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Surprising Gamma Rays From Crab Nebula

  1. Oct 7, 2011 #1

    Dotini

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    Gold Member

    http://www.bbc.co.uk/news/science-environment-15203788
    Astronomers have spotted gamma ray emissions coming from the Crab Pulsar at far higher energies than expected.

    This challenges notions of how these powerful electromagnetic rays - like light, but far more energetic - are formed, researchers suggest in Science.

    They found emissions at more than 100 gigaelectronvolts - 100 billion times more energetic than visible light.


    http://www.sciencemag.org/content/334/6052/69
    Abstract

    We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 giga–electron volts (GeV) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 mega–electron volts and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star.

    Respectfully submitted,
    Steve
     
  2. jcsd
  3. Oct 9, 2011 #2

    Dotini

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    Gold Member

    The findings reveal that current models of pulsars are, at a minimum, incomplete. Speaking to this fact, The Smithsonian Astrophysical Observatory's Martin Schroedte, who performed most of the analytical work for the study, said :

    If you asked theorists a year ago whether we would see gamma-ray pulses this energetic, almost all of them would have said, "No." There's just no theory that can account for what we've found.
    The researchers explore several scenarios that could explain the unprecedented observations in a paper published in today's issue of Science, but ultimately conclude that more observations — possibly requiring next-generation observatory equipment — will be necessary before any new pulsar models can be drawn up.

    For now, astronomers are left to ruminate on the game-changing results of an experiment that many thought should never have been performed.

    "To me it's a real triumph of the experimental approach, not going along with the flow and making assumptions, but just observing to see what there is," said astronomer Rene Ong, spokesperson for the VERITAS gamma ray observatory that was used to detect the Crab Pulsar's radiation.

    "And lo and behold, we see something different than what everybody expected."


    http://io9.com/nepomuk-otte/

    Respectfully submitted,
    Steve
     
  4. Oct 9, 2011 #3

    Drakkith

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    Staff: Mentor

    Wow thats a huge amount of energy...
     
  5. Oct 9, 2011 #4
    250px-Crab_Nebula.jpg

    It may be possible that Type II supernova explosions above 9 solar masses produce baryogenic anti-proton and anti-neutron antimatter residue, as a result of the stellar core shock wave rebounding at near luminous velocity. This could also explain the missing matter and the measured flux, if a matter-antimatter contributing event occurred during the stellar core shock wave rebound.

    Reference:
    http://en.wikipedia.org/wiki/Crab_Nebula" [Broken]
     
    Last edited by a moderator: May 5, 2017
  6. Oct 9, 2011 #5
    I think that we have an example of *OH MY FREAKING WORD-ism* by popular press. The press loves to make things dramatic and breathlessly interesting.



    Which is something that we already new. There is a lot we don't understand about the magnetic fields of pulsars.

    I don't think that's true. Since pulsar magnetospheres are not very well understood, it's very hard to say categorically that something can't happen. Having extremely high energy gamma rays is interesting, but it's not totally unexpected.

    Here is the original paper

    http://arxiv.org/ftp/arxiv/papers/1108/1108.3797.pdf

    This is before you to through the *OH MY FREAKING WORD* filter.
     
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