A new window to see hidden side of magnetized universe

By | May 20, 2021

New observations and simulations suggest that jets of high-energy particles emitted from a 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 to investigate previously unexplained aspects of clusters of galaxies.

As clusters of galaxies grow as they collide with the surrounding material, they produce bow shocks and wake up in their attenuated plasma. The plasma motion induced by these activities can wrap up intra-cluster magnetic layers, creating virtual walls of magnetic force.

However, these magnetic layers can only be seen indirectly when something interacts with them. Because such interactions are difficult to identify, the nature of the intra-cluster magnetic field is poorly understood. A new approach for mapping / characterization of magnetic layers is highly desired.

An international team of astronomers including Haruka Sakemi, a graduate student at Kyushu University (now a research fellow at Japan’s National Astronomical Observatory-NAOJ), used the Miracat radio telescope located in South Africa’s North Kaoru Desert to observe the bright galaxy .

In the merging galaxy cluster Abell 3376 known as MRC 0600-399. Located more than 400 million light-years away in the direction of the Columba planetarium, MRC0400-37 is known for unusual jet structures, which are bent at a 60-degree angle.

Previous X-ray observations have shown that MRC 0600–399 is the core of the subset entering the main cluster of galaxies, indicating the presence of strong magnetic layers at the boundary between the main and sub-groups. These characteristics make MRC 0600-399 an ideal laboratory for investigating interactions between jets and strong magnetic layers.

The Miracat observations revealed an unprecedented description of the jet, most surprisingly, the faint ‘double-skewth’ structure extending counterclockwise from the turning points and forming a “T” shape. These new details suggest that, as a stream of water collides with the glass pane, it is a very chaotic collision. Dedicated computer simulations are needed to explain the observed jet morphology and possible magnetic field configurations.

Takumi Ohmura, a graduate student from the team at Kyushu University (now a research fellow at the University of Tokyo’s Institute for Cosmic-Ray Research-ICRR), performed simulations on NAOJ’s supercomputer EteruI II, the world’s most powerful computer dedicated to astronomers. Calculation.

The simulation assumed a hardcore-like strong magnetic field, ignoring disturbing details such as turbulence and the motion of the galaxy.

This simple model provides a good match for observations, indicating that the magnetic pattern used in the simulation reflects the intensity and composition of the actual magnetic field around MRC 0600–399. More importantly, it shows that simulations can successfully represent the underlying physics so that they can be used on other objects to characterize more complex magnetic field structures in clusters of galaxies.

It offers astronomers a new way of understanding the magnetic universe and provides a tool to analyze high-quality data from future radio observatories such as SKA (Square Kilometer Array).

These results appeared as Chibuse, Sakemi, Ohmura, et. al. “Bent jet from magnetic field in galaxy cluster Abell 3376” in Nature on May 6, 2021.

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