The search for gravitational waves, the ripples of space and time caused by a major cosmic catastrophe, could help solve another hot mystery in the universe — boson clouds and whether they are a major contender for dark matter. Researchers are using powerful instruments such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), the advanced Virgo, and KAGRA, which can detect gravitational waves billions of light-years away to locate potential boson clouds.
The boson cloud, made up of ultralight subatomic particles that are nearly impossible to detect, is thought to be a possible source of dark matter — dark matter makes up about 85 percent of all matter in the universe.
Now, a new major international study co-led by researchers from the Australian National University (ANU) in the LIGO-Virgo-KAGRA collaboration provides one of the best clues to date about the hunt for these subatomic particles by searching for gravitational waves caused by boson clouds that bypass black holes.
Dr Lilli Sun of the Centre for Gravitational Astrophysics at the Australian National University said the study was the world's first all-space-wide range survey tailored to look for predicted gravitational waves from possible boson clouds near fast-rotating black holes.
"It's almost impossible to detect these ultra-light boson particles on Earth," Dr. Sun said. "Because these particles, if they exist, would be extremely massed and rarely interact with other matter —one of the key properties that dark matter seems to have." Dark matter is matter that cannot be seen directly, but we know that dark matter exists because it has an effect on the objects we can observe.
"But by searching for gravitational waves emitted by these clouds, we may be able to trace these elusive boson particles and potentially crack the code of dark matter." Our search also allows us to exclude certain ultralight boson particles, which our theory says may exist but do not actually exist. "
Dr. Sun is also an associate researcher at arc's Center of Excellence for Gravitational Wave Discovery (OzGrav), where the gravitational wave detector allows researchers to examine the energy extracted by fast-spinning black holes, if they exist.
"We believe these black holes capture a large number of boson particles in their powerful gravitational field, forming a cloud that dances with them." This delicate dance lasted for millions of years and continued to produce gravitational waves that hurried through space. While researchers haven't detected gravitational waves from boson clouds, Dr. Sun says gravitational wave science has "opened doors that were previously locked by scientists."
"The discovery of gravitational waves not only provides information about mysterious compact objects in the universe, such as black holes and neutron stars, they also allow us to look for new particles and dark matter," she said. "Future gravitational wave detectors will certainly open up more possibilities." We will be able to delve deep into the universe and discover more insights into these particles.
"For example, using a gravitational wave detector to discover boson clouds will bring important insights about dark matter and help advance the search for other dark matter." It will also advance our understanding of particle physics more broadly. "
In another major breakthrough, the study also gained a better understanding of the chances of boson clouds existing in our galaxy by considering the age of boson clouds. The strength of any gravitational wave depends on the age of the cloud, and older clouds send weaker signals. Boson clouds shrink when they lose energy by emitting gravitational waves. A particular type of boson cloud of less than 1,000 years old could not exist anywhere in our Galaxy, and a cloud of up to 10 million years old could not exist in the range of about 3260 light-years from Earth.