Alumni news
Sussex astronomer helps to uncover images of what may be the earliest galaxy ever detected
By: Vicky Trendall Lane
Last updated: Friday, 12 August 2022
A mosaic of 690 individual frames taken with the Near Infrared Camera (NIRCam) on the James Webb Space Telescope
Two incredible new images from NASA’s James Webb Space Telescope (JWST), collected by an expert team that includes a University of Sussex astronomer, show what may be among the earliest galaxies ever observed.
Both images include objects from more than 13 billion years ago, with one offering a much wider field of view than Webb’s First Deep Field image, which was released amid great fanfare on July 12.
One particularly exciting object identified within the new JWST images —dubbed Maisie’s galaxy in honour of project head Steven Finkelstein’s daughter—has been estimated as being observed as it was just 290 million years after the Big Bang (astronomers refer to this as a redshift of z=14).
The images represent some of the first out of a major collaboration of astronomers and other academic researchers teaming with NASA and global partners to uncover new insights about the universe. This includes sole UK co-investigator Dr Stephen Wilkins, a Reader in Astronomy and Public Engagement Fellow at Sussex, whose team is using Cosmic Evolution Early Release Survey (CEERS) data to identify examples of the first stars and galaxies to form in the Universe.
Dr Stephen Wilkins said: “The Cosmic Evolution Early Release Survey (CEERS) is providing one of our first glimpses into the distant Universe with JWST. My team here at Sussex are then not only involved in analysing the CEERS observations but building models - essentially simulated Universes - to help us understand what we’re seeing. Even with just the small amount of data we’ve analysed so far, we’re gaining new insights into how the Universe works and, in particular, how the first stars and galaxies form.
“JWST has been in development for almost 30 years - more than my entire career - so it’s really exhilarating to finally get our hands on the data. Every time new observations come in we are hurriedly analysing them to see if we find anything really unusual or unexpected.”
The unprecedentedly sharp images reveal a flurry of complex galaxies evolving over time—some elegantly mature pinwheels, others blobby toddlers, still others gauzy swirls of do-si-doing neighbours. The large image is a mosaic of 690 individual frames that took about 24 hours to collect using the telescope’s main imager, called the Near Infrared Camera (NIRCam). The second image was taken with the Mid-Infrared Instrument (MIRI), which has a smaller field of view compared to the NIRCam, but operates at much higher spatial resolution than previous mid-infrared telescopes. Both are from a patch of sky near the handle of the Big Dipper, a constellation formally named Ursa Major. This same area of sky was observed previously by the Hubble Space Telescope, as seen in the Extended Groth Strip.
Steven Finkelstein, associate professor of astronomy at The University of Texas at Austin and the principal investigator for the Cosmic Evolution Early Release Science Survey (CEERS), from which these images were taken, said: “It’s amazing to see a point of light from Hubble turn into a whole, beautifully shaped galaxy in these new James Webb images, and other galaxies just pop up out of nowhere.
“High-performance computing power made it possible to combine myriad images and hold the frames in memory at once for processing, resulting in a single beautiful image.”
The finding has been published on the preprint server arXiv and is awaiting publication in a peer-reviewed journal. If the finding is confirmed, it would be one of the earliest galaxies ever observed, and its presence would indicate that galaxies started forming much earlier than many astronomers previously thought.
The entire CEERS program will involve more than 60 hours of telescope time. Much more imaging data will be collected in December, along with spectroscopic measurements of hundreds of distant galaxies.
The CEERS collaboration is composed of 18 co-investigators from 12 Institutions and more than 100 collaborators from the U.S. and nine other countries. CEERS researchers are studying how some of the earliest galaxies formed when the universe was less than 5% of its current age, during a period known as reionization.