Testing adiabatic expansion of shocks in parsec-scale jets by dual-frequency VLBI experiments

TL;DR

This study uses dual-frequency VLBI observations to analyze the spectral properties and brightness temperature evolution of AGN jets, supporting the shock-in-jet model dominated by adiabatic losses.

Contribution

First simultaneous dual-frequency VLBI observations of 12 AGN jets providing insights into shock physics and magnetic field configurations.

Findings

VLBI features' sizes and brightness temperatures align with relativistic shock emission.

Spectral properties support adiabatic loss-dominated shocks.

Discussion of magnetic field orientation effects.

Abstract

We present results of simultaneous dual-frequency (2 GHz and 8 GHz) very long baseline interferometry (VLBI) observations of 12 active galactic nuclei with prominent jets. Spectral properties of the jets and evolution of their brightness temperature are discussed. Measured sizes and brightness temperatures of VLBI features are found to be consistent with emission from relativistic shocks dominated by adiabatic losses. Physical scenarios with different magnetic field orientation in the jets are discussed.