These structures could be a source of dark matter. Gravitational wave hunt could bring scientists closer to unraveling potential boson clouds.
Scientists are hunting for gravitational waves with the goal of unlocking one of the Universe’s mysteries: boson clouds. A team of researchers at the Australian National University (ANU) is using gravitational wave detectors, Ligo, Virgo and Kagra, which detect gravitational waves up to billions of light-years away, to identify potential structures made up of ultralight subatomic particles that are nearly impossible to detect.
What are boson clouds
Scientists speculate that boson clouds, if they really exist, may be a source of dark matter, the component believed to make up 85% of all matter in the Universe. Ultralight bosons are particles whose mass is predicted to be less than one billionth the mass of an electron. They interact relatively little with their surroundings and have so far evaded searches. According to the predictions of quantum theory, a black hole of a certain mass should attract clouds of ultralight bosons which, in turn, would slow down the black hole’s rotation by “extracting” energy in a process called super radiance.
The hunt for gravitational waves from boson clouds
The new study starts with the very idea of looking for gravitational waves caused by boson clouds surrounding black holes. Dr. Lilli Sun, of the ANU Centre for Gravitational Astrophysics, explained that the project can be regarded as the first all-sky survey dedicated to looking for gravitational waves from possible boson clouds near rapidly rotating black holes. As Sun explains, it is nearly impossible to discover these particles on Earth because they have very small masses and precisely because of this, they do not interact with other matter. This characteristic, by the way, is the main feature of dark matter.
“By looking for gravitational waves emitted by these clouds,” said the Anu doctor, “we may be able to track down these elusive boson particles and possibly crack the dark matter code. The detectors used allow them to examine the energy of rapidly rotating black holes, and the researchers believe that these black holes trap a great many of these bosons precisely because of their powerful gravitational field.
After capturing the clouds of bosons, a cloud would be created around the black holes that orbits them. “This delicate dance continues for millions of years and generates gravitational waves that hurtle through space,” Sun pointed out. Although the researchers have not yet detected gravitational waves from the boson clouds, the study suggests two new possibilities: gravitational waves provide information about compact objects in the Universe such as black holes and neutron stars, with future gravitational wave detectors we will be able to reach deeper into the Cosmos.
In the meantime, astronomers are also looking for another planet similar to ours, while a black hole has been found in a star cluster.
Stefania Bernardini