Parsec-scale properties of GHz-Peaked Spectrum sources from 2.3 and 8.6 GHz VLBI surveys

TL;DR

This study analyzes the parsec-scale structures of 213 GHz-Peaked Spectrum sources using VLBI data, revealing morphological differences between GPS galaxies and quasars and estimating magnetic fields in their cores.

Contribution

It provides a detailed classification of GPS sources' parsec-scale morphology and explores their properties, highlighting exceptions to typical galaxy-quasar morphological relations.

Findings

121 core-dominated sources identified

76 CSO candidates, 24 highly probable

Magnetic field estimated at ~10 mG in cores

Abstract

We investigate the sample of 213 GPS sources selected from simultaneous multi-frequency 1-22 GHz observations obtained with RATAN-600 radio telescope. We use publicly available data to characterize parsec-scale structure of the selected sources. Among them we found 121 core dominated sources, 76 Compact Symmetric Object (CSO) candidates (24 of them are highly probable), 16 sources have complex parsec-scale morphology. Most of GPS galaxies are characterized by CSO-type morphology and lower observed peak frequency (~1.8 GHz). Most of GPS quasars are characterized by "core-jet"-type morphology and higher observed peak frequency (~3.6 GHz). This is in good agreement with previous results. However, we found a number of sources for which the general relation CSO - galaxy, core-jet - quasar does not hold. These sources deserve detailed investigation. Assuming simple synchrotron model of a homogeneous cloud we estimate characteristic magnetic field in parsec-scale components of GPS sources to be B ~ 10 mG.