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B Blazar as the Source of Cosmic Neutrinos Confirmed

  1. Jul 12, 2018 #1


    Staff: Mentor

    Read more at: https://phys.org/news/2018-07-century-old-riddle-resolveda-blazar-source.html

    and a second article from Ars Technica:


    showing how multi-messenger astronomy is revolutionizing science.

    And lastly, this NBC news article:

    Last edited: Jul 12, 2018
  2. jcsd
  3. Jul 13, 2018 #2


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    From that phys.org article...

    The reason they are confident about the source is not just its location, but the timing of a flare up:
    The neutrino was interesting because of the power it packed:
  4. Jul 13, 2018 #3

    Vanadium 50

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    All of these popular articles missed the point. The point is not that one blazar sent one cosmic ray to earth and it was detected. The point is that the same acceleration parameters work for a wide range of cosmic ray detections, and that many/most/all of the high energy cosmic rays come from AGNs.
  5. Jul 13, 2018 #4

    Since the charged particles that comprise cosmic rays would travel a different path through space than neutrinos from the same source, would we ever expect to see both types of particles arrive at earth at the same time from the same direction, or even different directions? If so, why? If not, without that correlation between time of arrival and direction, how do we know the blazar isn’t just a source of high energy neutrinos? How do we know it’s also producing the other components of cosmic rays, which may be produced by some other, as yet undiscovered mechanism?
  6. Jul 13, 2018 #5
  7. Jul 13, 2018 #6
    Sure, charged particles' direction of travel is sufficiently messed up by interstellar / intergalactic magnetic fields to make it impossible to track their origin.

    This observation was of uncharged particles (gamma rays and neutrinos), whose direction of travel can only be altered by a rather strong gravitational field.
  8. Jul 13, 2018 #7
  9. Jul 13, 2018 #8
    So, to slightly rephrase my original question, why "would we ever expect to see both types of particles arrive at earth at the same time from the same direction, or even different directions?"
  10. Jul 17, 2018 #9
    Probably not
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