Fermi Gamma-ray Space Telescope

Broadband Spectral Energy Distributions and the Classification of Gamma-ray Flaring States in Active Galactic Nuclei

B. Carpenter
R. Ojha, J. Finke, F. D'Ammando, M. Kadler

Abstract:

Blazars are bright, highly variable objects in all wavebands. Gamma-ray flares have been observed in many sources by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. Investigating the source of this gamma-ray emission requires near simultaneous observations at wavelengths from radio to the gamma-ray and in both flaring and quiescent states. The Fermi-LAT all-sky survey mode has made it possible to have gamma-ray data for any point in time during the mission as well as providing alerts on gamma-ray flares on daily timescales so that follow-up observations can be arranged. Gamma-ray flares have shown themselves to have great variety in strength, duration, and the shape of the Spectral Energy Distribution. Radically different flares are seen, sometimes from the same source. This suggests there may be a variety of triggers and/or influences on a flaring state. In order to gain a clearer understanding of the nature of these flares we have attempted to classify the flaring events we have studied as well as some from the literature. We will present a tentative classification scheme and explore how this may be validated and improved.