Gamma-ray-emitting quasar 0202$+$149: a CSS revisited

TL;DR

This paper investigates the properties of the gamma-ray-emitting quasar PKS 0202+149, revealing its classification as a compact steep spectrum source with a re-started nuclear activity and relativistic jet, linking CSS sources to blazar-like gamma-ray behavior.

Contribution

It demonstrates that low-power CSS radio sources can exhibit blazar-like gamma-ray properties, expanding the understanding of AGN classifications and jet activity.

Findings

PKS 0202+149 shows a triple radio structure with a size of ~1.3 kpc.

A relativistic jet with superluminal motion of ~16c is observed.

The source exhibits signs of recent re-started nuclear activity.

Abstract

PKS 0202$+$149 is a low-power radio source with blazar-like $\gamma$-ray AGN characteristics and its properties and classification are investigated in relation to its $\gamma$-ray characteristics. It shows a hint of low frequency turnover at about 200 MHz. Radio imaging data of 0202$+$149 at different frequencies show differing morphologies on both kilo-parsec (kpc) and parsec (pc) scales. The overall source shows a triple structure of core and double lobes with a total projected size of $\sim$1.3 kpc. The compact source structure of 0202+149 is reminiscent of a compact steep spectrum (CSS) source. At pc scales a core-jet structure extends $\sim$25 pc (in projection) at a position angle perpendicular to the kpc-scale structure. The curved pc-scale structure with jet and inner lobe suggests that the CSS nuclear activity has recently re-started although its power has been decreasing, while the kpc-scale lobes are relics of earlier activity. A maximum apparent superluminal motion of $\sim16\,c$ is detected in the jet components, indicating a highly relativistic jet flow. The brightness temperature of the core is lower than the average value found for highly-beamed $\gamma$-ray AGN, indicating a lower radio power and a relatively lower Doppler boosting factor. The CSS radio classification indicates that blazar-like $\gamma$-ray properties can also be manifested in low-power CSS radio sources with appropriate jet and beaming properties.