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Dark Matter Discovered Near Solar System?
gpronger writes "The ATIC (Advanced Thin Ionization Calorimeter) has potentially discovered the presence of dark matter close (only 3000 light-years) to our solar system. The system detected a large-amount of high energy cosmic rays which match the theoretical signature of dark matter annihilating itself. The universe is believed to be composed of about 25% dark matter, but there has been little evidence of it. This discovery, if correct, would be the first."
The paper was published in Nature , but it requires a subscription to see beyond the abstract.
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How amazed would you be to suddenly find that you just forgot what I wrote and you needed to reread my post.... again.
You have a background intensity that is a function of energy, B(E).
Signal intensity is also a function of energy, S(E).
The observed intensity I(E) is B(E) + S(E). The signal portion (observed intensity above background level) peaks at E = 650 GeV. At 800 GeV (and, one would assume, higher), the signal is small enough that the observed intensity is adequately explained only by background.
This must be some meaning of 'close' that I was previously unaware of.
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where is the dark antimatter?
Compared to intergalactic space, 3,000 light years is practically next door. It's all relative, and when it comes to astronomy, anything inside the Milky Way is considered close.
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The universe is believed to be composed of about 25% dark matter, but there has been little evidence of it. This discovery, if correct, would be the first.
If this would be the first evidence how can we already have a little evidence of it?
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The summary misinterprets the results.
The instrument detects high-energy electrons. They found an excess (only 70, but statistically significant) with a particular energy, which if they come from a galactic source (like a pulsar), that source must be within 3000 light years. However, the researchers can't find an appropriate source.
Alternatively, this could be due to annihilating dark matter---the energy spectrum matches some models---but that's not necessarily coming from a particular source.
No, their math is just peachy.
A figure like 650 GeV is the energy of ONE cosmic ray. Think of a graph of the number of rays arriving per second versus the energy of the individual rays. You're getting this many 400 GeV rays per second, this many 500 GeV rays, and so on.
What TFA says is that LOTS of 650 GeV rays were arriving from the newly observed source, and hardly any 800 GeV rays except for the background rate that you get from everywhere in the sky.
rj
Unless and until physicists can fully explain the true mechanism of movement in language that the layperson can understand, I'll remain highly skeptical of their more outlandish conclusions (black holes, wormholes, dark matter, dark energy, big bang, parallel universes, etc.), sorry.
How do you expect the explanations in layman's terms to be any different than what we use now (what goes up must come down, at equilibrium every action has an equal and opposite reaction, object at rest stays at rest until acted upon, etc. etc. etc.)? These are extremely complex phenomena that, if described in layman's terms, cannot be accurately portrayed.
Interestingly enough, the universe is almost certainly much bigger than you believe.
Honestly, we have no idea and probably no real way of determining how big the universe really is. Nonetheless, the observable universe seems to be at least 90 billion light years in diameter. So, it'd be more like finding that random person in the same room.
Space can expand at any rate, including faster than light. The FTL restriction is on matter/energy moving through space. It is not a restriction on the geometry of space itself.
As for where the estimated age comes from, your own link answers that.