Gamma-ray observations of blazars and the intergalactic magnetic field spectrum

C. Caprini (1) , S. Gabici (2)

1 IPHT - Institut de Physique Théorique - UMR CNRS 3681
2 APC (UMR_7164) - AstroParticule et Cosmologie

Very-high energy observations of blazars can be used to constrain the strength of the intergalactic magnetic field. A simplifying assumption which is often made is that of a magnetic field of constant strength composed by randomly oriented and identical cells. In this paper, we demonstrate that a more realistic description of the structure of the intergalactic magnetic field is indeed needed. If such a description is adopted, the observational bounds on the field strength are significantly affected in the limit of short field correlation lengths: in particular, they acquire a dependence on the magnetic field power spectrum. In the case of intergalactic magnetic fields which are generated causally, for which the magnetic field large scale spectral index is $n_B\geq 2$ and even, the observational lower bound becomes more constraining by about a factor 3. If instead $-3

Domains: Physics [physics]

C. Caprini, S. Gabici. Gamma-ray observations of blazars and the intergalactic magnetic field spectrum. Physical Review D, 2015, 91 (12), ⟨10.1103/PhysRevD.91.123514⟩. ⟨cea-01220566⟩