High-resolution polarization imaging of the Fermi blazar 3C 279

TL;DR

This study combines high-frequency VLBI polarization imaging and Fermi-LAT gamma-ray data to investigate the magnetic field topology and emission regions in blazar 3C 279, revealing multiple gamma-ray emission sites and their relation to jet morphology.

Contribution

It provides new insights into the location of high-energy emission regions in blazar 3C 279 using combined radio and gamma-ray observations, highlighting multiple emission sites.

Findings

Multiple gamma-ray emission regions identified.

Ejection of new jet components correlates with gamma-ray flares.

High-energy emission occurs upstream of the 43 GHz core.

Abstract

Ever since the discovery by the Fermi mission that active galactic nuclei (AGN) produce copious amounts of high-energy emission, its origin has remained elusive. Using high-frequency radio interferometry (VLBI) polarization imaging, we could probe the magnetic field topology of the compact high-energy emission regions in blazars. A case study for the blazar 3C 279 reveals the presence of multiple gamma-ray emission regions. Pass 8 Fermi-Large Area Telescope (LAT) data are used to investigate the flux variations in the GeV regime; six gamma-ray flares were observed in the source during November 2013 to August 2014. We use the 43 GHz VLBI data to study the morphological changes in the jet. Ejection of a new component (NC2) during the first three gamma-ray flares suggests the VLBI core as the possible site of the high-energy emission. A delay between the last three flares and the ejection of a new component (NC3) indicates that high-energy emission in this case is located upstream of the 43 GHz core (closer to the black hole).