Podcaster: Richard Drumm
Title: Space Scoop: Is Dark Matter Kicking Itself?
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1515/
Description: Space scoop, news for children.
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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Transcript:
This is 365 Days of Astronomy. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
Today’s story is…
Is Dark Matter Kicking Itself?
The Universe is full of unanswered questions: Is there life beyond Earth? How did the Universe begin? What is the Universe made of? Well in answer to that last, one of the main ingredients of the Universe is dark matter, perhaps one of the biggest mysteries of all.
Dark matter is a mysterious and peculiar material that got its name because it doesn’t give off any light, not even radio waves – it’s totally invisible. Yet, astronomers think there is 5 times as much of this strange material in the Universe as there is normal matter that we can see, called baryonic matter.
We know that dark matter exists because we can see the effect that it has on the things around it. Like seeing paw prints in the snow made by an invisible dog. And we know that it mostly hangs out around galaxies.
In fact, almost every galaxy with the same shape as the Milky Way (which has a spiral shape, by the way) is surrounded by an envelope of dark matter.
All the clues hinting at the existence and whereabouts of dark matter are caused by its gravity pulling at other objects. At least, it was until now.
For the first time dark matter may have been observed interacting with other dark matter in a way, well, in a way not through the force of gravity.
The picture in today’s album artwork shows a colossal cosmic collision, four giant galaxies in the galaxy cluster Abell 3827 crashing into each other all at once! As astronomers watched this violent event, they noticed that the dark matter cocooning one of the galaxies, was lagging behind its host galaxy. 5,000 light years behind, in fact!
Now this might not sound like much, but it told them that a new force must be at work. Possibly a force that has never been seen before and something that only dark matter can make and be affected by — kind of like the dark matter is kicking itself away!
Computer simulations show that the extra friction from the collision would make the dark matter slow down. The nature of that interaction is unknown; it could be caused by well-known effects or some exotic unknown force. All that can be said at this point is that it is not gravity.
The main uncertainty in the result, is the timespan for the collision: the friction that slowed the dark matter could have been a very weak force acting over a billion years, or a relatively stronger force acting for “only” 100 million years.
Lead author Richard Massey at Durham University in the UK, explains: “We used to think that dark matter just sits around, minding its own business, except for its gravitational pull. But if dark matter were being slowed down during this collision, it could be the first evidence for rich physics in the dark sector — the hidden Universe all around us.”
Hey, Here’s a Cool Fact:
Over 95% of the stuff in our Universe is totally invisible to us. This includes dark matter, but the main ingredient is a mysterious force called dark energy. It pushes everything apart, a bit like the opposite of gravity!
Thank you for listening to 365 Days of Astronomy!
End of podcast:
365 Days of Astronomy
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