According to new research, the universe could be a lot hairier than one might expect. The “hairs” are filaments of dark matter which form as streams of dark matter pass near massive objects like planets or stars.
The existence of this new phenomenon was proposed by Gary Prézeau of NASA's Jet Propulsion Laboratory in a paper which will be published in the Astrophysical Journal. His simulation shows that the Earth should be surrounded by these filaments, with a bulkier, denser part (the “root”) towards our planet's surface and a thin, less dense part (the “tip”) away from it. The root would be located 1 million kilometers (620,000 miles) from Earth and the tip would extend to over 2 million kilometers (1.2 million miles).
The hairs would essentially be concentrations of dark matter floating in the middle of space, shaped by the influence of the planets and the Sun. Interestingly, if they do exist – which is very much hypothetical at the moment – they could be explored and studied by spacecraft in the future.
"If we could pinpoint the location of the root of these hairs, we could potentially send a probe there and get a bonanza of data about dark matter," Prézeau said in a statement.
Dark matter is a hypothetical kind of matter, accounting for about 85 percent of all the matter in the universe. It doesn’t interact with electromagnetic radiation (i.e. light) so it cannot be seen, hence the appellative “dark”. It interacts only gravitationally, and its existence was proposed to explain how all stars in a galaxy rotate around the center at approximately the same speed.
We are yet to detect dark matter in the lab, but simulations have tried to characterize and constrain its properties. It is thought that dark matter forms low-density regular streams going through galaxies. The low density of dark matter (about 10-22 kg m-3) makes it hard to detect it, but if the “hair” turns out to exist, it would potentially give us an easier chance to observe it: The roots of dark matter hair around our planet are expected to be a billion times denser than the stream, although still more than a trillion time less dense than air.
This simulation shows another potential characteristic dark matter might possess, but as always, further studies are needed to confirm these findings and finally understand dark matter.