Multiwavelength variability of flaring gamma-ray blazars: Lessons learned.

Blazars are variable sources on a wide range of timescales at all wavelengths. Their classification (into flat spectrum radio quasars, low-, intermediate- or high-frequency-peaked BL Lac objects; FSRQs, LBL, IBL, HBL) is based on broadband spectral characteristics that do not consider the source being at, possibly, different states of activity.

We review our extensive study of the long-term multi-wavelength variability of a few gamma-ray blazars: The BL Lac object 1ES 1215+303, and FSRQs 3C 279, PKS 1222+216 and Ton 599. One of the main takeaways is that it is important to examine variability across different states of activity. We discuss the cross-correlation and flux distribution  analysis methods we used in order to study the multi-wavelength baseline emission. We describe how our analysis of the flaring states in comparison to quiescent states revealed dramatic transitions of 1ES 1215+303 between blazar subclasses. And finally, to understand the flares themselves, we show how the broadband spectral energy distributions of these sources allowed us to place constraints on the model parameters and on the potential production of PeV-scale neutrino emission during TeV flares.