Dark matter is a mysterious substance that exists in large quantities in the universe, with a ratio of five to one to conventional matter. Previous theories have predicted that dark matter may form smaller clumps. Now, for the first time, Hubble observations have found evidence of these small clumps, adding to the dark matter hypothesis that prevailed at the time.
Dark matter has been a key part of our understanding of the universe since the 1930s, when astronomers discovered that clusters of galaxies were moving in a way that suggested they were much heavier than they should be. Still, finding these things is tricky because it only interacts with normal matter through gravity – meaning we can’t see, hear, smell, or taste them. However, we can see its effects on the surrounding environment, and dark matter is thought to play a vital role in the formation of the universe as we know it.
Because of its powerful gravity, dark matter attracts conventional matter no matter where it is deposited. If enough material gathers at that point, it will eventually become so dense that it collapses, creating a star with heat and pressure. Together, the entire galaxy and cluster of stars are born in huge clouds of dark matter.
The version of this story (currently most widely accepted) relies on the “cold state” of dark matter, where dark matter moves relatively slowly. Although we have a lot of evidence that these huge clouds of dark matter bind galaxies together, the theory also suggests that mysterious dark matter should form smaller clumps. Until now, however, the evidence has not been found.
Researchers at NASA’s Jet Propulsion Laboratory (JPL) and the University of California, Los Angeles (UCLA) have now discovered dark matter clumps of similar mass to passenger aircraft.
“Dark matter is much colder than we are on a smaller scale,” said Anna Nierenberg, director of the Hubble Space Telescope. Astronomers have previously conducted other observations on dark matter theory, but our evidence provides the strongest evidence yet of the small pieces of cold dark matter that still exist. By combining the latest theoretical predictions, statistical tools, and new Hubble observations, we now have more reliable results than ever before. “
To do this, they studied eight types of stars – bright objects formed around black holes that actively absorb dust – using a technique called gravitational lensing. In this case, distant objects are quasars about 10 billion light-years away from us, and the nearest objects are large galaxies about 2 billion light-years away. Galaxies separate light, so each quasar appears four times.
The researchers can then analyze these distortions and compare them with the expected results of removing dark matter effects. In doing so, the team was able to calculate the mass of each small piece of dark matter, which appears to be located between The Earth and the quasars and inside and around the galaxy.
“Imagine that each of these eight galaxies is a giant magnifying glass,” said Daniel Gilman, a researcher on the study. Small dark matter clumps, like small cracks in a magnifying glass, change the brightness and position of the four quasar images compared to whether the glass you want to see is smooth or not. “
The study confirms for the first time a major prediction of cold dark matter theory, the team said. This helps to increase the credibility of the theory and eliminates the need for alternative theories that describe them. It may also help to understand the properties of dark matter particles, which can narrow the range of candidate objects that have been detected directly in an ongoing search.
The study was presented at this week’s meeting of the American Astronomical Society.