Scientists have discovered a novel method to uncover the mysterious nature of dark matter using gravitational wave detectors like LIGO. This promising approach could shed light on one of the biggest unsolved mysteries in astrophysics.
Finding the ‘dark’ force behind weakly interacting massive particles
For decades, dark matter has confounded scientists at every turn. The elusive substance accounts for much of the universe’s mass but cannot be observed directly. Dark matter, on the other hand, enjoys a kind of stealth. It doesn’t absorb light; it doesn’t reflect light; and it doesn’t emit light (it remains quasi-invisible to conventional observation).
A new study suggests that an unconventional method of searching for a certain type of dark matter, called scalar field dark matter, could be relevant. Having no intrinsic spin or direction, these proposed particles are thought to interact weakly with light and matter, rendering them nearly impossible to detect.
What makes this possible is that the gravitational wave detectors are incredibly sensitive (such as LIGO — the Laser Interferometer Gravitational-Wave Observatory). These sensors are so delicate that they can pick up the tiniest warps in spacetime generated by gravitational waves passing through Earth. Using those detectors, the researchers think they can hunt for the hunted signatures of scalar-field dark matter, then perhaps solve one of astronomical science’s great enigmas.
Leveraging Gravitational Wave Detectors
In research that was led by Dr. Alexandre Sébastien Göttel from Cardiff University, the study looks at how scalar field dark matter plays within components within detectors of gravitational waves such as LIGO.
Dark matter may act more like a wave than a particle in some scenarios, Dr. Göttel notes. Gravitational wave detectors could pick up tiny oscillations in normal matter generated by these waves.
A team of researchers further developed their theoretical models to figure out how scalar field dark matter would bind with components essential to LIGO, including the beam splitter and test masses (mirrors). With the influence of dark matter oscillation in such elements, they helped in generating how the output of the gravitational wave detector changes due to scalar field dark matter.
The method is novel and the paper discusses how to take into account the presence of dark matter, which affects distances between test masses in a unique way. Dr. Göttel explains, “On the level of the atoms, one can imagine that on the flap there are always dark matter fluctuations next to electromagnetic field fluctuations.” The effect of oscillations in the dark matter field is essentially changing two fundamental constants, i.e., fine structure constant and electron mass governing electromagnetic interactions.
Using this much finer-grained knowledge of how scalar field dark matter would interact with the LIGO components, the researchers created a robust method to look for remains from the recondite substance in LIGO data.
Conclusion
Although the research team has no definitive evidence of scalar field dark matter in LIGO data, they were able to more robustly constrain how strong the interaction between such dark matter and LIGO components would need be. The bright future for dark matter Direct detection opens up that hope.
