Probing the jet base of the blazar PKS 1830−211 from the chromatic variability of its lensed images

Abstract

launching mechanism of the jets, PKS 1830-211, gravitational lensing,study images with ALMAduring gamma-ray flare of the source, detect core-shift effect, fittingof spectraprefers a concave over a conical (= free expanding) jet. A concavejet has a flatter spectrum,more shallow drop of the B-field with core-separation, and increasinggamma (=acceleration).So the concave jet represents the jet launching region, the conicaljet the free expanding region.Expect larger core shift in conical jet than in concave jet.co-spatiality of gamma-ray and sub-mm flares !