24–28 Aug 2026
Leiden University
Europe/Zurich timezone

Measuring magnetic fields at cosmological distances with gravitational lensing

Not scheduled
20m
Gorlaeus gebouw (Leiden University)

Gorlaeus gebouw

Leiden University

Einsteinweg 55, 2333 CC Leiden
Talk Primordial Magnetic Fields

Speaker

Willem de Roo (Max Planck Institute for Astrophysics)

Description

Magnetic fields drive galaxy evolution by shaping the interstellar medium and regulating star formation. However, their origins and cosmic history remain obscure. To understand the evolution of magnetic fields from initial seed fields to well-ordered systems, resolving the spatial structure of these fields across cosmic time is essential. Although achievable in local galaxies, this task becomes increasingly difficult at high redshift due to limited angular resolution and faint emission levels.

Strong gravitational lensing provides a unique opportunity to extend our knowledge of magnetic fields to high redshift. Recently, we have developed a new pixellated Bayesian framework that enables us to constrain magnetic fields in both lensing and source galaxies. By combining this technique with high-resolution data from ALMA, we have uncovered a kiloparsec-scale spiral magnetic field in a gravitationally lensed starburst galaxy at redshift 2.6, demonstrating that resolved magnetic field topologies can now be recovered well into the early Universe. In this talk, I will discuss how we apply this approach to probe the topology of magnetic fields in galaxies at cosmological distances, as well as the observational limits and requirements for a systematic survey of magnetic fields across cosmic time.

Author

Willem de Roo (Max Planck Institute for Astrophysics)

Co-authors

Dr Devon Powell (Max Planck Institute for Astrophysics) John McKean (University of Groningen / University of Pretoria) Ruediger Pakmor (Max Planck Institute for Astrophysics) Simon Ndiritu (Max Planck Institute for Astrophysics) Dr Simona Vegetti (Max Planck Institute for Astrophysics)

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