The Dark Matter From A Long-Gone Galaxy May Be Blowing At 500 Km/s

  • The new study suggests dark matter is blowing like a hurricane in the Milky Way region. 
  • It might leave signals that could be detected in future dark matter searches. 

Scientists were surprised when they first noticed that galaxies do not rotate by the same physics laws as a spinning plate. The stars at the edge of the galaxy rotate faster than previously thought. Why is it so? Is there any mysterious energy that we can’t see?

The answer is yes, and that could be dark matter, which is a hypothetical form of matter, first suggested in 1922. It is estimated to account for nearly 85 percent of the matter in the Universe. However, we haven’t found any solid evidence of dark matter so far.

Scientists worldwide are getting serious on this subject. For decades, they have been observing beyond the standard model of physics to understand more about the nature of dark matter and dark energy.

A new study conducted at King’s College London and University of Zaragoza, Spain, says dark matter is blowing like a hurricane in the Milky Way region. It’s a prediction based on data collected from a set of nearby stars that are drifting away in the same direction.

This so-called S1 stream is thought to be the remnant of a bygone galaxy that was engulfed by our own galaxy billions of years ago. The new study suggests that dark matter from the long-gone galaxy may be moving past us at approximately 500 km/s. If this is the case, the dark matter hurricane might leave signatures that could be detected in future dark matter searches.

Reference: Physical Review D | doi:10.1103/PhysRevD.98.103006

The S1 Stream

The S1 stream was detected in 2017 in the ESA’s Gaia survey to build the richest star catalog with higher precision. This isn’t the first time astronomers all over the world have identified a stellar stream. Over the last couple of decades, they have identified 30 such streams in the Milky Way.

There is one thing common in these streams: they all contain dust particles of a dwarf galaxy that crashed into our galaxy. What’s unique about S1 stream is its trajectory crosses with the Sun.

Dark matter from long-gone galaxyCredit: NASA / Jon Lomberg

In this study, the team measured how S1 affects the dark matter in our region. They took several models into consideration to accurately analyze the distribution and density of the dark matter originated from the S1 parent galaxy.

The team then estimated possible evidence of fast-moving particles in search of dark matter. The advanced instrument searching for one of the most anticipated forms of dark matter — WIMPs (short for weakly interacting massive particles) — may not detect any signals coming out of S1 stream, but the next-generation instrument might.

Read: Is Dark Matter Formed By Cosmic Instability?

Perhaps the next-generation instrument would be axion detectors because if the dark matter hurricane is really out there, its energy spectrum should exhibit a wide bump with a narrow peak.

Written by
Varun Kumar

Varun Kumar is an experienced science and technology journalist interested in machines, AI, and space exploration. He received a Master's degree in computer science from Indraprastha University. To find out what his latest project is, feel free to directly email him at [email protected] 

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