VERA frequent monitoring of the parsec-scale jet in the BL Lac object OJ 287 simultaneous with gamma-ray flares during 2011-2012

We present a kinematic study of the parsec-scale radio jet in the most studied BL Lac object OJ 287, during γ-ray flares to explore the relation between parsec-scale radio jet activity and γ-ray emission. VLBI observations were carried out toward OJ 287 from 2010 November to 2012 September at 22 GHz using the VLBI Exploration of Radio Astrometry (VERA). The 22-GHz light curve of OJ 287 show three obvious flare events around 2011 May, 2011 October, and 2012 March. The second radio flare occurred during the γ-ray flaring period, and the third radio flare seems to precede the γ-ray flare by one month. One jet component moved outward with respect to the core component with an apparent superluminal speed (∼ 11c) from 2010 November to 2011 November. Then it changed direction, moving apparent inward in 2011 November, when the γ-ray flare occurred. The observed apparent inward motion of the jet at 22 GHz could be caused by the new jet component unresolved at 22 GHz in the innermost region.