Space

Dark matter 'can't touch this' or even itself, researchers find

Galaxy cluster MACS J0416.1–2403 with dark matter map (Image: NASA/ESA)
Galaxy cluster MACS J0416.1–2403 with dark matter map (Image: NASA/ESA)
View 5 Images
The Hubble space telescope in orbit (Image: NASA/ESA)
1/5
The Hubble space telescope in orbit (Image: NASA/ESA)
A collage of galaxy clusters with dark matter maps in blue and x-ray visible gases in pink (Image: NASA/ESA)
2/5
A collage of galaxy clusters with dark matter maps in blue and x-ray visible gases in pink (Image: NASA/ESA)
Galaxy cluster ZwCl 1358+62 with dark matter map (Image: NASA/ESA)
3/5
Galaxy cluster ZwCl 1358+62 with dark matter map (Image: NASA/ESA)
A collage of galaxy clusters with dark matter maps (Image: NASA/ESA)
4/5
A collage of galaxy clusters with dark matter maps (Image: NASA/ESA)
Galaxy cluster MACS J0416.1–2403 with dark matter map (Image: NASA/ESA)
5/5
Galaxy cluster MACS J0416.1–2403 with dark matter map (Image: NASA/ESA)

When we look out into the universe, we don't know what we're looking at for the most part. In fact, we can't even see most of what we're looking at – that's because the majority of the universe is made up of mysterious, practically invisible dark matter. But new observations from the Hubble Space Telescope and NASA's Chandra X-Ray Observatory have unraveled the mystery little bit, with the new revelations hinting that dark matter could actually be even darker than previously thought.

Dark matter is just what it sounds like: matter that does not emit, reflect or absorb light, so it is invisible. However, we know it is there because of its measurable gravitational effects on parts of the universe that we can see. As such, one of the best ways to study dark matter is to observe what happens when galaxies containing large amounts of the stuff collide with each other.

"We know how gas and stars react to these cosmic crashes and where they emerge from the wreckage. Comparing how dark matter behaves can help us to narrow down what it actually is," said David Harvey of the Swiss École Polytechnique Fédérale de Lausanne (EPFL), lead author of a new study that looked at 72 galactic collisions using Hubble and Chandra data.

During these violent events, the stars of the colliding galaxies do not slow down because they are actually far enough away from other stars to travel through the crash without their progress being impeded. The researchers found that dark matter also does not slow down as galaxies collide, but this is not because it is far away from other dark matter as with stars – dark matter is believed to be spread evenly through galaxy clusters, meaning that the particles would often get very close to each other.

The resulting conclusion is that in addition to not interacting with visible matter, dark matter also does not interact with other dark matter.

A collage of galaxy clusters with dark matter maps in blue and x-ray visible gases in pink (Image: NASA/ESA)
A collage of galaxy clusters with dark matter maps in blue and x-ray visible gases in pink (Image: NASA/ESA)

"A previous study had seen similar behavior in the Bullet Cluster," says team member Richard Massey of Durham University. "But it's difficult to interpret what you're seeing if you have just one example. Each collision takes hundreds of millions of years, so in a human lifetime we only get to see one freeze-frame from a single camera angle. Now that we have studied so many more collisions, we can start to piece together the full movie and better understand what is going on."

The latest results would seem to rule out the possibility that interactions with dark matter can create a strong frictional force. Next, the team plans to study whether or not a different type of interaction might make dark matter particles bounce off each other or cause dark matter blobs to change their shape.

One theory posits that dark matter might be made up of so-called "supersymmetric" particles – a new, unconfirmed and more massive particle that interacts only weakly with electrons, protons, neutrons and the other known particles of the Standard Model.

The research paper, entitled "The non-gravitational interactions of dark matter in colliding galaxy clusters," is in the latest installment of the journal Science.

