JWST Provides New Insights into the Evolution of Our Universe

An image of galaxy cluster SMACS 0723 collected by the James Webb telescope (JWST). This is the first deep field image the JWST observatory collected, measuring a section of the universe approximately the size of a grain of sand held at arm’s length. Credit: NASA, ESA, CSA, and STScI.

Infrared telescopes provide insight into galaxy formation and the evolution of our universe. In July 2022, NASA released the first results of the JWST telescope. JWST is the first infrared telescope with the sensitivity and resolution required to study the abundance and composition of the earliest known galaxies in our universe. Within one study alone, Haojing Yan at the University of Missouri and colleagues discovered 87 galaxies forming in a small pocket of the universe within the first 200 to 400 million years after the Big Bang. These galaxies were discovered using redshifts, a measure of how the wavelengths of light emitted from a galaxy are shifted towards the red part of the spectrum as it moves further away from our solar system. Results far exceeded the number of previously predicted and astronomically measured galaxies at this stage in the universe’s evolution.

Hayley Williams at the University of Minnesota and her team discovered the smallest galaxy measured within the first 500 million years after the Big Bang. It was discovered from JWST data using gravitational lensing, a process that bends and magnifies light from surrounding clustering galaxies to increase the brightness of smaller galaxies 20-fold so they can be studied in more detail. This galaxy generated stars at an extremely high rate for its size. Using JWST data, Bo Peng at Cornell University and his team also discovered a galaxy with a metallicity far exceeding what was previously expected at this stage in the evolution of our universe. In astronomy, metallicity refers to the abundance of elements heavier than hydrogen and helium and is increased by previous generations of stars that lived and died. Based on measured molecules, particularly nitrogen/oxygen ratios, the discovered galaxy would have required 8 billion years of build-up from previous generations of stars. Together, these studies indicate that stellar formation is far more efficient than previously thought and occurs at an earlier stage in the evolution of our universe, advancing our understanding of how stars and galaxies formed within our universe. READ MORE: First Batch of z ≈ 11–20 Candidate Objects Revealed by JWST Early Release Observations on SMACS 0723-73, A magnified compact galaxy at redshift 9.51 with strong nebular emission lines, and Discovery of a Dusty, Chemically Mature Companion to a z ∼ 4 Starburst Galaxy in JWST ERS Data.