Gamma Ray Bursters

  1. I've been searching the internet for a reasoanable explanation for the fenomenon and one observation of a GRB 8 billion light years from earth tranformed 1.3 times the mass of the sun into gamma radiation and 16 days later they detected a new blue galaxy with stars already forming. Can someone explain that??
     
  2. jcsd
  3. Phobos

    Phobos 2,020
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    reference link?
     
  4. Chronos

    Chronos 10,053
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    The GRB is a resident of the subsequently observed faint galaxy.
     
  5. _one observation of a GRB 8 billion light years from earth _

    Cor, that's a long way off. Can it harm us or touch us in some way or other?
     
  6. From what I've read about this, a gamma ray burst approx. 6000 light years from earth that points in our direction may annihilate most or all the life on Earth.
    But 8 billion light years away, no, it can't harm us. :)
     
  7. Chronos

    Chronos 10,053
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    Welcome to PF Zig! Indeed, we would not want a GRB to erupt anywhere near planet earth. Even one within 10,000 light years would be pretty scary. But we appear to be in luck. The nearest one to date has been around a billion light years distant. Scintillating to scientists, but not threatening.
     
    Last edited: Jun 25, 2005
  8. Anyway , is the Centauro event real, the one with the proton having a bullets energy hitting the earth. Does this have anything to do with GRBs???
     
  9. Nereid

    Nereid 4,014
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    "the Centauro event"?

    In any case, if a proton had the energy of "a speeding bullet", how would you write that kaos? I mean, you read of particle accelerators making particles with energies of GeV and even TeV ...

    As to a connection between ultra-high energy cosmic rays and GRBs? Stay tuned!
     
  10. Garth

    Garth 3,484
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    GRB's appear to be cosmologically distant, that is GRB after glows are high z. However, because of the significant energy loss by the GZK (Greisen-Zatsepin-Kuzmin 1966) mechanism, the present universe is not transparent to the highest energy cosmic rays (1020 eV), here.

    Therefore any sources contributing to the bulk of these cosmic rays should be within 500 Mpc of earth for 1019 eV CR particles and a few ten's of Mpc for 1020 eV CR particles.

    It would therefore seem to be difficult to sustain a connection between GRB's and the highest energy cosmic rays.

    Garth
     
    Last edited: Jun 27, 2005
  11. Thanks for the warm welcome, Chronos. :)

    I've read about one hypernova only 25 million light years away from here, in the galaxy M74. The GRB didn't hit us though.

    Also, I've heard about some very massive stars in our own galaxy only 5500 light years away that with a 50% or so probability will exterminate most life on Earth within 1 million years when they die.

    If something of this is wrong, please let me know. :)
     
  12. you mean this ? http://en.wikipedia.org/wiki/Oh-My-God_particle :surprised
     
  13. Nereid

    Nereid 4,014
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    That is one possible constraint Garth.

    However, it seems at least some GRBs are close enough to be, potentially, the source of the UHECR, and of course those below the GZK limit could travel much further.

    Looking at GRBs a little more closely, we see that at least some long-soft ones are associated with (at least one kind of) core-collapse supernova, which we also know to occur at all kinds of distances. On top of that, despite the apparent association of one short-hard GRB with a giant elliptical (and so, possibly, a compact object merger scenario), the cause of these is far from settled (even the question of whether there's a single type of progenitor).

    Finally, there's the question of quantity ... does anyone have a good paper they've seen that they'd like to share which compares estimates of likely/possible production rates with what we observe (mediated by flight times and mixmastering by magnetic fields)?
     
    Last edited: Jun 27, 2005
  14. Nereid

    Nereid 4,014
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    Welcome to Physics Forums, OSalcido!

    This CERN article has a few words about Centauro events (yes, they are indeed real, and may help us do particle physics in regimes that will be impossible for us to probe with accelerators we build for ourselves, such as the LHC, for decades or even centuries yet).
     
  15. Chronos

    Chronos 10,053
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    We are not imminently imperiled by any of our stellar neighbors. Eta Carinae, which is about 7500 light years away, is probably the nearest 'immediate' supernova threat. It is an enormous star, so it will put on quite a show. It is not, however, thought to pose any real threat to life on earth. Here is an article that may be of interest:
    http://www.space.com/scienceastronomy/supernova_threat_021216.html
     
  16. Supernovas were more common during the early universe because of faster star formation. Now they are rarer.
     
  17. turbo

    turbo 7,366
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    How do you know this? Is there supportable evidence?
     
  18. It's not that big of a secret... Stars back then formed very fast because the universe had a much larger density.
     
  19. turbo

    turbo 7,366
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    It might not be a secret, but I had not heard that galaxies at high redshift (z~3-6 for instance) have a higher rate of supernovae production than lower-redshift galaxies. Wouldn't we have to see this for the initial statement to be supportable? If you can point me to some supporting evidence, I would be grateful.
     
  20. Near earth GRBs would be harmful only if the beam focus is directed towards Earth...
     
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