Presentation #508.03 in the session “AGN and Quasars 5”.
Flat spectrum radio quasars (FSRQs) are the most luminous blazars at GeV energies, and may be producers of extremely high energy astrophysical neutrinos. However, at TeV energies, only a few such objects have been observed to emit gamma rays, typically during bright GeV flares. We report on the gamma-ray variability and spectral characteristics of three FSRQs that have been observed at TeV energies by VERITAS: 3C 279, PKS 1222+216, and Ton 599. We use a procedure based on Bayesian blocks to identify gamma-ray flares and model the broadband spectral energy distributions of PKS 1222+216 and Ton 599 during TeV detections by VERITAS during flares in 2014 and 2017 to derive constraints on the properties of the gamma-ray emission in these sources. The GeV flux distributions of the three sources are explained well by a physically-motivated stochastic differential equation recently proposed by Tavecchio, Bonnoli, and Galanti (2020), and we interpret the emission in the context of this model.