Dark Matter Evidence

[dragon]

For decades scientists have wondered whether a mysterious form of matter – known simply as Dark Matter since it does not interact directly with light – makes up the majority of the “stuff” in the Universe.

Researchers have pointed to the seminal work on the Bullet Cluster of galaxies as evidence that dark matter is a real substance. But similar observations of other galaxy clusters have yielded inconclusive results.

Opponents of the theory suggest that perhaps dark matter is not really matter at all. Instead perhaps our theory of gravity – Einstein’s Theory of General Relativity – is somehow flawed or incomplete. To find the answer, research is ongoing to observe, either directly or indirectly evidence that dark matter actually exists in our Universe.

Now a new study from an international collaboration of scientists has released new, compelling data that suggests that dark matter exists throughout our Universe.

Using an instrument known as the Alpha Magnetic Spectrometer (AMS), the team sorted through over 30 billion cosmic ray events – very high energy particles; mostly protons, electrons and other nuclei – that triggered the detector. They were particularly interested in the ratio of positrons to their antimatter counterpart, the electron.

Certain theories of dark matter predict that the candidate particle is of a special class of self-annihilating matter. Therefore, there is a statistical probability that dark matter collisions could release a significant amount of energy. This energy would eventually manifest itself as electron and positron pairs.

While electrons are common throughout the cosmos, positrons are less prevalent – typically arising from pair production processes. If dark matter is real and theories such as supersymmetry are correct, then dark matter annihilations would cause a rise in the ratio of positions to electrons above 10 billion electron volts (10 GeV).

Using roughly 10% of the data the instrument will accumulate the AMS sees just such a rise up to about 250 GeV. The AMS has sensitivity enough to probe even higher energies, but with fewer events in those regimes, a greater amount of data is needed to have sufficient statistics on the data.

The research also reports an isotropic distribution to the positron flux, meaning that the particles appear to come from all directions equally. This is certainly consistent with the expected dark matter distribution. However, such conclusions are rather soft, as the interstellar magnetic field can bend the path of the particles, masking the direction from which they originated.

Therefore, researchers are not ready to call the matter closed. There is still the possibility that these particles were produced by some other mechanism, perhaps even one that we have not even imagined yet. As additional data is analyzed, the picture will hopefully come into clearer focus. But for now evidence continues to mount for the existence of dark matter.

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[The Xeelee]

Meh, the evidence isn't too compelling currently, but it's a good step.

[madd0ct0r]

spelling in the title though.

[LadyTevar]

Meh, the evidence isn't too compelling currently, but it's a good step.

I rate it about along the lines of "Where there's smoke there's fire", but if they are able to get more data I think they can make a 'hard conclusion' soon.

[The Xeelee]

I am sure we will be there in a couple years and I am pretty sure that this is dark matter detected, but there isn't quite enough evidence to prove it. It's exciting though.

[Baffalo]

I'll be excited when they announce they've proven dark matter exists, or they find the graviton. They know what they're looking for with the graviton, a particle with spin 2, and since they don't have anything else that fits that criteria according to theory, they're pretty certain spotting one will prove the graviton exists. I'm not picky... at this point, just let me experience gravity while standing on the ceiling.

[LadyTevar]

That's the whole problem, isn't it... finding proof of what we think is out there. We've been lucky so far and found that the maths work out, but it's taking literal lifetimes (higgs-boson) for us to have the equipment to find the proof.

[CaiusWickersham]

They were particularly interested in the ratio of positrons to their antimatter counterpart, the electron.

Umm, isn't that the other way around?

[Surlethe]

... no? The electron is the positron's antiparticle.

[Terralthra]

I think he was saying that electrons are typically thought of as matter and positrons as antimatter, rather than positrons as matter and electrons as antimatter.