Cosmological investigations of star and galaxy orbits allow for strong conclusions concerning the attractive gravitational forces that act between celestial entities. Scientists have been studying the observable stuff to explain the formation or migration of galaxies. But it is insufficient to explain everything, which implies the existence of a hitherto undiscovered kind of stuff.
In 1933, a Swiss scientist and astronomer named Fritz Zwicky postulated the presence of what is now known as dark matter. Dark matter is a hypothetical kind of matter that is not immediately visible but interacts with the universe via gravity and has about five times the mass of matter we are familiar with.
This illustration shows Earth surrounded by filaments of dark matter called “hairs,” which are proposed in a study in the Astrophysical Journal by Gary Prézeau of NASA's Jet Propulsion Laboratory, Pasadena, California.
Dark Matter and Its Mysteries
According to BBC Science Focus, dark matter is the invisible matter theorized to make up the majority of all matter in the universe. The standard model of cosmology says that dark matter makes up to 85% of all matter in the cosmos, and is 27% of the total mass-energy. It has mass but it is invisible to the eye and does not interact with ordinary matter.
Ivo Schulthess, a Ph.D. student at the AEC and the study's lead author, explained that it is unclear what dark matter is made of. But what is clear is that it is not composed of the same particles as those found in stars, Earth, or even humans.
Over the years, scientists have introduced increasingly sensitive tests and methodologies to seek the presence of the suspected dark matter particles. So far, there have been no results in these efforts.
Certain hypothetical fundamental particles known as axions are a good candidate category for dark matter particles. One significant advantage of these extremely light particles is that they might explain other crucial phenomena in particle physics that are currently unknown.
Now, an international team of researchers succeeded in significantly narrowing the scope for finding dark matter, following the experiment developed at the University of Bern's Albert Einstein Center for Fundamental Physics (AEC).
One Step Closer to Finding Dark Matter
According to SciTech Daily, researchers argue that axions should leave behind a characteristic signature in the measurement apparatus they designed and built if they actually exist.
Professor Florian Piegsa at the AEC said that the experiment allowed them to detect the rotational frequency of neutron spins that move through a superposition of electric and magnetic fields. Each neutron's spin functions in a form of a compass needle, rotating owing to a magnetic field in the same way as the second hand of a timepiece does, but approximately 400,000 times quicker.
He added that they accurately measured the rotational frequency and identified even the tiniest periodic changes by interactions with the actions. It yielded unequivocal results as the rotational frequency stayed steady, which means that there are no axions in the measurement.
The team concluded that they have successfully excluded an important parameter space of dark matter despite the fact that the existence of axions remains mysterious. Future studies could be on the findings and perhaps answer questions about dark matter.
The study, titled "New Limit on Axionlike Dark Matter Using Cold Neutrons" has now been published in the journal Physical Review Letters.
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