Stockholm University researchers use James Webb Telescope to unveil earliest galaxies through MIRI infrared imaging

This image combines data from the JWST’s MIRI and NIRcam cameras to create a multicolour view of the Hubble Ultra Deep Field. The the green, orange, and red hues come from MIRI and reveal the reddest galaxies and stars in the field. This image was selected as the European Space Agency’s Picture of the Month for August.Credits: ESA/Webb, NASA & CSA, G. Östlin, P. G. Perez-Gonzalez, J. Melinder, the JADES Collaboration, the MIDIS collaboration, M. Zamani (ESA/Webb).

(IN BRIEF) Using the James Webb Space Telescope’s MIRI infrared camera, astronomers including researchers from Stockholm University have observed the earliest galaxies in mid-infrared light for the first time. The study, published in Astronomy and Astrophysics, focuses on the Hubble Ultra Deep Field and reveals how galaxies formed more than 13 billion years ago. MIRI’s long exposures allow scientists to detect older stars, study dust-rich galaxies, and investigate the evolution of supermassive black holes. The results provide crucial insight into early galaxy evolution, and all images and measurements are now publicly available for researchers worldwide.

(PRESS RELEASE) STOCKHOLM, 26-Aug-2025 — /EuropaWire/ — Astronomers using the James Webb Space Telescope (JWST) have, for the first time, captured images of the universe’s earliest galaxies in long-wavelength infrared light. Thanks to the MIRI infrared camera, co-developed by researchers at Stockholm University and Chalmers, scientists can now probe deeper into cosmic history and gain new insight into how galaxies formed more than 13 billion years ago.

The findings, published in Astronomy and Astrophysics, are based on observations of the Hubble Ultra Deep Field (HUDF)—the most intensively studied region of the sky. By combining nearly 100 hours of exposure with MIRI’s sensitivity to mid-infrared wavelengths, the team was able to detect light emitted shortly after the Big Bang, allowing them to study the birth and growth of the first galaxies.

“In the images, we can see the most distant galaxies known to us,” says Göran Östlin, Professor of Astronomy at Stockholm University. “These galaxies emitted their light more than 13 billion years ago, close to the beginning of the universe.”

While previous studies have mainly traced newborn stars, MIRI’s capabilities make it possible to estimate how many stars formed even earlier, offering a clearer view of galaxy evolution during the universe’s formative stages. Jens Melinder, researcher in the Department of Astronomy at Stockholm University, explains: “With MIRI, we can go beyond the youngest stars and measure populations of older stars formed near the Big Bang. This provides crucial clues about how the first galaxies grew.”

The new observations also unlock opportunities to study dusty galaxies and the growth of supermassive black holes. Interstellar dust absorbs starlight at shorter wavelengths, but the mid-infrared light captured by MIRI can penetrate this obscuring material. “MIRI allows us to see through the veil of dust. This helps us understand how heavy elements formed in the early universe, and how black holes surrounded by hot dust evolved,” adds Melinder.

All images and data from this work are now publicly available for researchers worldwide. The team expects the dataset to become a major resource for future studies of galaxy formation. “The HUDF is already one of the most closely examined areas of the sky,” says Melinder. “Making our images accessible means they will serve as a foundation for many more discoveries.”

These observations are part of guaranteed observation time granted to European partners who helped develop MIRI for JWST. At Stockholm University, the work is led by Göran Östlin, alongside Jens Melinder and Arjan Bik of the Department of Astronomy’s Galaxies group, as part of the international MIRI Deep Imaging Survey (MIDIS) conducted by the European Consortium for MIRI (EC-MIRI).

Read more

Find the article, ”MIRI Deep Imaging Survey (MIDIS) of the Hubble Ultra Deep Field: Survey description and early results for the galaxy population detected at 5.6 μm”, in Astronomy and Astrophysics.

Find the images for downloading

Read more about the research in the Galaxy Group at Stockholm University

Learn more about JWST: 

https://esawebb.org
https://webbtelescope.org/home

Media contact:

Press telephone: +46 (0) 8-16 40 90
E-mail: press@su.se

SOURCE: Stockholm University