In the latest issue of Nature Astronomy, a research team consisting of scientists from around the world presents its findings concerning dark matter particles. One of them, Dr hab. Szymon Pustelny from the JU Faculty of Physics, Astronomy and Computer Studies, shared some insights about ‘eavesdropping’ on dark matter and why it’s so important.
Despite its many achievements, modern science is still full of questions without answers. One of the most important of them is perhaps the issue of dark matter. Aside from ordinary matter we see all around us that builds stars and planets, the Universe is full of a different kind of matter, one that we cannot detect by normal means, but rather predict its existence. What’s more, based on calculations, it seems that dark matter is four times more plentiful than ordinary matter. And here lies the problem.
All that we know about dark matter, we have learned through indirect measurements. It appears that it is responsible for many phenomena: from the predicted movement of galaxies to bending of light in seemingly empty space to certain fluctuations in the cosmic microwave background, which is what remains from the early Universe. Unfortunately, all attempts to directly investigate dark matter have ended in failure. There could be many reasons for that, and so, several years ago, scientists have proposed creating a network of sensors located far away from one another, hoping that they would be able to detect signals that are impossible to track for any single device.
Cosmic cataclysms, such as supernovas or collisions of black holes, may provide a lot of valuable information about the Universe. For instance, it was a collision of two black holes that finally allowed us to observe gravitational waves for the first time and confirm the predictions of the General Relativity Theory. It’s important to note that such events can not only be a source of gravitational waves, but can also cause ejections of particles into the interstellar medium. Several theoretical models predict that some of these particles might be dark matter, caught in the gravitational field of black holes.
The paper published in the latest issue of Nature Astronomy is an analysis of the probability of detecting such a stream of particles. However, it will only be possible if there are indeed any interactions between dark matter and ordinary matter. Additionally, the search needs to be conducted within a set period of time.
Therefore, the researchers have suggested adopting a multi-messenger astronomy approach. This technique relies on combining the information received from multiple sources (telescopes, radio-telescopes, neutrino detectors, gravitational wave detectors etc.) in order to get the bigger picture. However, there are certain assumptions we need to make if we’re going to use it. Namely, we need to assume that dark matter particles are extremely light (at least a million times lighter than the lightest ordinary particle, the neutrino), which allows them to travel through space with speeds approaching the speed of light.
The paper proposes employing a network of atomic clocks located on GPS satellites and atomic magnetometers in specialist laboratories around the world to detect dark matter. Every one of these sensors could be attuned to a different kind of interaction between ordinary and dark matter. According to the paper, both atomic clocks and magnetometers are accurate enough to detect these particles, making them ideal devices for this difficult but important endeavour.
Original text: www.nauka.uj.edu.pl