Where do Cosmic Magnetic Fields come from?

Main list: Physics and Astronomy Colloquia

Abstract

Dr. Anna Scaife
UCL

Magnetic fields are one of the most crucial components of the Universe. Ubiquitous in astrophysics, large-scale fields intersperse the gas in our own Milky Way galaxy, they thread the vast cosmic web that binds together intergalactic matter over cosmological distances, and are present down to the smallest scales, where they are an essential component of star formation processes. The compression and amplification of magnetic fields is a common paradigm in astrophysics wherever matter condenses under gravity, but this process requires a seed field. The question is: where did the seed field come from? Saturation effects imply that this field now remains pristine only in the vast voids in the large-scale structure of the Universe, and it is here that we will be able to distinguish between different models for seed field production. Limits on the strength of the void field have been established by a combination of theoretical and indirect experimental methods, but the magnetic field in voids may also be probed directly. I will discuss these existing limits on the void magnetic field and introduce new limits from the recent observation of cosmic-ray anisotropy by the Pierre Auger Observatory.

  • Venue

    Physics Theatre C

  • Date

    February 23, 2018

  • Time

    From: 10h00 To: 11h00

  • Sponsor

    University of St Andrews
    The oldest university in Scotland, with international renown for both research and education of undergraduates and postgraduates.

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