Astronomers using NASA’s James Webb Space Telescope have discovered dozens of small galaxies that played a significant role in transforming the early universe into what we see today. These tiny galaxies, which are rare today but were abundant 800 million years ago, were responsible for producing ultraviolet light that drove this cosmic renovation.
The study analyzed existing imaging data from Webb’s Near-Infrared Camera (NIRCam) and new observations made with its Near-Infrared Spectrograph (NIRSpec). The team identified 83 small starburst galaxies in the giant galaxy cluster Abell 2744, which is located about 4 billion light-years away.
These galaxies are so small that to build the equivalent stellar mass of our Milky Way galaxy, you’d need between 2,000 to 200,000 of them. However, the team was able to detect them using a novel sample selection technique combined with gravitational lensing.
The discovery suggests that these low-mass starburst galaxies could account for all the ultraviolet light needed to convert neutral hydrogen gas into its ionized form, which is a key milestone in the history of the universe known as reionization. This transformation occurred about 800 million years ago, and it’s believed that small galaxies played an outsized role in this process.
The study’s findings provide new insights into the early universe and shed light on the types of objects responsible for reionization. With its advanced instrumentation and precision observations, NASA’s James Webb Space Telescope is solving mysteries about our solar system, distant worlds, and the origins of our universe.
Source: https://science.nasa.gov/missions/webb/nasas-webb-uncovers-galaxy-population-driving-cosmic-renovation