Sunday, June 19, 2005

Light Milky Cosmic Strings

Have you heard about the excess radiation at the 511 keV line emanating from our galactic center? As announced in New Scientist, two physicists from Ohio argue that the positrons might be produced inside very light superconducting strings, whose tension is near the TeV scale (much lighter than the string conjectured to be relevant for CSL-1 and other recently discussed observations), by electromagnetic induction:

It's a bit confusing if a cosmic string behaves almost just like a regular piece of wire, but their mechanism may be viable under certain assumptions. At least, a new candidate explanation of the strong 511 keV line has been added to the list.

1 comment:

  1. There was already a couple of years ago an article Astronomers claim dark matter breakthrough in New Scientist about this same topic. See also C. Boehm, D. Hooper, J. Silk, M. Casse (2003), MeV Dark Matter: Has It Been Detected?, arXiv:astro-ph/0309686.

    My personal explanation for the MeV gamma rays is based on the explanation of much older anomaly manifesting itself in heavy ion collisions at the collising energy just above the Coulomb wall (my earliest reference seems to be A. T. Goshaw et al(1979), Phys. Rev. Lett. 43, 1065). Evidence for a pion like pseudoscalar resonance decaying to electron positron pair very nearly at rest was found.

    The TGD based identification of the resoance is as a pion like bound state of color octet excitations of ordinary electrons in principle possible in TGD since color is not a spin like quantum number at fundamental level but corresponds to CP_2 partial waves. The decay of leptopion BE condensate induced by the presence of pseudoscalar "instanton density" E.B created in nuclear collisions would yield the strange decay signatures.

    Perhaps the basic reason for why the observed resonances have been put under the rug is that asymptotic freedom dogma excludes them. The decay widths of W and Z simply leave no room for new light particles if asmptotic freedom prevails. If this dogma is given up, it is possible to have an entire hierarchy of physics described by QCD type theories and existing only in finite range of length and momentum transfer scales. This is indeed predicted by TGD if quantum classical correspondence is taken seriously: non-vacuum extremals (with respect to inertial but not gravitational four-momenta) necessarily carry long range classical color fields. Also p-adic fractality forces the same conclusion.


    The second element of the mdoel are TGD counterparts of cosmic strings, which are string like four-surfaces of form X^2×Y^2, X^2 minimal surface in M^4 and Y^2 complex sub-manifold of CP_2 and for all practical purposes look like strings above CP_2 length scale about 10^4 Planck lengths. In TGD cosmic strings dominate the very early cosmology with mass density behaving as 1/a^2 (a is lightcone proper time) so that initial singularity disappears since the mass per comoving volume going to zero. During cosmic expansion they gradually transform to magnetic flux tubes of increasing thickness.

    Long leptohadronic (color) magnetic flux tubes form particular kind of cosmic strings with thickness about 1/m_e are good candidates for the carriers of leptopion BE condensates. The corresponding minimal magnetic field strength of about eB=about m_e^2 =about 10^10 Tesla with cyclotron frequency about electron mass could explain the lines. Magnetic fields of magnitude about 10^9 Tesla have been assigned with supernovae. Note that also cyclotron transitions in a magnetic field with strength about 10^9 Tesla could give rise to photons with energies around MeV but now also the harmonics of the basic line would be observed.

    Leptohadrons would be only a particular case of dark matter whereas dark energy would correspond to the magnetic energy of magnetic flux tubes. A TGD based model for dark matter can be found here. Leptohadrons are discussed here, and leptopions as explanation of .511 MeV gammas are discussed here.


    Matti Pitkanen

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