The Duty-cycle of Gamma-ray Blazars: a New Approach, New Results

Abstract

We study several properties of blazars detected in the gamma-ray energy range by comparing the EGRET sources with a sample of radio blazars which can be considered possible gamma-ray candidates. We define three classes: non-gamma-ray blazars, blazars with quasi-steady gamma-ray emission, and gamma-ray blazars with substantial activity level. By combining the information of detected and candidate AGNs, we characterise the blazar activity, including the discovery of a region of consistency between the gamma-ray flaring duty-cycle and the recurrence time between flares. We also find a possible relation between the activity index of FSRQs and their black hole mass.

6 pages, 3 figures, to appear in the proceedings of the Gamma 2004 Symposium on High Energy Gamma Ray Astronomy, Heidelberg, July 2004 (AIP Proceedings Series). More detailed results are presented in Vercellone et al., 2004, MNRAS, 353, 890