Image source – NASA
A galaxy cluster is a set of the most extensive cosmic gravitational systems, consisting of three hundred to a thousand galaxies, an enormous volume of highly heated gas, and a large quantity of dark matter. With these cosmic titans, scientists get to know the evolution of galaxies, stars, and black holes, and the expansion of the universe over billions of years of time.The Chandra X-ray Observatory of NASA has examined numerous galaxy clusters. In doing so, it has detected gas with high temperatures even up to 100 million degrees. This hot gas along with the energy from supermassive black holes located at the centres of clusters, is responsible for the production of bubbles, waves, and other strange shapes. To have a better understanding of these shapes, astronomers have invented a new method known as X-arithmetic. This method helps to reveal the true nature of these features that are less obvious from the data by providing a clearer, more efficient way to analyse X-ray data. Hence, it allows astronomers to go deeper into the energetic events that are shaping galaxy clusters.
The massive and mysterious nature of galaxy clusters
Galactic clusters are gigantic cosmic systems with up to a few thousand galaxies each. Their main component is neither the stars nor the galaxies but rather the superheated gas that emits X-ray light. The mass of this hot gas is usually five times that of the galaxies altogether. What is even more surprising is that nearly 80 percent of the total mass of a cluster is that of dark matter, which is an invisible stuff that does not give off light but has a strong gravitational influence.Due to their huge sizes and complicated compositions, galaxy clusters hold essential clues to the universe. They provide astronomers with insights as to how matter accumulates, how galaxies come into being, and how the cosmic structures change over time.
Chandra’s X-ray vision detects hot gas and hidden activities
One of the major contributors to the reveal of galaxy clusters’ secrets has been NASA’s Chandra X-ray Observatory which came into orbit in 1999. Owing to its sophisticated detectors, extremely hot gases whose temperatures reach up to tens of millions of degrees can be detected by the scientists. This gas, which is in between the galaxies, keeps the whole cluster in check by showing the traces of the past events that happened inside it.In fact, there are supermassive black holes at the centres of most galaxy clusters. With these black holes, the black holes can result in situations where powerful outbursts happen, causing the release of jets of high-energy particles. These jets on their way into the surrounding gas, when forced, form large bubbles that expand outward, which is the result. In addition to the bubbles, Chandra has also found that the explosive events have created arcs, rings, hooks, and wing-formed patterns. Although the models of these shapes look very nice, they do not imply that the cause of the shapes is revealed.
New X-Ray technique, X-Arithmetic: decoding the signals
In order to solve this problem, astronomers developed a novel technique named X-arithmetic. This image-processing approach examines X-ray data to a much greater extent than the previous methods. Rather than merely considering the appearances of the structures, X-arithmetic actually specifies their physical basis.The method involves breaking down the X-ray data into two groups of lower-energy and higher-energy bands. They detect the process of creating a certain structure by looking for the one whose strength could be found in either of these sets. Scientists have different colours to indicate each characteristic:
- Pink for sound waves and weak shock fronts
- Yellow for black-hole inflated bubbles
- Blue for the gas that is cooling or is slower-moving
The use of these colours results in a new type of map that shows the cluster is shaped by which different forces.
Scientists are testing the method on the galaxy clusters
Team X-arithmetic worked on 15 galaxy clusters and groups of galaxies. In the new photos set, five of the most famous clusters are displayed: MS 0735+7421 and the Perseus Cluster, and the Virgo Cluster’s M87 on the top row and Cygnus A and Abell 2052 on the bottom row. All of these have been observed before, but this is the first time X-arithmetic has been used on them.By comparing the outcomes with the computer simulations, researchers were able to figure out how the energy flows in these huge systems. This new technique is an instrumental one to use when bridging the gap between theoretical models and observational data.
Learning how black hole outbursts affect surroundings
There is still a lot of mystery around the behaviour of supermassive black holes in galaxy clusters. Questions of how much energy these black holes discharge into the surrounding gas and at what intervals these eruptions happen are what scientists are eager to find out. Such outbursts have a dramatic impact on the cluster: they are the ones that prevent the gas from cooling too fast and help in the regulation of the birth of new stars.The X-arithmetic technique is way ahead in solving this mystery by bringing the scientists to the verge of understanding these events. In unveiling the ultimate reality of the patterns made by black-hole activity, which in turn, gives a more lucid view, this method is undoubtedly a helper in the depiction of the forces that determine the largest objects in the universe. Go to Source