Investigations on the optical properties and X‐ray emission in compact radio active galactic nuclei

Abstract Compact radio active galactic nuclei (compact radio AGN) are compact (≤20 kpc), powerful radio sources. Currently, the preferred scenario is that they are at the early stage of AGN evolution. At present, the research of compact radio AGN mainly focuses on the radio band; other bands have not been extensively studied. We present the systemic optical properties and X‐ray emission studies for compact radio AGN, to investigate the accretion properties, AGN evolution, and their X‐ray origin. We find that compact radio AGN has various accretion modes indicated by the accretion rate analysis. In the radio power‐linear size diagram, they generally follow the evolutionary trend toward large‐scale radio galaxies with increasing linear size and decreasing accretion rate. Their hard X‐ray emission may be from jet based on the radio/X‐ray relation and fundamental plane of black hole activity.