|Speaker:||Francesco Miniati (ETH)|
|Title:||Generation of Magnetic Field in Cosmic Structure|
|Date:||Thu, Nov 24, 2011, 16:00 - 17:30|
|Place:||Seminar Room A|
Magnetic fields are a common feature of cosmic bodies, including planets, stars and young galaxies and even the largest structures of the universe. Recent experiments based on gamma-ray observations of distant blazars suggest that even void of galaxies are permeated with magnetic fields, with strengths >= 10^-18 G or so, which are extremely difficult to explain with astrophysical processes.
After a brief review of observations, I will focus on a "resistive" mechanism for the generation of intergalactic magnetic fields before the end of re-ionization. In this model, magnetic field is generated by the streaming of cosmic-ray particles produced by the same galaxies and stars that are also responsible for the re-ionization of the universe. I will describe the model and present numerical simulations of structure formation that include self-consistently the resistive source of magnetic field, and show that magnetic seeds are produced throughout cosmic space, consistent with measurements in voids from gamma-ray experiments.