Jet outflow and gamma-ray emission correlations in S5 0716+714

TL;DR

This study reveals a significant correlation between gamma-ray flux variations and jet orientation changes in blazar S5 0716+714, indicating a close link between jet morphology and high-energy emission regions.

Contribution

First to report a correlation between gamma-ray flux and jet position angle variations in a blazar, linking inner jet structure with gamma-ray activity.

Findings

Gamma-ray flux variations are correlated with jet position angle changes.

The gamma-ray emission region is located several parsecs upstream of the VLBI core.

Core flux density variations lag gamma-ray flux by approximately 82 days.

Abstract

Using millimeter-very long baseline interferometry (VLBI) observations of the BL Lac object S5 0716+714 from August 2008 to September 2013, we investigate variations in the core flux density and orientation of the sub-parsec scale jet i.e. position angle. The gamma-ray data obtained by the Fermi-LAT (Large Area Telescope) are used to investigate the high-energy flux variations over the same time period. For the first time in any blazar, we report a significant correlation between the gamma-ray flux variations and the position angle (PA) variations in the VLBI jet. The cross-correlation analysis also indicates a positive correlation such that the mm-VLBI core flux density variations are delayed with respect to the gamma-ray flux by 82$\pm$32 days. This suggests that the high-energy emission is coming from a region located $\geq$(3.8$\pm$1.9) parsecs upstream of the mm-VLBI core (closer to the central black hole). These results imply that the observed inner jet morphology has a strong connection with the observed gamma-ray flares.