A search for pair halos around active galactic nuclei through a temporal analysis of Fermi-LAT data

Abstract

We develop a method to search for pair halos around active galactic nuclei (AGN) through a temporal analysis of gamma-ray data. The basis of our method is an analysis of the spatial distributions of photons coming from AGN flares and from AGN quiescent states and a further comparison of these two spatial distributions. This method can also be used for a reconstruction of a point spread function (PSF). We found no evidence for a pair halo component through this method by applying it to the Fermi-LAT data in the energy bands of 4.5-6, 6-10, and >10 GeV and set upper limits on the fraction of photons attributable to a pair halo component. An illustration of how to reconstruct the PSF of Fermi-LAT is given. We demonstrate that the PSF reconstructed by using this method is in good agreement with that which was obtained by using the gamma-ray data taken by LAT in the direction of the Crab pulsar and nebula.

14 pages, 1 figure, a typo corrected. The version published in MNRAS

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• Bow Ties in the Sky I: The Angular Structure of Inverse Compton Gamma-ray Halos in the Fermi Sky
• Bow Ties in the Sky II: Searching for Gamma-ray Halos in the Fermi Sky Using Anisotropy
• Search for gamma rays from SNe with a variable-size sliding-time-window analysis of the Fermi-LAT data
• A geomagnetic filter for the Fermi-LAT background