Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Origin of Cosmic Rays and GRB (new paper by A.Dar)

  1. Aug 17, 2004 #1

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    http://arxiv.org/astro-ph/0408310





    The Origin of Cosmic Rays - A 96-Year-Old Puzzle Solved?
    Arnon Dar
    Invited talks to be published in the proceedings of the 2004 La Thuile Workshop on Perspectives In High energy Physics, La Thuile, Aosta Valley, Italy, February 29-March 6, 2004 and of the 2004 Vulcano Workshop on Frontier Objects in Particle Physics and Astro Physics, Vulcano, Italy, May 24-29, 2004

    ----quote from Abstract-----
    There is mounting evidence that long duration gamma ray bursts (GRBs) are produced by ultra-relativistic jets of ordinary matter which are ejected in core collapse supernova (SN) explosions. Such jets are extremely efficient cosmic ray (CR) accelerators which can accelerate the swept up ambient particles on their way to the highest observed CR energies. The bulk of the jet kinetic energy is used to accelerate CRs while only a tiny fraction is used to produce the GRB and its afterglow. Here we use the remarkably successful cannonball (CB) model of GRBs to show that the bipolar jets from SN explosions, which produce GRBs most of which are not beamed towards Earth, can be the main origin of cosmic rays at all energies. The model explains very simply the elemental composition of CRs and their observed spectra at all energies. In particular it explains the origin of the CR knees and ankle. Above the CR ankle, the Galactic magnetic fields can no longer delay the free escape of ultra-high energies CRs (UHECR) from the Galaxy, and the CRs from the intergalactic medium (IGM), which were injected there by SN jets from all the galaxies and isotropized there by the IGM magnetic fields, dominate the Galactic CR spectrum. A Greisen-Zatsepin-Kuzmin (GZK) effect due to the interaction of UHECRs with the microwave background radiation is expected. The CR nuclei which diffuse out of galaxies, or are directly deposited in the IGM by the relativistic SN jets, may be the origin of the IGM magnetic fields. Inverse Compton scattering of the cosmic microwave background radiation (MBR) by the CR electrons in the IGM produces the diffuse extragalactic gamma-ray background radiation (GBR).
    -----end quote----
     
  2. jcsd
  3. Aug 19, 2004 #2

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    Gammaray Bursts as Standard Candles

    http://arxiv.org/abs/astro-ph/0408350

    a new kind of standard candle to measure the universe with

    in the 1990s they studied Type IA supernova, using them as standard candles, and in 1998 they came up with the accelerating expansion

    Hubble was using Cepheids as standard candles in the 1930s and he came up with the expansion

    sometimes a new standard candle brings along a new finding

    these people are talking as if GRB could be a standard candle,
    dont know if its reasonable or not
     
  4. Aug 20, 2004 #3

    Chronos

    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    I think it is very unreasonable [which probably means it is correct]. Perhaps I have not studied GRB to the necessary extent. I would be very curious as to the red shift. I still think long duration GRB's are hypernova phenomenon. It is the short ones that intrigue me. Hypernova make a great deal of sense. The early universe was surely populated by insanely massive stars.
     
  5. Aug 21, 2004 #4
    As I was intrigued by the cannonball model, I found this interesting explanation
    http://www.space.com/scienceastronomy/aas202_gamma_030528.html
    "Data from the National Science Foundation's Very Long Baseline Array and other telescopes show that matter streamed from the collapsing star at about 98 percent of the speed of light in a smooth, rather orderly manner many days after the initial eruption, explained Dale Frail of the National Radio Astronomy Observatory.

    This supports the leading model for GRBs, known as the fireball model, which supposes a continuous stream of matter and energy racing outward. It refutes another theory, known as the cannonball model, which held that Earth-mass blobs of material were shot out."
     
  6. Aug 21, 2004 #5

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    meteor I read the link (you have been posting some especially interesting ones)
    It throws considerable doubt on the cannonball model (which Arnon Dar was using) in favor of the fireball model.

    If possible I would like this thread to be more balanced, by someone posting an alternative explanation of how GRB and CR are caused in the fireball picture. (or even just how GRB is caused, forget about cosmic rays)

    It is pretty new and exotic to me personally. If you find more good papers please post them!
     
  7. Aug 22, 2004 #6
    Hi
    This is the paper where the cannonball modle was proposed for the first time
    http://arxiv.org/abs/astro-ph/0008474
    A cannonball model of gamma-ray bursts: superluminal signatures

    Authors: Arnon Dar, Alvaro De Rujula
    Comments: 9 pages, 5 figs, latex2e
    Report-no: CERN-TH/2000-257

    "Recent observations suggest that the long-duration gamma ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in supernova explosions. We propose that the result of the event is not just a compact object plus the ejecta: within a day, a fraction of the parent star falls back to produce a thick accretion disk. The subsequent accretion generates jets and constitutes the GRB ``engine'', as in the observed ejection of relativistic ``cannonballs'' of plasma by microquasars and active galactic nuclei. The GRB is produced as the jetted cannonballs exit the supernova shell reheated by the collision, re-emitting their own radiation and boosting the light of the shell. They decelerate by sweeping up interstellar matter, which is accelerated to cosmic-ray energies and emits synchrotron radiation: the afterglow. We emphasize here a smoking-gun signature of this model of GRBs: the superluminal motion of the afterglow, that can be searched for ---the sooner the better--- in the particular case of GRB 980425."

    I can't decide if I prefer the fireball model or the cannonball model. I should read the paper first
     
  8. Aug 23, 2004 #7

    Nereid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    It either is not, or quite premature. At least two well observed GRBs have been 'underluminous'. Even the long-duration GRBs aren't yet well modelled by hypernovae, or any other kind of supernova - despite some of the hype; it's true that there's certainly an interesting set of consistent data for *some* long-duration GRBs.

    This recent ESA PR may be some interest.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Origin of Cosmic Rays and GRB (new paper by A.Dar)
  1. Supernovae GRB paper (Replies: 25)

  2. Cosmic Rays (Replies: 1)

  3. Cosmic rays (Replies: 2)

Loading...