New observations and simulations on the Universe indicate that high-energy particle jets emitted in the brightest galaxy from the central massive black hole in galaxy clusters could be used to draw up the structure of invisible magnetic inter-cluster fields. These findings provide astronomers with a new tool to study previously unexplored aspects of galaxy clusters.
As galaxy clusters grow in collisions with the surrounding matter, they cause bow shocks and wake in their diluted plasma. The movements of plasma in the Universe caused by these activities can cover intra-cluster magnetic layers and form virtual magnetic force walls.
However, these magnetic layers can only be seen indirectly if something interacts with them. Because these interactions are simply difficult to identify, the nature of the magnetic fields intracluster is still poorly understood. A new approach is highly desired to map/characterize magnetic layers.
The MeerKAT radio telescope in South Africa’s northern Karoo deserts has been used by an international team of astronomers including Haruka Sakemi, a graduate student of Kyushu University (now a researcher at Japan’s National Astronomy Observatory — NaoJ) to observe a bright galaxy in the Universe Abell 3376 galaxy cluster known as the MRC 0600-399.
It is known that MRC 0600-399 in the Universe, more than 600 million light-years away towards the Columba Constellation, has unusual jet structures at 90-degree angles. Previous X-ray observations show that MRC 0600-399 represents the core of a subcluster that penetrates the principal cluster of the Universe, indicating the presence on the border of the main and subclusters of strong magnetic layers. These features make MRC 0600-399 an ideal laboratory to investigate jet and strong magnetic layer interactions.
The observation by MeerKAT revealed unprecedented jet details, most strikingly a faint ‘double scythe structure extending from the bend points and creating a “T” shape in the opposite direction. These new details show that this is a very chaotic collision, like a stream of water hitting a glass panel. To explain the observed jet morphology and possible magnetic field configurations, dedicated computer simulations are required.
University Take On The Universe
Takumi Ohmura, a graduate student of Kyushu University (now a fellow student of Cosmic-Ray Research Institute, ICRR) performed simulations on NAOJ’s ATERUI II, the most powerful astronomical computer in the world. The Universe simulations assumed a strong magnetic field, which neglected messy details such as turbulence and galaxy movement.
This simple model corresponds well to the observations, indicating that the magnetic pattern used in the simulation reflects the current level and structure of the magnetic field around MRC 0600-399. More importantly, the simulations demonstrate the underlying physics successfully in order to be used on other objects to characterise more complex magnetic field structures in galaxy clusters. This offers astronomers a new way of understanding the magnetised Universe and a tool for analysing higher quality data from future radio observatories such as SKA (the Square Kilometre Array).
The results were presented by Chibueze, Sakemi, Ohmura, and others, “Bent jets from magnetic Universe fields in the Abell 3376 galaxy cluster” in Nature on 6 May 2021.
