How does it look when the Earth is bombarded with dark matter?
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As the Earth travels through space, it constantly collides with dark matter. Although the mysterious particles are unobservable to the human eye, researchers are sure of their existence and believe that they are the "glue" that bind the galaxies of the universe together. Now, scientists have created a computer simulation, called DaMaSCUS, to test what the Earth could look like when it is hit by dark matter and how they scatter across space.
DaMaSCUS has been designed to boost scientists' efforts to detect dark matter particles and allows researchers the opportunity to test out various theories. Scientists have previously theorised that dark matter particles have a very low probability of interacting with atoms within Earth. A number of underground dark matter detectors have been placed under the Earth's surface to pick up such rare dark matter interactions.
However, according to theoretical physicist and associate professor Chris Kouvaris from Centre for Cosmology and Particle Physics Phenomonology (CP3) at the University of Southern Denmark, using standard techniques to detect dark matter may not work when the mysterious particles do not behave as assumed.
If dark matter strongly interacted with Earth's atoms, only to lose energy after travelling through Earth to become undetectable, this would mean exploring an alternative theory on how dark matter particles scatter as they travel across Earth.
Kouvaris and Timon Emken, a PhD student at CP3, use DaMaSCUS to demonstrate how dark matter would scatter as it travels across our planet. The program can simulate billions of dark matter particles that pervades the Earth "and scatter significantly with underground atoms, zig-zagging after every single collision".
Given our planet is moving with respect to the centre of the Milky Way galaxy, dark matter particles primarily hit the Earth from one direction. However, the Earth's rotation in its own axis causes dark matter wind to scatter the particles unevenly within a 24-hour period – this is how daily variation of dark matter signals are created.
Kouvaris suggests that instead of relying on underground dark matter sensors, researchers should use detectors on the Earth's surface when hunting for dark matter signals, looking for daily-varying signals.
Kouvaris and Emken hope to precisely determine the features of these daily-varying signals – such as amplitude and phase – by using DaMaSCUS. If their theory is accurate, this could lead to the actual discovery of dark matter.
The computer program has been made freely available and the research that involved its development has been published in the Journal of Cosmology and Astroparticle Physics (JCAP).
Nasa Hubble image shows the distribution of dark matter in the centre of the giant galaxy cluster Abell 1689, which contains about 1,000 galaxies and trillions of stars