RM Grid - search for magnetic fields on large, cosmological scales

• Applicant: Professor Marcus Brüggen, Ph.D.
• Subject Area: Astrophysics and Astronomy
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564222830

Despite their significance, the origin of magnetic fields on large, cosmological scales remains a mystery. The origin of cosmic magnetic fields has been attributed to primordial processes in the early universe or to astrophysical processes such as outflows from active galactic nuclei or star-forming regions (or a mixture of both). In this proposal, we will constrain cosmological magnetic field via the Faraday rotation of polarised sources with very high precision using low-frequency radio observations with the Low-Frequency Array (LOFAR). Here the focus lies on the so-called RM Grid, which is shorthand for a collection of Rotation Measure values across a particular area of sky that can be used to map magnetic fields in a range of environments. The objectives of this proposal are: (i) Produce and publish a catalogue containing about 10,000 polarised sources (4 x the current number) including extragalactic high-precision RM values at MHz frequencies and (ii) Constrain the properties and origin of the cosmological magnetic fields based on the LOFAR data. For the latter we will employ magneto-hydrodynamical, cosmological simulations that explore various scenarios to produce cosmic magnetic fields.

• DFG Programme: Research Grants