Astronomers have unlocked the secrets behind the spectacular collision of two massive clusters of galaxies, showing that dark matter and normal matter can indeed separate during these gigantic events.
Located billions of light years away, these clusters contain thousands of galaxies and provide deep insight into the complexity of the universe.
When they collide, dark matter, an invisible substance that is affected by gravity but not light, moves ahead of normal matter. Contains gas and stars.
What does this mean for our understanding of the structure of the universe?
As we delve deeper into these phenomena, we also uncover broader implications that could transform our understanding not only of how the universe works, but also how it interacts and relates to the natural world.
Dark matter and galaxy clusters
Galaxy cluster It’s a vast cosmic structure held together by gravity. Only 15% of its mass is normal matter – mainly hot gas, stars and planets – and the remaining 85% is dark matter.
When the clusters of galaxies, collectively known as MACS J0018.5+1626, collided, the galaxies themselves suffered little damage due to the vast space between them.
but, Galaxies CollidedDark matter and normal matter are both affected by gravity, but normal matter also interacts with it via electromagnetism, slowing it down during collisions.
As a result, dark matter separated from normal matter and moved forward.
“Dark matter is Sand and flies ahead” said lead author Emily Silich, a graduate student working with Professor Jack Sayers. California Institute of Technology The principal investigator of this study.
MACS J0018.5 is a treasure trove
A similar separation of dark matter and normal matter has been observed previously in the Bullet Cluster. The MACS J0018.5 collision was different and offered a unique perspective.
“Using Bullet Cluster is like sitting in the stands watching a car race,” says Sayers, “but it’s like standing in front of a car on a straight stretch of road with a radar gun and being able to measure its speed.”
To measure the velocity of the gas inside the cluster, the researchers used the kinetic Sunyaev-Zel’dovich (SZ) effect.
This effect occurs when photons from the cosmic microwave background scatter off electrons in hot gas, Doppler shiftBy measuring this change, scientists can Gas cloud Within a galaxy cluster.
“When Jack and I first aimed our new camera at galaxy clusters at CSO in 2006, the Sunyaev-Zel’dovich effect was still a very new observational tool,” says Sunil Golwala, professor of physics and Silic’s doctoral supervisor.
“We look forward to seeing many new surprises when we install the next generation of instruments on the telescope at its new home in Chile.”
Normal matter and dark matter separate into clusters
By 2019, researchers had used the kinetic SZ effect to measure the gas velocity in several galaxy clusters and used Keck Observatory data to determine the velocity of galaxies, which also indicates the speed of dark matter.
But researchers noticed an anomaly in MACS J0018.5: hot gas was moving in the opposite direction to the dark matter. Initially, they thought it might be a data error.
“It was a totally bizarre situation with speeds going in opposite directions,” Sayers explains, “and Emily stepped in and sorted it all out.”
Cilic said, Chandra X-ray Observatory “These cluster collisions are the most energetic events since the Big Bang,” she said.
The team also collaborated with Adi Zitrin, Ben-Gurion University of the Negev With John Zuhoorn in Israel to map dark matter using gravitational lensing Harvard-Smithsonian Center for Astrophysics Simulates a cluster collision.
Cluster collisions and the discovery of dark matter
The researchers found that before the collision, the clusters were moving towards each other at speeds of around 3,000 kilometres per second.
The direction of the collision and the separation of dark and normal matter explained the strange speed measurements.
This research provides a new way to directly probe the behavior of dark matter and Mysterious Nature.
“This work is a starting point for more detailed studies of the properties of dark matter,” Šilić said. “We now have a new type of direct probe that shows us how dark matter behaves differently from ordinary matter.”
Further research like this in the future may reveal further clues about dark matter and help scientists understand how such a mysterious substance interacts with the universe. universe.
The discovery used data from several observatories, including Caltech’s Submillimeter Wave Observatory, W. M. Keck Observatory, NASA’s Chandra X-ray Observatory, Hubble Space Telescope, the European Space Agency’s Herschel Space Telescope, and Chile’s Atacama Submillimeter Telescope Experiment. Some of the data was collected decades ago, and the full analysis was carried out over the last few years.
This study Astrophysical Journal.
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