James Webb Finds Earliest Galaxies To Date; Here’s How It Was Done

Photo Credit: NASA, ESA, CSA, and M. Zamani

James Webb Space Telescope was designed to observe the farthest reaches of the universe. Among other duties, the telescope has been created to peep into the past and hunt for early galaxies. Now, new research has confirmed that the space telescope has identified some of the oldest galaxies to date, estimated at 13.4 billion years old.

The research is currently at a nascent stage, which means it is yet to be peer-reviewed, but it offers an indication of what kind of discoveries James Webb is capable of making. The data used for the research came from the JWST Advanced Deep Extragalactic Survey (JADES), which observes the same area of the sky that the Hubble telescope captured in its Ultra Deep Field.

How Did JWST Find These Galaxies?

The reason for observing the same area of the sky imaged by the Hubble telescope is to allow researchers with an aim to identify galaxies that can be observed in Webb’s infrared range but will go unnoticed in Hubble’s optical range. This shows that galaxies are redshifted highly, which means their light is shifted to the redder end of the spectrum because of the universe’s expansion. As the principles of astronomy state, the higher the redshift, the older the galaxy.

This is how astronomers managed to find the oldest galaxies visible in a deep-field image. However, they will have to confirm the findings as it’s possible for younger galaxies to appear much older than they really are.

Spectroscopy Making A Difference

This is where the new research comes into the picture, as it leveraged spectroscopy to break down the light coming from these early galaxies into different wavelengths. This provides a different signature for each galaxy, allowing the scientists to confirm that it is actually an early galaxy.

From the galaxies discovered so far, new research has confirmed that four of them have a redshift of above 10, while two of them have a redshift of more than 13. This means these oldest galaxies belong to a time when the universe was less than 400 million years old.

“For the first time, we have discovered galaxies only 350 million years after the big bang, and we can be absolutely confident of their fantastic distances,” said co-author Brant Robertson. “To find these early galaxies in such stunningly beautiful images is a special experience.”