Fermi/LAT Observations of 1ES 0229+200: Implications for Extragalactic Magnetic Fields and Background Light

I. Vovk (1) , A.M. Taylor (1) , D. Semikoz (2) , A. Neronov (1)

1 ISDC - INTEGRAL Science Data Center
2 APC (UMR_7164) - AstroParticule et Cosmologie

We report the observation in the GeV band of the blazar 1ES 0229+200, which over recent years has become one of the primary sources used to put constraints on the extragalactic background light (EBL) and extragalactic magnetic field (EGMF). We derive constraints on both the EBL and EGMF from the combined Fermi-HESS data set taking into account the direct and cascade components of the source spectrum. We show that the limit on the EBL depends on the EGMF strength and vice versa. In particular, an EBL density twice as high as that derived by Franceschini et al. in 2008 is allowed if the EGMF is strong enough. On the other hand, an EGMF strength as low as 6 × 10-18 G is allowed if the EBL density is at the level of the lower bound from the direct source counts. We present the combined EBL and EGMF limits as an exclusion plot in two-dimensional parameter space: EGMF strength versus EBL density.

Mots clés: BL Lacertae objects: individual: 1ES 0229+200; cosmic background radiation; galaxies: magnetic fields

Domaines: Phénomènes cosmiques de haute energie [astro-ph.HE]; Phénomènes cosmiques de haute energie [astro-ph.HE]; Physique [physics]; Astrophysique [astro-ph]

I. Vovk, A.M. Taylor, D. Semikoz, A. Neronov. Fermi/LAT Observations of 1ES 0229+200: Implications for Extragalactic Magnetic Fields and Background Light. The Astrophysical journal letters, 2012, 747, pp.L14. ⟨10.1088/2041-8205/747/1/L14⟩. ⟨hal-00713443⟩