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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.
ZOMG, Mom, is that you?
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.
where is the dark antimatter?
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?
Dedicated Cthulhu Cultist since 4523 BC.
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
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.