The most distant galaxy discovered by Edinburgh astronomers

Observations from the James Webb Space Telescope have revealed the most distant galaxy so far.

A team of astronomers led by the University of Edinburgh have discovered what they believe is the most distant galaxy ever observed.

The galaxy has a redshift of 16.7. Redshift is used to measure distances in the cosmos, and describes the way light coming from an object has been stretched by the expansion of the universe to redder wavelengths. The higher the redshift number, the more distant it is and the earlier it is being viewed in cosmic history.

The galaxy discovered is called CEERS-93316, and is 35 billion light-years away.  It is taken from a project called the Cosmic Evolution Early Release Science (CEERS) Survey which is taking some of the first observations with the James Webb Space Telescope (JWST).

The colour image of CEERS-93316, recently featured by BBC News, was made by Edinburgh undergraduate physics students Sophie Jewell and Clara Pollock, who are undertaking summer projects in the Institute for Astronomy, funded by summer studentship bursaries from the School of Physics and Astronomy.

The same team have also published an analysis of the first spectroscopic data from the JWST, led by Leverhulme Fellow Adam Carnall. This work confirms the vast potential of JWST spectroscopy for performing detailed studies of the earliest galaxies, such as CEERS-93316. This work was recently reported on by Science News.

James Webb Space Telescope (JWST)

The JWST is the successor to the Hubble Space Telescope, was launched in December 2021 and first collected images from its home at the second Sun-Earth Lagrange point in June 2022. JWST observations will include the first stars, formation of the first galaxies, our own solar system, and will tell us more about the atmospheres of potentially habitable exoplanets.

PhD student Callum Donnan who is based in the Institute for Astronomy and involved in the project commented: “We’re using a telescope that was designed to do precisely this kind of thing, and it’s amazing.”

Next steps

Observations from the JWST have yet to undergo full spectroscopic examination.  This process will reveal the spectra of galaxies and will explain how the light (originally visible wavelengths) has been stretched into the infrared.  The spectroscopy will also reveal the chemical composition of objects.

Callum Donnan explains: “We can look at the colours in our galaxy in a broad sense, and it’s quite blue, which suggests a younger stellar population. But it’s not blue enough that this galaxy is made up of metal-free stars”.

The discovery by the Edinburgh team will be short lived however – astronomers expect to find ever more distant objects via the images from the JWST over the coming weeks, months and years.