M. S. Pshirkov, G. I. Rubtsov
We search for the long-term variability of the \gamma-ray sky in the energy
range E > 1 GeV with 168 weeks of Fermi-LAT data. We perform a full sky blind
search for regions with variable flux looking for deviations from uniformity.
We bin the sky into 12288 bins using Healpix package and use Kolmogorov-Smirnov
test to compare weekly photon counts in each bin with a constant flux
hypothesis. The weekly exposure of Fermi-LAT for each bin is calculated with
the Fermi-LAT tools. We consider flux variations in the bin significant if
statistical probability of uniformity is less than 4e-6, which corresponds to
0.05 false detections in the whole set. We identified 117 variable sources,
variability of 27 of which has not been reported before. Among the sources with
previously unidentified variability there are 25 AGNs belonging to blazar class
(11 BL Lacs and 14 FSRQs), one AGN of uncertain type and one pulsar PSR
J0633+1746 (Geminga). The observed long term flux variability of Geminga has a
statistical significance of 5.1\sigma.
View original:
http://arxiv.org/abs/1201.3625
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