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AGN, GRB and danger for Earth

  1. Dec 18, 2009 #1
    I've got a small homework question that goes:

    Which would be more dangerous and why: Eta Carina exploding as a gamma-ray burst, or
    the black hole at the Galactic centre accreting material at the same rate as a typical luminous
    Seyfert galaxy?

    I have simply estimated the flux from both of them given the average energy output of GRBs and AGNs, and their distance from the Su with inverse square law. Does it make sense that the GRB, closer and slightly more energetic is way more dangerous for life on Earth?
  2. jcsd
  3. Dec 18, 2009 #2


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    The danger posed to earth would be based on the radiation levels reaching earth.

    Calculating the flux as a function of source strength and distance is the way to go.

    Edit: Please refer to cross reference: WR104 Gamma Ray Burst
    Last edited: Dec 27, 2009
  4. Dec 18, 2009 #3


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    I don't think you can use the inverse-square law for a gamma-ray burst. Think about it for a moment and see if you agree.
  5. Dec 18, 2009 #4
    Are you hinting something regarding the presence of relativistic jets? Doesn't the inverse square law work anyways, both for a spherical radiation and for a beamed one?
  6. Dec 19, 2009 #5


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    Not entirely, a beamed jet could be a danger. They appear to be collimated not unlike a laser beam due to intense magnetic fields of the star. It does not, however, appear Eta Carinae is much of a threat. Its rotational axis is not aligned with earth and is unlikely to become a gamma burster, more likely a garden variety stellar collapse supernova. The SMBH is an even more remote threat. It has no significant 'food' source at present and that is unlikely to change for millions, if not billions of years.
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