne University of Technology in Melbourne, Australia, reports finding seven large galaxies with redshifts ranging from 7 to 10. The scientists write: “We infer that the central areas at least some huge galaxies were already largely in place 500 million years after the Big Bang, and this massive galaxy formation began very early in the history of the Universe.
Nearer galaxies are smaller than expected
Webb’s surprises continue much later in the evolution of the Universe. One study looked at Webb’s findings about “cosmic noon,” which happened about three billion years after the Big Bang. This is when the Universe’s star creation peaked and the most light was produced. Wren Suess, an astronomer at the University of California, Santa Cruz, examined Hubble and Webb photographs of galaxies around cosmic noon. Most large galaxies appeared significantly smaller in Webb’s infrared wavelengths than in Hubble12 images. “It has the potential to revolutionize our entire understanding of how the size of galaxies changes over time,” says Suess. Hubble’s surveys found that galaxies start out small and grow larger over time, but Webb’s findings suggest Hubble didn’t have the full picture and that galactic evolution may be more complex than astronomers thought.