Using observations from the Chandra X-ray Observatory, a researcher from the University of Alabama in Huntsville has discovered a merger shock that was produced by galaxy clusters that is second in strength only to the Bullet Cluster shockwave.
Sarthak Dasadia, a UAH doctoral student advised by assistant physics professor Dr. Ming Sun, located the new shockwave in the merging galaxy cluster Abell 665, according to research that was published in a recent edition of the Astrophysical Journal Letters.
This extremely strong shock zips along at speeds of 2,700 kilometers per second (more than 1,650 miles per second), or three times the local speed of sound in the cluster. To put that into perspective, the fastest-ever manmade object, NASA’s Juno spacecraft, has a peak velocity of just 40 km/second, or less than 25 miles per second, the study authors explained.
“Studying mergers of galaxy clusters has proven to be crucial to our understanding of how such large scale objects form and evolve,” Dasadia said in a statement, adding that his research “could open a door, where people can do a number of different studies based on what I have found.”
Energy produced, movement of gas among measurements collected
Dasadia’s study, which was accepted for publication in just 10 days, sheds light on a shock that could present scientists with an opportunity to analyze high-energy phenomena in the hot plasma located between galaxies (also known as the intra-cluster medium). The UAH student noted that some experts are already using these shocks in order to study the elusive dark matter.
According to the study author, there are two kinds of galaxy clusters in the universe: those that are relaxes, which have been around far longer and are less dynamically active, and those which are unrelaxed, which are prime targets for scientists looking to observe merger features, such as shocks and turbulence. Abell 665 is the latter type of cluster, he said.
“These galaxy clusters are not boundary objects. They do not have a very well-defined boundary around them,” he said. When these poorly defined boundaries begin the slow process of colliding into one another, their cold cores collide, which can create a shockwaves of heated gas in what is among the most energetic events in the universe, behind only to the Big Bang, Dasadia noted.
These occurrences are not dissimilar to the weather events we experience on Earth, according to the UAH researcher. The physics are similar, and the same types of features (fronts, shockwaves and temperature differences) play key roles in the observed phenomena. As part of his work, he explained that he was able to measure the velocity of the collision and observed the events which occurred in them 3.2 billion years ago (the length of time it took the light to travel here).
Among the observations he collected was the amount of energy produced by the collision, the movement of the gas, and measurements of the discrepancy between the visible and dark matter involved. Dasadia said that he was “amazed” by “how long it takes for this information to even reach the Earth” and by the degree to which “we have advanced in developing the telescopes and equipment it takes to be able to observe and study these interactions.”
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Image credit: Chandra X-ray Observatory
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