Speaker
Description
Many $\gamma$-ray flares within blazars are highly correlated with flares detected at longer wavelengths; however, a small subset appears to occur in isolation. These orphan $\gamma$-ray flares challenge models of blazar variability. We have developed the 'Ring of Fire' model to explain the origin of these orphan flares. In this model, electrons contained within a blob of plasma moving relativistically along the jet spine inverse-Compton scatter synchrotron photons emanating off of a ring of shocked sheath plasma that enshrouds the jet spine. As the blob propagates through the ring, the scattering of the ring photons by the blob electrons creates an orphan $\gamma$-ray flare. This model has been successfully applied to modeling an orphan $\gamma$-ray flare in the blazar PKS 1510$-$089. To further support the plausibility of this model, we have created a stacked radio map of PKS 1510$-$089 that exhibits a prominent polarimetric signature of a sheath of plasma surrounding the spine of the jet. We have since extended our modeling and stacking techniques to a larger sample of blazars: 3C 273, 4C 71$.$01, 3C 279, 1055$+$018, CTA 102, and 3C 345, most of which exhibit orphan $\gamma$-ray flares.
