"Hair" from dark matter around the earth?
Gravity interaction could compress dark matter close to the planetRead out
Dark Halo: Around the Earth and other planets, there could be a whole clump of Dark Matter. Because, as a NASA researcher determined by computer modeling, gravity ensures that the streams of this exotic matter form are compressed into fine hairs that line up around the celestial bodies like a halo. The exciting thing about it: In these hairs, the particles of dark matter are concentrated billions of times - and could therefore be easier to detect.
Dark matter occupies a good quarter of the universe, yet it still gives rise to puzzles. For neither their composition nor their exact distribution are known so far and a direct observation also eludes this exotic matter form. However, because it reveals itself to visible matter through its gravitational effect, we know, among other things, that there is a whole bridge of dark matter in our neighborhood.
Filaments in the solar system
The enigmatic matter form could be even closer to us, as Gary Prézeau of NASA's Jet Propulsion Laboratory in Pasadena said. Using computer simulations, the researcher investigated whether dark matter could be present in our solar system and how it would interact with the Earth and the other planets. The starting point of his models are calculations by astrophysicists, according to which dark matter could form fine currents that occur in the midst of normal matter.
"When gravity interacts with cold dark matter during galaxy formation, all the particles in these streams move at the same speed, " says Prézeau. "There could be many such streams that run through our galactic neighborhood." He compares this to mixing chocolate and vanilla ice cream: when you do that slowly, finer threads of darker and lighter filaments form in the ice.The earth could be surrounded by an entire halo of dark matter filaments. NASA / JPL-Caltech
Halo of fine 'hair' dark matter
Such fine filaments of dark matter may be present in the earth and even pass through our planet, as the astrophysicist explains. Because for dark matter, the earth would not be a real obstacle. However, the models suggest that the gravity of our planet would act like a lens to these filaments, compressing them into fine, concentrated "hairs". display
The earth could therefore be invisible to us - surrounded by a whole halo of such fine hairs of dark matter, reports Pr zeau. According to his simulation, the roots of these "hairs" are located about one million kilometers from the Earth's surface, which is about twice the distance of the Moon. The fine tips of this hair protrude twice as far into space.
Chance to direct proof?
"These 'hairs' are unique windows in the fine structure of the local dark matter streams, " says Pr zeau. And they increase the chance to finally unravel the mysterious nature of this exotic matter form. Because, as the astrophysicist discovered, the particles of dark matter are particularly dense in these "hairs". In the Earth's environment, their density could be a billion times higher than normal good conditions to do it.
"If we could find out the exact location of the roots of these hairs, we could send a space probe and probably get a whole treasure chest of dark matter data, " Pr zeau hopes. How to locate these hairs and what parameters this depends, the researchers has already rudimentary calculated. Accordingly, one would need strong down-cooled detectors, as they already use some space telescopes. However, their sensitivity is still insufficient.
"Dark matter has eluded anyone for 30 years trying to directly prove it, " commented Charles Lawrence, scientific director of astronomy and physics at the JPL. "The roots of these dark matter hairs would be an attractive place to look for them." (Astrophysical Journal, in press; arXiv: 1507.07009)
(NASA / JPL, 24.11.2015 - NPO)