Source: ESA

9 comments
Alan Gervasi
If the Universe is an expansion of gravity with time embedded like electrical impedances, then space including embedded matter is pulled through time like a lure in water fluttering along in time. Then Dark Matter would likely not be visible to light because light skips over it. Collisions in colliding galaxies would still be visible but far less than one would expect, because the only collisions accountable would be the ones occurring in precisely during our "time."
DarkLight
Light 101: In a cave, dark as space, a candle glows. We see candle light 'shining' at us, we see reflected candle light off the cave's walls. We see our sun's light 'shining' right at us, we see our sun's light reflected off our solar system's planets and moons. We don't see 'that' light before it's reflected, but because it's reflected we know it's there. Light's defined as a wave, a particle, or both. Wave or particle, both denote substance. Substance has mass. When that mass is 'shining' at us it's called light, when that mass is shining away from us it's called 'Dark Matter.' .
Brian Tray
Dark matter.......another concept developed by "mathemagicians" that can't be experimentally confirmed or observed. When will the "established" cosmologists just throw in the towel and face the facts? Gravity is too weak to be the driving force for galaxy formation. The concepts of black holes, neutron stars, and dark matter/energy all require the known laws of physics and chemistry to break down. Yet none of these concepts has ever been observed and they defy confirmation. All they require is that one "believes" the story. This sounds much like a religion and very little like science. Math should be used to confirm observable reality, not create it. However, it seems the end of the "standard model" is close at hand (thank goodness). The newest data coming in from satellite based radio telescopes is proving to be one contradiction after another for the standard model of cosmology. Even the coupling of red shift with distance/velocity appears to be incorrect. Chandra has revealed a galaxy and a quasar in physical contact with each other. They have dramatically different red shifts. Apparently red shift is a function of age, as proposed by Halton Arp in his work "Seeing Red". This will invalidate the big bang theory as well as inflation. The MMS mission is confirming the findings of Voyager and IBEX. The standard stellar model (nuclear fusion at the core) is in big trouble. The lack of convection velocities in the sun is a problem that cannot be overcome. With the discovery of massive magnetic fields and electric currents between stars and galaxies ("rivers of hydgrogen") it seems that the electric universe cosmologists may have been correct after all. It is about time that astrophysics and cosmology returns to the folds of science and leaves the realm of science fiction.
Erik Best
Brian Tray, I think its great that your skeptical of dark matter; I am too. However, I think your criticisms are a little harsh. Dark matter is a theory put forth to explain very real observed phenomenon that presents itself as if there were this 'invisible' mass we have yet to be able to detect by any means other than it's gravitational exertion. It's a fairly natural theory to propose I think given what we know and can observe. It could turn turn out to be absolutely wrong, much like the proposed ether before we concluded that theory was just wrong. Regarding, "The concepts of black holes, neutron stars, and dark matter/energy all require the known laws of physics and chemistry to break down. Yet none of these concepts has ever been observed and they defy confirmation". I think the vast majority of astrophysicists would disagree with that. We can actually observe neutron stars and black holes. The scientific community is very comfortable accepting these objects as matter of facts. But I suppose you see some flaw in all their logic? I guess you're a genius of such proportion that even other experts in the field cannot recognize it, like an undiscovered Einstein of sorts? You'll forgive us if we are skeptical of your amazing grasp of the true nature of the universe. Perhaps you should explain your thoughts in more precise and rigorous detail, like Mathemagicians do and collect your Nobel Prize? http://neutrinodreaming.blogspot.com/2011/09/electric-universe-theory-debunked.html
David Brown
re. 'light 101' -- Assuming for the moment, that dark matter is intrinsically linked in some fashion to gravity or a gravity effect, how can one deduce that a receding photon might produce a gravitational distortion? If you have a rationale I would like to hear about it ...... No? well, let me take a stab at it and fail miserably. Given that E =Mc2, let's just forget [for the moment] the speed of light squared [c2] and go with E=M and M=E. What the new observational data may indicate is that dark matter - and I am way out on a limb here so please, no laughing or I'll lose my grip - could possibly, remotely [did I already say possibly, be a hybrid of the of Alberts equation. In other words, neither energy nor matter but some conjunction of both in a steady state. And further on that limb so as to get my ass kicked by my physics prof, would the concept of wave propagation, similar to the electromagnetic effect of that name, play a role in the creation of space-time as we currently understand it? Perhaps our reality is that we really are just living in the 'wake' of receding photons and dark matter is just the effect of turbulence in space/time. I now have given myself a headache So to sum up, jus' sayin'.
John Pettitt
+1 Brian Tray
DarkLight
Our current understanding about almost everything is infantile [understand almost is actually a big chunk when linked with everything]. I'm simply stating photons have mass. It would be difficult to measure any gravitational distortion a single photon produces, but in mass (immediately around a star) there it is. Now you can dazzle with your physics' "theories," but if photons don't have mass then they only exist as a wave. Photons fill the universal 'void' like a fluid.
Bob
IF the Big Bang was true, I think it happened more like 50+ billion years ago. (Using the current 13.7 billion years requires the imaginary inflation theory to explain.) The development of the heavy elements requires there to be several generations of stars which went nova and later reformed concentrating the heavier elements. If about 20% of each generation of stars was too small to go nova, they would become cold invisible cinders in space. After about seven generations of stars, this 20% conversion to cold cinders and only 80% new stars, means that the greatest bulk of the mass of the universe is now cold invisible NORMAL matter and not some imaginary dark matter. The gravitational effects of all this cold mass and its distribution likely explains any observations being declared imaginary dark energy. Another fly in the ointment is gravitational lensing and refractive index which can distort what we see. I also have a feeling that much of what we see has also been affected by light pressure and electrical charges over the years. Any data extrapilated back billions of years quickly becomes nearly meaningless without knowing what could have affected its path and what clouds of gas or galaxies it passed through on its way to the present. Trying to use this distorted data as proof is just delusion. Too many mathematicians have the mistaken idea that somehow good math purifies bad data.
Douglas Bennett Rogers
Enough variables, such as cosmic microwave background temperature, match up to make dark matter highly probable. The other suggestions have some very serious problems.