Structure, spectra and variability of some GPS radio sources

TL;DR

This study uses multifrequency VLBI observations to analyze the structure, spectra, and variability of GPS radio sources, revealing distinct morphological and spectral characteristics between galaxies and quasars, and highlighting variability differences.

Contribution

It provides new high-resolution structural and spectral data on GPS sources and compares long-term variability between GPS galaxies and quasars.

Findings

80% of GPS galaxies show compact double or CSO-like structures.

GPS quasars tend to have core-jet structures.

44% of GPS quasars vary more than 10% over 20 years.

Abstract

We report the results of multifrequency-VLBI observations of GHz-Peaked-Spectrum (GPS) radio sources. The VLBI structure and component spectra of some GPS sources are presented. Our VLBI results show that about 80% of the GPS galaxies exhibit a compact double or CSO-like structure, while the GPS quasars tend to show a core-jet. The component spectra of the GPS galaxies are often steep/convex, and the core has a flat spectrum but it is usually hidden or weak. In addition, we studied the variability of GPS sources by comparing new flux density measures, acquired with the Urumqi 25m telescope at 4.85 GHz, with previous 87GB data. The results show that 44% of the GPS quasars varied higher than 10% in passed 20 years, while the fraction is only 12% for the GPS galaxies meaning that the GPS quasars are much more variable than GPS galaxies. In total, 25% of GPS sources show >10% variability at 4.85 GHz in our sample.