Talk: Extragalactic B-fields from Gamma Rays

Speaker: Tom Weisgarber (Chicago)

  • Voids: <1nG; filaments: ~0.3 µG; galaxies: ~1 µG; clusters: 10 µG.  No detections of B-fields in voids.
  • Gamma rays interact with the extragalactic background light (EBL) and create electron-positron pairs, which then cascade down to create more gamma rays. This cascade is then observed with some opening angle.  Pair production and inverse Compton scattering are the important processes in creating the cascades.
  • Semi-analytic model for the cascade: Huan+ (2011, ApJL 735, 28). Using the blazar RGB J0710+591, they constrain the B-field to be <3e-16 G (<3e-18 G for a 3 year livetime).

2 thoughts on “Talk: Extragalactic B-fields from Gamma Rays”

  1. In quantam physics thay say one electron can pass through two slits at the same time. I think the electron puts out a field and sends it through the two slits, since they are right next to each other. There was an experiment where an electron make a black spot on a piece of paper. You could try that. See it one electron makes two black spots on the paper.

  2. You can look at each experiment and see if it gives you an idea of something to invent.

    Also, you can start doing things to something and you might think of an invention, one that you didn’t start out to do.

    You can take one characteristic of one invention, and try it on every thing else.

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