Astronomy|Dark matter was observed to separate from visible matter in a massive cosmic collision.
The summary is made by artificial intelligence and checked by a human.
Researchers have observed the separation of dark matter and visible matter at different rates.
Dark matter flies apart from visible matter in colliding clusters of galaxies.
The observation confirms that dark matter behaves differently than visible matter.
In the dark searching for a particle of matter is like digging for an invisible needle in a haystack.
Of the known forces, it apparently only obeys gravity, with which dark matter has been detected.
Now astronomers have discovered how and at what speed dark matter flies apart from visible matter when two massive galaxy clusters collide. It flies researcher Emily Silichin I said like sand from the truck bed in a sudden stop.
Astrophysicist Silich is the lead author of the study, which he published Astrophysical Journal – science journal. He works at the California Institute of Technology, Caltech.
According to Silich, the result confirms that dark matter behaves differently than visible matter – at least in the sense that it does not slow down in the same way.
In observed galaxy clusters each contain thousands of galaxies. They are billions of light years away from us.
As clusters of galaxies collapse into each other, dark matter appears to race ahead of ordinary matter.
There is more than five times as much dark matter as visible matter in that galaxy cluster.
This is the first observation in which the velocities of dark matter and visible matter have been determined in such a collision, says a university researcher Matti Heikinheimo from the University of Helsinki.
“Such observations help to better understand the collisions of galaxy clusters and the behavior of dark matter in them.”
In the bulletin is an illustrative animation.
Clusters of galaxies are the largest structures in the universe, according to research release describes. The colliding galaxy cluster is found as MACS J0018.5+1626.
Forces are held in check by gravity. But only a small fraction of the observed cluster-like structures is visible matter, and the vast majority of that is hot gas. The rest of the substance is dark.
The individual galaxies in the arrays continue their movement pretty much like a puzzle, because there is a lot of empty space between them. But the collision of clouds of visible hot gas creates large sources of radiation.
The colliding visible matter is slowed down by the electromagnetic force acting between the particles of the visible matter.
Dark matter does not care about the electromagnetic force, so it continues its journey.
A similar disparity between dark matter and visible matter has been observed before.
The so-called Bullet Squad is famous. Even there, the hot gas is left behind, as the dark matter advances from the collision of galaxy clusters.
For researchers the rewarding thing is that one of the observed galaxy clusters flies almost directly towards the Earth and the other correspondingly away.
It helped estimate the velocities of both dark matter and visible matter. However, measurements of the velocities of individual galaxies were used to determine the speed of dark matter, Heikinheimo reminds.
“When you can’t see dark matter, you can’t directly measure its speed either, so the observation is indirect in this sense.”
A cluster of galaxies dark matter was detected using the so-called gravitational lensing effect.
It means that dark matter is detected by the light emitted by visible objects behind it.
The mass of dark matter bends the light coming behind it in certain ways with its gravity. Dark matter exists not only in and around the entire cluster, but also in and around individual galaxies.
The researchers also found that before the collision, the clusters of galaxies were hurtling toward each other at a speed of about 3,000 kilometers per second. So the speed was about one percent of the speed of light.
According to researcher Silich, such collisions are the most powerful events in the universe since the Big Bang.
Fresh the study used data from several observatories.
These include the US Space Administration’s Chandra X-ray telescope and the Hubble telescope, as well as the European Space Agency’s Herschel infrared telescope and the Planck space telescope. Visible light telescopes included, among others, the Keck telescope in Hawaii.
Fact
Dark matter dominates
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There is five times as much dark matter as visible matter. There is only five percent of known matter. If we talk about the mass energy of the entire universe, however, dark matter is only a quarter of it – the vast majority, or 70 percent, is mysterious dark energy.
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The story of dark matter began in the 1930s. Swiss-American astronomer Fritz Zwicky found that galaxies in the distant group were orbiting each other faster than expected based on apparent mass. Perhaps invisible matter increased the mass of galaxies?
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American Vera Rubin and colleagues discovered in the 1960s that the outermost stars of galaxies rotate too fast for the visible mass. Something invisible held the galaxies together with its attraction.
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A possible particle of dark matter is being searched for, among other things, in Italy’s Gran Sasso. Inside the mountain is a detector that contains the noble gas xenon by the ton. If a dark particle collides with a xenon atom, it can emit a measurable photon. There are similar experiments in the United States and China.