Tonia M. Venters, Vasiliki Pavlidou
The intergalactic magnetic field (IGMF) may leave an imprint on the
anisotropy properties of the extragalactic gamma-ray background, through its
effect on electromagnetic cascades triggered by interactions between very high
energy photons and the extragalactic background light. A strong IGMF will
deflect secondary particles produced in these cascades and will thus tend to
isotropize lower energy cascade photons, thus inducing a modulation in the
anisotropy energy spectrum of the gamma-ray background. Here we present a
simple, proof-of-concept calculation of the magnitude of this effect and
demonstrate that the two extreme cases (zero IGMF and IGMF strong enough to
completely isotropize cascade photons) would be separable by ten years of Fermi
observations and reasonable model parameters for the gamma-ray background. The
anisotropy energy spectrum of the Fermi gamma-ray background could thus be used
as a probe of the IGMF strength.
View original:
http://arxiv.org/abs/1201.4405
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