The analysis of $gamma$-ray flux variability along with the parsec-scale jet kinematics suggests that the high-energy radiation in the BL Lac object S5 0716+714 has a significant correlation with the mm-VLBI core flux density and with the local orien
tation of the inner jet flow. For the first time in any blazar, we report a significant correlation between the $gamma$-ray flux variations and the variations in the local orientation of the jet outflow (position angle). We find that the $gamma$-ray flux variations lead the 7~mm VLBI core flux variations by 82$pm$32~days, which suggests that the high-energy emission in S5 0716+714 is coming from a region located 3.8$pm$1.9~parsecs closer to the central black hole than the core seen on the mm-VLBI images. The results imply a strong physical and casual connection between $gamma$-ray emission and the inner jet morphology in the source.
We present a high-frequency very long baseline interferometry (VLBI) kinematical study of the BL Lac object S5 0716+714 over the time period of September 2008 to October 2010. The aim of the study is to investigate the relation of the jet kinematics
to the observed broadband flux variability. We find significant non-radial motions in the jet outflow of the source. In the radial direction, the highest measured apparent speed is sim37 c, which is exceptionally high, especially for a BL Lac object. Patterns in the jet flow reveal a roughly stationary feature sim0.15 mas downstream of the core. The long-term fits to the component trajectories reveal acceleration in the sub-mas region of the jet. The measured brightness temperature, T_{B}, follows a continuous trend of decline with distance, T_B propto r_{jet}^{-(2.36pm0.41)}, which suggests a gradient in Doppler factor along the jet axis. Our analysis suggest that a moving disturbance (or a shock wave) from the base of the jet produces the high-energy (optical to gamma-ray) variations upstream of the 7 mm core, and then later causes an outburst in the core. Repetitive optical/gamma-ray flares and the curved trajectories of the associated components suggest that the shock front propagates along a bent trajectory or helical path. Sharper gamma-ray flares could be related to the passage of moving disturbances through the stationary feature. Our analysis suggests that the gamma-ray and radio emission regions have different Doppler factors.
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 a
ngle. 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.
