5.4.2. Background Cosmological Surface ( ~ 8000 Gpc)
Another method to detect an intergalactic magnetic field is based on the delay in arrival of secondary rays with respect to primary rays from QSO and galaxies undergoing outburts. The delay would be caused by the action of an intergalactic magnetic field on the electron cascades caused by the scattering of some rays (photon-photon collisions in the cosmic background radiation, enabling particle pair productions). The time delay is proportional to B2. The question of whether such a proposed model is practical deserves further study. As an example, an intergalactic magnetic field of 10-16 Gauss might have been detected (Plaga, 1995), althought confirmation is needed (see Kronberg, 1995).
Is there a cosmological background screen ? A predicted value of RM = 280 rad/m2 has come out of a recent model of Kosowsky and Loeb (1996), for a magnetic field of 10-9 Gauss, for emission totally generated within the redshift range 900 < z < 1400, near the surface of last scattering for the 2.7° K Cosmic Microwave Background Radiation. Observations of the CMB Radiation at 30 GHz with a 30' beamwidth is proposed. For H0 = 50 km/s/Mpc, q0 = 1, then such a z 1400 corresponds to a distance of about 8 400 Gpc (= 8.4 Teraparsecs).