“Gravitational waves will bring us exquisitely accurate maps of black holes – maps of their space-time. Those maps will make it crystal clear whether or not what we’re dealing with are black holes as described by general relativity,” said Nobel Prize laureate, Caltech’s Kip Thorne Scientists at Cardiff University’s Gravity Exploration Institute are using the technologies behind one of the biggest scientific breakthroughs of the century—the detection of gravitational waves led by Thorne— in the long-standing search for dark matter.
Scientists believe that the existing gravitational waves technology can finally uncover the exotic, mysterious material. This is despite having extremely sensitive detectors, as demonstrated by several exceptional discoveries. The gravitational wave observatories might finally be able to discover the origin of dark matter, one of the greatest unsolved mysteries of modern physics.
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Laser Interferometers
In a Study The Cardiff team published their first step in this direction in Nature. They used the instruments known as laser interferometers to find a new type of dark matter. It was believed that dark matter contained heavy elementary particles. This belief was not confirmed until recently. Despite numerous efforts, these were not found. Scientists are now exploring alternative theories to explain dark material.
The Scalar Field
According to a recent theory, dark matter could actually be something called a Scalar Field. This would act like invisible waves that penetrate all galaxies including our Milky Way. The scalar fields hypothesis suggests that ultralight dark material behaves more like waves and particles than normal matter, although it may not interact with any matter other than gravity. “We realized our instruments could be used to hunt for this new kind of dark matter, although they were initially designed for detecting gravitational waves,”‘ said professor Hartmut Grote, from Cardiff University’s Gravity Exploration Institute, who led the investigation.
“We have ruled out scalar field dark matter in some mass ranges and for a coupling constant that is six orders of magnitude smaller than had been ruled out by previous experiments,” Grote told The Daily Galaxy “To explain: we searched for a particular type of dark matter, named scalar field dark matter, which now has been constrained a bit more than by previous searches. It is a piece in the big puzzle of dark matter.”
Two beams of light are bounced around between mirrors in a laser interferometer before reaching a detector. Scientists can then determine how out of sync two beams of light with each other. This is a proxy for any disturbances the beams encounter.
The Laser Interferometer Gravitational Wave Observatory – LIGO consists of two interferometers located in the US, each with two 4 km long arms arranged in the shape of an “L,” which were used to detect gravitational waves for the very first time in 2015, and many Since then, it has been many times.
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Grote was the lead scientist for GEO 600 in Germany and UK. It is a highly sensitive interferometer that was used to develop many of the technologies needed to detect gravitational wave detection. In this study, the GE0600 detector was used to specifically search for dark matter. “Scalar field dark matter waves would pass right through the Earth and our instruments, but as they do so, would cause objects such as mirrors to vibrate ever so slightly,”‘ said lead investigator Sander Vermeulen, also from Cardiff University’s Gravity Exploration Institute.
“Vibrations of mirrors would disturb the beams of light in instruments like GEO600 or the LIGO detectors in a particular way characteristic of dark matter, which is something we should be able to detect, depending on the exact properties of that dark matter,” says Vermeulen.
Although dark matter has never been found, scientists believe it exists because of its gravitational influence on all objects. One example is that a large amount dark matter could be responsible for galaxies rotating as they do.
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Important First Strides
Although the team was unsuccessful in detecting dark matter in this study, they claim they have made important first steps in introducing this technology to dark material searches. They also say they have made significant progress in narrowing down certain parameters and are now ready for further studies. “I was surprised by how sensitive an instrument can be for hunting dark matter when it was built for an entirely different purpose originally,” continued Grote.
“We have definitively ruled out some theories that say dark matter has certain properties, so future searches now have a better idea of what to look for,” said Vermeulen. “We believe these new techniques have the true potential to discover dark matter at some point in the future.”
New yet-to-be-built experiments for detecting dark matter therefore need to be designed to be sensitive to dark matter with a different mass or a weaker coupling strength if they are to have any hope of making a detection.”
The Last Word
“We have shown that – given a certain range of possible masses of the dark matter- the interactions between dark matter and normal matter are much weaker than the previously known upper limit,” wrote Vermeulenas a reply to an e-mail The Daily GalaxyIt is now time to ask what dark-matter property were ruled out. “This result,” he notes, “thus rules out the existence of any dark matter with a mass in a certain range and with a certain coupling strength. New yet-to-be-built experiments for detecting dark matter therefore need to be designed to be sensitive to dark matter with a different mass or a weaker coupling strength if they are to have any hope of making a detection.”
Source: Sander M.Vermeulen and co-authors, Direct limits for scalar fields dark matter using a gravitational wave detectorNature (2021). DOI: 10.1038/s41586-021-04031-y
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Maxwell Moe, astrophysicist, NASA Einstein Fellow, University of Arizona via Hartmut Grote, Sander Vermeulen, Cardiff University Nature
Maxwell Moe (astrophysicist, NASA Einstein Fellow University of Arizona), Maxwell Moe Max is usually found at Kitt Peak National Observatory on two nights per week exploring the mysteries and possibilities of the Universe. Max received his Ph.D. from Harvard University in 2015.
