Unlike electromagnetic radiation from astrophysical sources, distant static magnetic fields are inherently difficult to detect. Nonetheless, recent measurements have begun to reveal that such fields exist at significant strengths, and on surprisingly large scales, in the extragalactic universe. These discoveries present us with an important, previously unrecognized component of energy and force in the cosmos.
Magnetic energy is released from individual galaxies. It appears to be captured within zones as large as typical intergalactic separations. Such surprising revelations invite us to understand the role that intergalactic magnetic fields have played in shaping the evolution of galaxies and large-scale groupings of galaxies. These fields doubtless also have an intimate connection with the flux of cosmic rays from outside the Milky Way, whose intergalactic energy density may be comparable to that of the magnetic fields. The acceleration process by which cosmic-ray particles from far away can reach energies as high as 10...
