Dark Matter--it's all around us, accounting for roughly 68% of the universe, yet it's invisible at the same time, presenting an endless set of dilemmas for physicists. Tremendous efforts have gone into constructing machines which prove its existence, while some are aimed at using the presence or absence of the elusive matter to advance theories about space.
Now, astrophysicists are one step closer to understanding the way that dark matter particles are moving within our Solar neighborhood, an area which covers all stars that exist within roughly 15 light years of the sun. And apparently our planet is in their path, which means that Earth will also be battered with what's being described as a "dark matter hurricane".
Mapping Out the Path of the Storm
The S1 stream, the name given to this large collection of moving dark matter, moves in galactic streams at a rate of about 500 km/s. Officially identified in 2017, according to the scientists it originated from a dwarf galaxy "with a total mass comparable to the present-day FORNAax dwarf spheroidal."
To get a better understanding of the density of the stream, they looked at what effects the dark matter would have on weakly interacting massive particles (WIMP) and axions-- both forms of dark matter--existing in our region. From there, they determined enough data on distribution and density to construct a clearer picture of what's happening now, and make future predictions.
As the researchers stated in their paper, "Once the axion mass has been discovered, the distinctive velocity distribution of S1 can easily be extracted from the axion power spectrum."
Increasing Knowledge of Dark Matter Indicators
According to Ciaran O'Hare, Ph.D., in the Department of Theoretical Physics of the University of Zaragoza, and study first author, "[There are] tons of these streams all over the galaxy, some of them are really huge and you can see them in the sky." Since this stream is moving in the path of the sun, it sets up a completely different research scenario for scientists: it will offer the opportunity to learn more about charting dark matter movement.
"Streams are really generic predictions of how we understand galaxies to form," O’Hare explained to Inverse. "Most streams are wispy and small, but a wealth of rich data collected by the European Space Agency’s Gaia satellite on the distance and velocity of over a billion stars gives researchers the details needed to identify streams that are hard to see with the human eye.
Plus, scientists know these dwarf galaxy remains come with dark matter. The really kind of remarkable thing we found about the S1 is that we’re not only sitting inside, but the direction we’re going is the opposite, we’re moving upstream. In testing for it, once we see dark matter, if the S1 stream is there, we can be extra sure the signal we’ve seen is dark matter because we can associate it with this object we can see out in space."
Details about the study appear in a paper, titled "Dark matter hurricane: Measuring the S1 stream with dark matter detectors", which was published November 7th in the Physical Review D journal.