Astronomers using ESA’s XMM-Newton and NASA’s Chandra X-ray observatories have observed a 3-million-light-year-long bridge of hot gas linking two unequal mass clusters of galaxies in the very peculiar cluster system Abell 2384; the two clusters collided several hundred million years ago and then passed through each other to arrive in this configuration.
Abell 2384 contains the giant structures that can result when two galaxy clusters collide. A superheated gas bridge is seen in this composite image with X-rays from Chandra and XMM-Newton (blue), radio emission from the Giant Metrewave Radio Telescope (red) and optical data from the Digitized Sky Survey (yellow). This multi-wavelength view reveals the effects of a jet shooting away from a supermassive black hole in the center of a galaxy in one of the clusters. The jet is so powerful that it is bending the shape of the gas bridge, which extends for over 3 million light-years and has the mass of about 6 trillion solar masses. Image credit: NASA / CXC / SAO / V. Parekh et al / ESA / XMM-Newton / NCRA / GMRT.
Abell 2384 is located approximately 1.2 billion light-years away in the constellation of Capricornus.
The system consists of two unequal mass clusters of galaxies: A2384(N) and A2384(S).
Based on previous work, astronomers estimate the total mass of Abell 2384 is 260 trillion solar masses. This includes the dark matter, hot gas and the individual galaxies.
A2384(N) and A2384(S) collided and then passed through each other, releasing a flood of hot gas from each cluster that formed an unusual bridge between the two objects.
The new multi-wavelength view from XMM-Newton and Chandra reveals the effects of a jet shooting away from a supermassive black hole in the center of a galaxy in one of the clusters.
The jet is so powerful that it is bending the shape of the gas bridge, which has a mass equivalent to about six trillion solar masses.
At the collision site, where the jet is pushing the hot gas in the bridge, the astronomers found evidence for a shock front, similar to a sonic boom from a supersonic aircraft, which can keep the gas hot and prevent it from cooling to form new stars.
“Objects like Abell 2384 are important for astronomers to understand the growth of galaxy clusters,” said Dr. Viral Parekh of SARAO and Rhodes University and colleagues.
“Computer simulations indicate that, after such a collision, galaxy clusters oscillate like a pendulum and pass through each other several times before merging to form a larger cluster.”
“Based on these simulations, astronomers think that the two clusters in this system will eventually merge.”
A paper on the findings was published in the Monthly Notices of the Royal Astronomical Society.
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V. Parekh et al. 2020. A rare case of FR I interaction with a hot X-ray bridge in the A2384 galaxy cluster. MNRAS 491 (2): 2605-2616; doi: 10.1093/mnras/stz3067
