A research team at MIT, headed by Josu Aurrekoetxea, has introduced a novel way to find dark matter. By examining the ripples from colliding black holes, they have identified a single signal, GW190728, that could be a breakthrough.

Superradiance and the formation of dark matter shells

The theory proposed by MIT postdoctoral physicist Josu Aurrekoetxea suggests that dark matter might be composed of particles far lighter than an electron. Because of this incredibly low mass, these particles act more like coordinated waves than individual grains of matter. When these waves encounter the intense gravitational field of a rapidly spinning black hole, they trigger a phenomenon known as superradiance.

This process allows the black hole to transfer its rotational energy directly into the dark matter waves. As the report describes, this interaction amplifies the density of the particles, effectively "churning" a diffuse cloud into a thick, structured shell of matter. this concentrated shell creates a unique environment that could leave a measurable drag effect on any massive object passing through it.

The anomaly within the 28 signals from LIGO, Virgo, and KAGRA

To test this hypothesis, the MIT team developed a physical model to predict how a merger would look if it occurred inside such a shell. They then applied this model to a dataset containing 28 distinct signals recorded by the global network of gravitational wave observatories , including LIGO, Virgo, and KAGRA.

The analysis revealed a striking discrepancy: while 27 of the signals matched the expected patterns of black holes merging in a vacuum, one signal stood out. The signal catalogued as GW190728 exhibited a pattern that the researchers believe is consistent with the involvement of dark matter. This marks the first time a gravitational wave signal has been identified as a potential dark matter imprint using this specific modeling approach.

Moving beyond the limits of terrestrial particle detectors

For decades, the scientific community has relied on building massive underground detectors to catch a single stray particle of dark matter. However, these efforts have yet to yield a definitive discovery, largely because dark matter does not interact with light, magnetism, or the electromagnetic spectrum. It remains a ghostly presence that passes through planets and even the human body without a trace.

The new approach proposed by the MIT team shifts the focus from Earth-based sensors to the most extreme environments in the cosmos. By observing the gravitational influence of dark matter during black hole mergers, scientists can bypass the need for direct particle interaction. this method leverages the fact that while dark matter is invisible to light, its gravitational pull is undeniable,as seen in the unexpectedly fast rotation rates of spiral galaxies.

The unverified status of the GW190728 candidate

Despite the potential significance of the findings, the researchers are exercising extreme caution. as the report notes, the team is not yet claiming a formal detection of dark matter, but rather a "highly promising candidate signal."

Several questions remain regarding the origin of the GW190728 pattern. It is currently unknown if the signal is a unique signature of dark matter or if it could be explained by other astrophysical phenomena not accounted for in the current model. The scientific community will likely look to the fourth and fifth observing runs of the LIGO and partner observatories to see if similar patterns emerge, which would provide the necessary evidence to move this from a hypothesis to a discovery.