Magnetic Universe

Magnetic fields were discovered in our Galaxy and nearby spiral galaxies. Parker (1971) proposed that the dynamo mechanism working in planets also generate magnetic fields in galaxies. Here the conducting layer is the ionized interstellar medium. Differential rotation of spiral galaxies causes the so-called "omega effect". Turbulent motions of helical structure forced by supernovae explosions give the mechanical energy to be transformed to magnetic ones ("alpha effect") in the dynamo process.

We are not sure what is the actual role of magnetic fields in the universe, especially at larger scales: from galaxies through clusters, and maybe even to the whole cosmos, especially in its early days.

Look at introduction pages:

My study of magnetic fields in external galaxies: