Speaker
Description
Our understanding of jet kinematics in z ≥ 3 quasars is still rather limited, based on a sample of less than about 50 objects. We present very long baseline interferometric (VLBI) observations of the powerful blazar J1429+5406 at z=3.015, observed at six frequencies (0.4–15 GHz) between 1994 and 2024. While outer jet components at ∼20–40 milliarcsecond (mas) show no apparent motion, three components within 10 mas exhibit significant proper motions (0.039–0.13) mas/yr, including one that is among the fastest-moving jet components at z ≥ 3 known to date. The core brightness temperature well exceeds the equipartition limit, indicating Doppler boosting. Based on the proper motion of the innermost component, we derive a low jet inclination (within ~5 deg), confirming the blazar nature of the source. Recently, we processed the latest high-sensitivity Very Long Baseline Array measurements of this blazar, taken in 2024. At 1.5 GHz, the radio map clearly reveals a complex, extended radio structure around the source, reaching up to ~400 mas. This resembles a precessing jet whose modeling may constrain its geometry in the future. The data, now based on three decades of observations, are consistent with our previous constraints on the physical parameters of the inner jet. The bulk Lorentz factor appears similar to typical values found in low-redshift blazars. This suggests that there is no fundamental difference between jet physics at low and high redshifts.