From Seed Fields to Magnetism in Planets and Galaxies

This study explores the origin and evolution of magnetic fields in planetary bodies and galaxies, focusing on the role of an initial seed magnetic field (SMF) required for dynamo operation. We propose a general physical mechanism in which a seed field arises naturally in systems where an orbiting body rotates non-synchronously relative to its central mass. Building on this idea, we derive a unified formulation for the SMF that is applicable across both planetary and galactic scales and incorporates fundamental parameters such as orbital distance, rotational velocity, and core radius. To relate the seed field to observed magnetic field strengths, we introduce a dimensionless parameter that represents the efficiency of dynamo amplification. Model predictions are compared with magnetic field measurements from the solar system and the Milky Way. The results suggest that observed magnetic fields can be interpreted as the product of a universal, gravity-induced seed field and a system-dependent amplification factor. This framework offers a complementary perspective on magnetic field generation in a wide range of astrophysical environments and highlights potential implications for magnetism in extreme settings, including regions surrounding black holes.