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Evidence of Dark Matter? 130-GeV gamma rays from near our galaxy's core

  1. May 27, 2012 #1
    The Reference Frame: A confirmation of the 130 GeV dark matter-like bump - Lubos Motl
    [1204.2797] A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope - Christoph Weniger
    [1205.1045] Fermi 130 GeV gamma-ray excess and dark matter annihilation in sub-haloes and in the Galactic centre - Elmo Tempel, Andi Hektor, Martti Raidal
    Almost but not quite 5 standard deviations, but if this result holds up, it will be indirect evidence of dark matter.

    Annihilation radiation has already been observed for a more familiar sort of system: The all-sky distribution of 511 keV electron-positron annihilation emission
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  3. May 29, 2012 #2
  4. May 29, 2012 #3
  5. May 30, 2012 #4


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    It will be interesting to see the results of the last run at LHC.
  6. May 30, 2012 #5


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    Interesting. I'm curious, would 130 GeV gamma rays interact in a specific way with the interstellar medium? Would there be a way to detect these gamma rays other than by direct detection by space telescopes?
  7. May 30, 2012 #6


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    144 GeV has been excluded (was just a fluctuation), but there is a strong signal at ~125 GeV, even closer to the 130. However, there is no process which can convert such a Higgs into photons with a peak at 130 GeV. A Higgs mass of 260 GeV would allow that, but that is excluded and I don't see any mechanism which would generate enough Higgs bosons to detect their decay products in astronomy.

    Not different from 100 and 160, I think.

    If their interaction with ordinary matter is strong enough, they might get detected in the LHC. The signature would look different there, depending on the properties of the dark matter particles.
  8. May 30, 2012 #7
    Higgs particles cannot be dark matter, because they are too short-lived for that. A dark-matter particle ought to be able to survive for the age of the Universe, and the purported Higgs particle does not even make it outside the LHC's beam pipes.

    So it's a curious coincidence.

    Back to that 130-GeV particle, I've found some papers in arxiv about what it could possibly be. So from two-photon annihilation alone we can't tell much about it. It likely has various other annihilation modes, but they will likely produce a continuum spectrum and thus may be hard to distinguish.

    If WIMP direct-detection experiments succeed, they will provide additional clues, especially if they discover evidence of a 130-GeV WIMP. Different experiments use different detector materials, so one might be able to disentangle the spin-independent and spin-dependent effects of both protons and neutrons. That means at least 4 experimental numbers, and that will provide more constraints for theoretical models.
  9. May 30, 2012 #8
    I'm not sure that it is a coincidence. 100 GeV is the energy scale for electroweak unification and I'd guess that Higgs mass, dark matter masses, and this energy scale are connected in some weird way.

    It's funny since it looks like every theorist with his pet particle is advancing it as a candidate for the signal. Since there isn't much data yet, not much is excluded.

    Or we could find that it's a statistical fluke or some sort of instrument error. It looks like that we'll at least know if it is "real" in the next 6-8 months.
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