Probing the cosmic magnetism with gamma-ray observations of extragalactic sources
Paolo Da Vela (INAF - OAS)
Tuesday 25/02/2025 @ 14:00, Sala Antonio Sollima (IV piano Battiferro)
The origin of magnetic fields on cosmological scales remains one of the longstanding problems in cosmology. Magnetic fields with strengths on the order of 1–10 microG are typically measured in galaxies through observations of Faraday rotation and Zeeman splitting of atomic lines in the radio band. It is widely accepted that these fields originate from weak seed fields that are amplified through mechanisms such as the alpha-omega dynamo. However, the nature of these weak seed fields remains largely unknown. To constrain different formation scenarios, it is crucial to search for signatures of magnetization in cosmic voids, which are regions devoid of large-scale structures. In this talk, I will present an innovative technique based on gamma-ray observations of extragalactic sources that enables the probing of the weakest magnetic fields in the voids between galaxies. I will also review the most recent results obtained using blazars and gamma-ray bursts (GRBs).