Dark Matter Interactive Or Not? Behavior Not The Same As Previously Thought

The mystery of dark matter, the unseen, non-luminous material thought to make up nearly a third of the universe, has become deeper than ever, thanks to a discovery contradicting a popular theory regarding the material’s behavior.

Back in 2015, an international team of astronomers reported a major finding as part of their mission to determine dark matter’s real identity. They looked at the observational data from Hubble and found the ghostly material surrounding a galaxy, located some 1.3 billion light-years from Earth, appears to have separated.

Though dark matter cannot be seen, scientists detect signs of its presence by looking at the unusual movement of visible masses, ScienceAlert reported. In this case, the group, led by astronomers from Durham University, found the blob of dark matter trailing.

This led them to posit that the ghostly material might be interacting with a force other than gravity, something that could have been leveraged by scientists to understand what dark matter really is.

However, the same group now posits the distant galaxy is still attached to its pocket of dark matter. They analyzed infra-red distortions from an unrelated galaxy sitting in the background using Chile’s ALMA telescope and obtained the true position of dark matter in high-resolution results.

The view of the neighborhood was better than that of Hubble and helped them pinpoint the exact location of dark matter. "The search for dark matter is frustrating, but that's science. When data improves, the conclusions can change,” lead study author Richard Massey said in a statement.

The idea of interacting dark matter is contradicted with this work, but one cannot rule it out completely. According to the researchers, it is possible that the material is interacting very little or is being displaced sideways, which we might not be able to see if a galaxy is moving directly towards us. "As long as dark matter doesn't interact with the Universe around it, we are having a hard time working out what it is," Massey added.

That said, further studies will be required to understand the properties of the ghostly material to uncover its actual identity. "Different properties of dark matter do leave tell-tale signs,” study co-author Andrew Robertson said in the same statement. "We will keep looking for nature to have done the experiment we need, and for us to see it from the right angle.

"One especially interesting test is that dark matter interactions make clumps of dark matter more spherical. That's the next thing we're going to look for," Robertson concluded. The group has also developed a novel type of telescope, dubbed SuperBIT, to improve their search for dark matter and measure its presence in hundreds of galaxy clusters.

The latest findings from the observation will be detailed in journal Monthly Notices of the Royal Astronomical Society.