New observations and simulations show that jets of high-energy particles emitted from the central massive black hole in the brightest galaxy in galaxy clusters can be used to map the structure of invisible inter-cluster magnetic fields. These findings provide astronomers with a new tool for investigating previously unexplored aspects of clusters of galaxies.

As clusters of galaxies grow through collisions with surrounding matter, they create bow shocks and wakes in their dilute plasma. The plasma motion induced by these activities can drape intra-cluster magnetic layers, forming virtual walls of magnetic force. These magnetic layers, however, can only be observed indirectly when something interacts with them. Because it is simply difficult to identify such interactions, the nature of intra-cluster magnetic fields remains poorly understood. A new approach to map/characterize magnetic layers is highly desired.

New observations and simulations show that jets of high-energy particles emitted from the central massive black hole in the brightest galaxy in galaxy clusters can be used to map the structure of invisible inter-cluster magnetic fields. These findings provide astronomers with a new tool for investigating previously unexplored aspects of clusters of galaxies.

As clusters of galaxies grow through collisions with surrounding matter, they create bow shocks and wakes in their dilute plasma. The plasma motion induced by these activities can drape intra–cluster magnetic layers, forming virtual walls of magnetic force. These magnetic layers, however, can only be observed indirectly when something interacts with them. Because it is simply difficult to identify such interactions, the nature of intra-cluster magnetic fields remains poorly understood. A new approach to map/characterize magnetic layers is highly desired.

An international team of astronomers including Haruka Sakemi, a graduate student at Kyushu University (now a research fellow at the National Astronomical Observatory of Japan—NAOJ), used the MeerKAT radio telescope located in the Northern Karoo desert of South Africa to observe a bright galaxy in the merging galaxy cluster Abell 3376 known as MRC 0600–399. Located more than 600 million light-years away in the direction of the constellation Columba, MRC 0600–399 is known to have unusual jet structures bent to 90-degree angles. Previous X-ray observations revealed that MRC 0600–399 is the core of a sub-cluster penetrating the main cluster of galaxies, indicating the presence of strong magnetic layers at the boundary between the main and sub-clusters. These features make MRC 0600–399 an ideal laboratory to investigate interactions between jets and strong magnetic layers.

Scientists are certain that dark matter exists. Yet, after more than 50 years of searching, they still have no direct evidence for the mysterious substance.

University of Delaware’s Swati Singh is among a small group of researchers across the dark matter community that have begun to wonder if they are looking for the right type of dark matter.

“What if dark matter is much lighter than what traditional particle physics experiments are looking for?” said Singh, an assistant professor of electrical and computer engineering at UD.

The detection of the axion would mark a key episode in the history of science. This hypothetical particle could resolve two fundamental problems of Modern Physics at the same time: the problem of Charge and Parity in the strong interaction, and the mystery of dark matter. However, in spite of the high scientific interest in finding it, the search at high radio frequency-above 6 GHz-has been almost left aside for the lack of the high sensitivity technology which could be built at reasonable cost. Until now.

The Instituto de Astrofísica de Canarias (IAC) will participate in an international collaboration to develop the DALI (Dark-photons & Axion-Like particles Interferometer) experiment, an astro-particle telescope for dark matter whose scientific objective is the search for axions and paraphotons in the 6 to 60 GHz band. The prototype, proof of concept, is currently in the design and fabrication phase at the IAC. The white-paper describing the experiment has been accepted for publication in the Journal of Cosmology and Astroparticle Physics (JCAP).

Predicted by theory in the 1970’s, the axion is a hypothetical low mass particle that interacts weakly with standard particles such as nucleons and electrons, as well as with photons. These proposed interactions are studied to try to detect the axion with different types of instruments. One promising technique is to study the interaction of axions with standard photons.