2004•MSAISRequires access
Duty-cycle and gamma -ray activity of EGRET blazars
S. Vercellone, S. Soldi, A. W. Chen, M. Tavani
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Abstract
Active Galactic Nuclei (AGNs) show high variability in the γ-ray energy band above 30 MeV on time-scales, in some cases, as short as one day. Up to now, the sparse coverage provided by the EGRET instrument has made it difficult to firmly establish both if and especially how often the transient activity occurs. We report our results on the estimate of the duty–cycle of γ-ray blazars by means of a re-analysis of the EGRET data and their comparison with numerical simulations. We attribute a γ-ray activity index, ψ, to all EGRET blazars, and show that FSRQs dominate the sample with non-zero ψ. We also characterise the blazar activity, including the discovery of a region of consistency between the γ-ray flaring duty–cycle and the recurrence time between flares.