Kinematics of the parsec-scale jet of the blazar AO 0235+164

Abstract

Radio interferometric maps of the blazar AO 0235+164 show the existence of a stationary core, and a compact jet composed of multiple receding components. In this work, we determined the structural characteristics of these jet components (core-component distance, position angle, flux density, etc.) using the statistical method for global optimization Cross-Entropy (CE). The images we analyzed were extracted from public databases, totaling 41 images at 15 GHz and 128 images at 43 GHz. Using criteria such as the value of the CE merit function, and mean residuals, we determined the optimum number of components in each map analyzed in this work. We found that jet components are distributed across all four quadrants on the plane of the sky, indicating a possible non-fixed jet orientation during the monitoring interval. The time evolution of the equatorial coordinates of the jet components were used to determine their respective speeds, ejection epochs, and mean position angles on the plane of the sky. We have identified more than 20 components in the jet of AO 0235+164, with their apparent speeds ranging roughly from 2c to 40c, and distributed across all four quadrants on the plane of the sky. From the kinematics of these jet components we could derive a lower limit of about 39 for its bulk jet Lorentz factor and an upper limit of approximately 42 degrees for its jet viewing angle.