No evidence for gamma-ray halos around active galactic nuclei resulting
  from intergalactic magnetic fields
  We analyze the gamma-ray halo around stacked AGNs reported in Ap.J.Lett.,
2010, 722, L39. First, we show that the angular distribution of gamma-rays
around the stacked AGNs is consistent with the angular distribution of the
gamma-rays around the Crab pulsar, which is a point source for Fermi/LAT. This
makes it unlikely that the halo is caused by an electromagnetic cascade of TeV
photons in the intergalactic space. We then compare the angular distribution of
gamma-rays around the stacked AGNs with the point-spread function (PSF) of
Fermi/LAT and confirm the existence of an excess above the PSF. However, we
demonstrate that the magnitude and the angular size of this effect is different
for photons converted in the front and back parts of the Fermi/LAT instrument,
and thus is an instrumental effect.
