Transverse Oscillations of the M87 Jet Revealed by KaVA Observations

Recent VLBI monitoring has found transverse motions of the M87 jet. However, due to limited cadence previous observations, details motion have not been fully revealed yet. We regularly monitored jet at KVN and VERA Array (KaVA) 22 GHz from December 2013 June 2016. The average time interval observation is ∼0.1 year, which suitable for tracking short-term structural changes. From these well represented by double ridge lines in region 2–12 mas core. that exhibit oscillations all observed regions with an period 0.94±0.12 years. When sinusoidal fit performed, we amplitude this oscillation order mas, northern southern limbs are almost phase. Considering amplitude, it does originate Earth’s parallax. propose possible scenarios oscillation, such as propagation instabilities or magneto-hydrodynamic (MHD) waves perturbed mass injection around magnetically dominated accretion flows.