# VLBI observations of nineteen GHz-Peaked-Spectrum radio sources at 1.6 GHz

## TL;DR

This study uses VLBI at 1.6 GHz to image nineteen GPS radio sources, revealing a high prevalence of compact double-lobe structures indicative of CSOs, and classifying some sources as core-jet types based on morphology.

## Contribution

First VLBI imaging at 1.6 GHz of 17 GPS sources, identifying a high incidence of CSOs and providing new morphological classifications.

## Key findings

- 80% of sources show mini-double-lobe structure
- Six sources classified as CSOs with <1 kpc size
- Three sources identified as core-jet sources

## Abstract

Aims and Methods: We present the results of VLBI observations of nineteen GHz-Peaked-Spectrum (GPS) radio sources at 1.6 GHz. Of them, 15 sources are selected from the Parkes Half Jansky (PHJ) sample (Snellen 2002), 4 others are from our previous observation list. We aimed at imaging the structure of GPS sources, searching for Compact Symmetric Objects (CSOs) and studying the absorption for the convex radio spectra of GPS sources. Results: We obtained total intensity 1.6 GHz VLBI images of 17 sources for the first time. Of them, 80% show mini-double-lobe radio structure, indicating that they are CSOs or candidates, and their host AGNs could be edge-on to us. This result suggests that there is a high incidence of mini double-lobe sources (or CSOs) in the PHJ sample. The sources J0323+0534, J1135-0021, J1352+0232, J2058+0540, J2123-0112 and J2325-0344 with measured redshift, showing double-lobe structure with sizes of <1 kpc, are classified as CSOs. Three sources J1057+0012, J1600-0037 and J1753+2750 are considered as core-jet sources according to their morphologies and flux variability.