Last September, the James Webb Space Telescope (JWST) made a significant discovery of an ancient galaxy called JWST-ER1g, which formed when the universe was only a quarter of its current age. This galaxy is associated with an Einstein ring created through strong gravitational lensing, where light from a distant source is bent by the galaxy, resulting in a ring-like appearance. The mass within the Einstein radius of JWST-ER1g consists of both stellar and dark matter components. The dark matter mass within the radius was found to be higher than expected, leading researchers to offer possible explanations for this discrepancy.
The dark matter halo surrounding galaxies like JWST-ER1g is comprised of invisible matter that permeates and surrounds the galaxy. Although dark matter has not been directly detected in laboratories, physicists believe it makes up a significant portion of the universe’s matter, about 85%. Researchers at the University of California, Riverside conducted numerical studies to explore the high dark matter density in JWST-ER1g. They proposed that as ordinary matter collapses and condenses into the dark matter halo, it compresses the halo, leading to a higher density of dark matter mass in the same volume.
Daneng Yang, a postdoctoral researcher at UCR and co-author of the study, highlighted the unique opportunities presented by JWST-ER1g for learning about dark matter. The perfect Einstein ring observed in this strong gravitational lensing object allows for valuable insights into the total mass within the Einstein radius, which is crucial for testing dark matter properties. JWST, launched on Christmas Day in 2021, is an orbiting infrared observatory designed to explore the universe and answer fundamental questions. As the largest and most powerful space telescope ever built, JWST is expected to reveal more surprises and contribute to a deeper understanding of dark matter in the future.
Hai-Bo Yu, a professor at UCR, emphasized the unprecedented opportunity provided by JWST to observe ancient galaxies that formed in the early universe. With continued observations and data collection from JWST, researchers hope to uncover more about the origins of galaxies, dark matter, and the evolution of the universe. The study on JWST-ER1g was supported by the John Templeton Foundation and the U.S. Department of Energy. Titled “Cold Dark Matter and Self-interacting Dark Matter Interpretations of the Strong Gravitational Lensing Object JWST-ER1,” the research paper delves into the interpretations of JWST-ER1g and the implications for understanding dark matter properties. Through innovative techniques and cutting-edge observational tools like JWST, scientists are poised to make significant advancements in our knowledge of the universe and its fundamental components.
