Quasi-simultaneous multi-frequency observations of inverted-spectrum GPS candidate sources

TL;DR

This study expands the sample of GPS and HFP radio sources by quasi-simultaneous multi-frequency observations, revealing their compactness and morphology, and demonstrating the effectiveness of data mining for discovering new sources.

Contribution

It introduces a new, larger sample of GPS/HFP candidates and confirms their morphological characteristics using multi-frequency observations and VLBA data.

Findings

45% of sources are GPS or HFP candidates

HFP sources are more compact on milliarcsecond scales

Data mining of SPECFIND database is effective for discovering new sources

Abstract

Gigahertz-Peaked Spectrum (GPS) sources are probably the precursors of local radio galaxies.Existing GPS source samples are small (<200). It is necessary to extend the availabe sample of the Gigahertz-Peaked Spectrum (GPS) and High Frequency Peaker (HFP) sources in order to study their nature with greater details and higher statistical significance. A sample of 214 radio sources, which were extracted from the SPECFIND catalog and show an inverted radio spectrum, were observed quasi-simultaneously at 4.85, 10.45, and 32GHz with the 100-m Effelsberg radio telescope. Using the VLBA calibrator survey (VCS) we have investigated the parsec-scale morphology of the sources. About 45% of the sources in our sample are classified as GPS or HFP candidates. We add 65 new GPS/HFP candidates to existing samples. We confirm the expected tendency that HFP are more compact on milliarcsecond scale than the 'classical' GPS sources, which peak at lower frequencies. The data mining of the SPECFIND database represents a promising tool for the discovery of new GPS/HFP sources.