CTA 102 -- year over year receiving you

TL;DR

This paper analyzes the prolonged high-activity state of the FSRQ CTA 102, attributing the peak gamma-ray and optical fluxes to gas cloud ablation by the jet, and contextualizes this within a two-year high-state period.

Contribution

It introduces the cloud-ablation scenario as an explanation for CTA 102's extended high-activity state and provides a detailed interpretation of the observed lightcurve.

Findings

Peak activity linked to gas cloud ablation by the jet

Two-year high-state characterized by increased flux and variability

Contextualization of the activity within a broader high-state period

Abstract

The FSRQ CTA 102 (z=1.032) has been tremendously active over the last few years. During its peak activity lasting several months in late 2016 and early 2017, the gamma-ray and optical fluxes rose by up to a factor 100 above the quiescence level. We have interpreted the peak activity as the ablation of a gas cloud by the relativistic jet, which can nicely account for the months-long lightcurve in 2016 and 2017. The peak activity was in the middle of a 2-year-long high-state, which was characterized by increased fluxes and increased rms variability compared to the previous low-states, and which was flanked by two bright flares. In this presentation, we put the cloud-ablation scenario into the broader context of the 2-year-long high-state.