Astronomers Innovate Search for Dark Matter Using Distant Galaxies

Astronomers are pursuing new avenues to uncover the elusive nature of dark matter, theorized to make up approximately 80% of the Universe’s mass. This mysterious substance does not interact with light in a detectable manner, leading scientists to propose various candidates over the decades, including Weakly-Interacting Massive Particles (WIMPs) and primordial black holes. A recent study led by Oleg Ruchayskiy, an Associate Professor at the University of Copenhagen, suggests a novel approach by utilizing distant galaxies and their active galactic nuclei (AGN) to potentially identify a particle known as the axion.

The concept of dark matter dates back to the 1960s, yet the quest for its particle counterpart has not yielded conclusive results. In the latest research published in Nature Astronomy, Ruchayskiy and his team propose a method that capitalizes on the electromagnetic radiation emitted from AGNs, which are powered by supermassive black holes (SMBH) located at the centers of galaxies. By observing how this radiation interacts with the magnetic fields of intervening galaxy clusters, researchers hope to glean insights into the production of axions, a leading theoretical candidate for dark matter.

Utilizing Cosmological Phenomena as Particle Accelerators

Typically, research into elementary particles is conducted using large particle accelerators, such as the European Organization for Nuclear Research’s (CERN) Large Hadron Collider (LHC) in Geneva. These facilities, while groundbreaking, are expensive and require significant time to construct. As a result, scientists have begun to explore the use of natural cosmic phenomena as alternative particle accelerators. This includes neutron stars, black holes, and now AGNs, as proposed by Ruchayskiy and his colleagues.

In their innovative study, the team focused on 32 SMBHs in distant galaxies, which became visible through the gravitational lensing effects of galaxy clusters in the foreground. This technique allowed them to gather crucial data, ultimately revealing a pattern that may signify the presence of axion-like particles (ALPs). Ruchayskiy explained, “The combined data indicated the presence of gamma rays, which would, in theory, be released by the production of axions.” While this finding does not serve as definitive proof of axions, it narrows the search for the particle associated with dark matter.

The research also opens doors for future investigations into other types of radiation, such as X-rays, which could further illuminate the properties of dark matter. Postdoctoral researcher Lidiia Zadorozhna, a Marie Curie fellow at the Niels Bohr Institute and a leading author of the study, emphasized the importance of this work in advancing the understanding of dark matter’s fundamental nature.

Through their innovative approach, the team at the University of Copenhagen is not only enhancing the search for dark matter but also pushing the boundaries of astrophysical research. By harnessing the vastness of the Universe as a natural laboratory, they are paving the way for potential breakthroughs in one of the most profound mysteries of modern science.