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

¹ Max-Planck-Institut für Radioastronomie (MPIfR), Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: brani@mpifr-bonn.mpg.de
² Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA

Received: 12 August 2014
Accepted: 30 September 2014

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 γ-ray data obtained by the Fermi 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 γ-ray flux variations and the position angle 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 γ-ray flux by 82±32 days. This suggests that the high-energy emission is coming from a region located ≥(3.8±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 γ-ray flares.