NASA’s James Webb Space Telescope (JWST) has provided new insights into the early universe, revealing young galaxies with elongated shapes that challenge current cosmological models. The findings could have significant implications for understanding dark matter, the invisible substance that makes up most of the universe’s mass.
A study published in Nature Astronomy describes how these unusual galaxy forms may offer clues about the true nature of dark matter. The research was led by Álvaro Pozo of the Donostia International Physics Center and included Rogier Windhorst, a Regents Professor at Arizona State University (ASU).
“In the expanding universe defined by Einstein’s theory of general relativity, galaxies grow over time from small clumps of dark matter that form the first star clusters and assemble into larger galaxies via their collective gravity,” said Windhorst, who is also an interdisciplinary scientist for JWST.
“But now Webb suggests that the earliest galaxies may be embedded in marked filamentary structures, which — unlike cold, dark matter — smoothly join the star-forming regions together, more akin to what is expected if dark matter is an ultralight particle that also shows quantum behavior.”
The team used simulations to explore how different types of dark matter—cold, warm, and wave—might influence galaxy formation. While previous models based on cold dark matter struggled to reproduce the observed elongation in JWST images, simulations using warm and wave dark matter showed better alignment with observations.
“If ultralight axion particles make up the dark matter, their quantum wave-like behavior would prevent physical scales smaller than a few light-years to form for a while, contributing to the smooth filamentary behavior that JWST now sees at very large distances,” Pozo explained.
The research team included experts from MIT, Harvard, and Taipei. They found that elongated young galaxies are produced abundantly in both warm and wave dark matter scenarios due to smoother cosmic filaments. Gas and stars flow along these filaments, resulting in prolate galaxy shapes.
Future JWST observations and larger simulation volumes could further test these findings and help clarify the nature of dark matter.
The paper is dedicated to George F. Smoot, whose work contributed significantly to this field before his recent passing. “In connection with the new research, the team would like to highlight that Smoot was among the first to take the light axion interpretation seriously. More broadly, he inspired all of his colleagues through the breadth and depth of his understanding and his unwavering pursuit of fundamental questions across the entire field. This commitment is evident in his ongoing development of quantum detectors for astronomy, as well as his theoretical applications of general relativity to interpret gravitational wave events and understand the nature of dark matter.”
Arizona State University continues its involvement in major scientific advancements such as this study. The university has been recognized for its innovation efforts for eight consecutive years by U.S. News & World Report; it was also ranked highly in undergraduate business, nursing, and engineering programs (https://news.asu.edu/20220911-university-news-asu-no-1-innovation-us-news-world-report-eighth-year?utm_source=twitter&utm_medium=asu&utm_campaign=ASURankings&utm_term=USNWR).
This release was written by Donostia International Physics Center press team with contributions from Kim Baptista at ASU’s School of Earth and Space Exploration.
