Magnetic fields are ubiquitous in our galaxy and influence the detailed study of extragalactic and cosmological signals. The Galactic magnetic field makes it difficult to understand the sources of ultra-high-energy cosmic rays and to study extragalactic magnetic fields. Moreover, coupled to the Galactic magnetic field, matter in the interstellar medium produces polarized emission that prevents us from detecting primordial B modes in the polarization of the cosmic microwave background, and thus from validating the cosmological scenario of primordial inflation. In this talk, I will review some of the observations demonstrating the need to take into account the three-dimensional geometry of the Galactic magnetic field in these research areas. I will then discuss how the polarization of starlight helps in this topic, and present recent developments towards the first tomographic map of the magnetized interstellar medium.
I will discuss these results in the context of ongoing efforts and the promise of future surveys such as Pasiphae.
After his master's thesis on the subject of strong gravitational lensing, Dr. V. Pelgrims obtained his PhD in 2015 at the University of Liège, Belgium, for his research in observational cosmology using quasar polarization as a probe.
As a postdoc in Grenoble, France (2016 - 2018) he began his studies of Galactic polarized emission as a contaminant to the cosmic microwave background polarization and his work on Galactic magnetic field modeling.
Afterwards he embarked on a second postdoc in Heraklion, Greece (2019 - 2023) where he continued this research and also pioneered tomography of the magnetized interstellar medium based on starlight polarization.
He obtained a MSCA fellowship in 2023 and joined the ULB-team. His research focuses on linking the Galactic magnetic field to the measurements of ultra-high-energy cosmic rays performed at the Pierre Auger Observatory.