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Astronomy and Astrophysics 526 (2011) A90
No evidence for gamma-ray halos around active galactic nuclei resulting from intergalactic magnetic fields
A. Neronov1, D.V. Semikoz2, 3, P.G. Tinyakov4, I.I. Tkachev3
(01/02/2011)

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.
1 :  ISDC - INTEGRAL Science Data Center
2 :  APC - UMR 7164 - AstroParticule et Cosmologie
3 :  INR - Institute for Nuclear Research
4 :  ULB - Université Libre de Bruxelles [Bruxelles]
APC - THEORIE
Physique/Astrophysique/Phénomènes cosmiques de haute energie

Planète et Univers/Astrophysique/Phénomènes cosmiques de haute energie
Lien vers le texte intégral : 
http://fr.arXiv.org/abs/1006.0164