Challenges in reconciling observations and theory of the brightest high-energy flare ever of 3C 279

Recent high-energy missions have allowed keeping watch over blazars in flaring states, which provide deep insights into the engine powered by supermassive black holes. However, having a quasar caught in a very bright flaring state is not easy requiring long surveys. Therefore, the observation of such flaring events represents a goldmine for theoretical studies. Such a flaring event was captured by the INTEGRAL mission in June 2015 while performing its (as of today) deepest extragalactic survey when it caught the prominent blazar 3C 279 in its brightest flare ever recorded at gamma-ray energies. The flare was simultaneously recorded by the Fermi gamma-ray mission, by the Swift mission, by the INTEGRAL mission and by observations ranging from UV, through optical to the near-IR bands. The derived snapshot of this broad spectral energy distribution of the flare has been modeled in the context of a one-zone radiation transfer leptonic and lepto-hadronic models constraining the single emission components. The derived parameters of both models challenge the physical conditions in the jet. However, very recently published very-high-energy (VHE) data at TeV energies are very close to our lepto-hadronic model.