Fermi/LAT observations of 1ES 0229+200: implications for extragalactic
  magnetic fields and background light
  We report the observation in the GeV band of the blazar 1ES 0229+200, which
over recent years has become one 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. (2008) is allowed if the EGMF is strong enough.
On the other hand, an EGMF strength as low as 6x10^-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 on as an exclusion plot in two
dimensional parameter space: EGMF strength vs. EBL density.
