High Frequency GPS sources in the AT20G Survey

TL;DR

This paper presents a new complete sample of high-frequency GPS sources from the AT20G survey, analyzing their properties, redshift distribution, and differences between galaxies and QSOs, with implications for their origin.

Contribution

It introduces a new sample of high-frequency GPS sources with detailed optical and radio properties, extending previous work and providing insights into their intrinsic differences.

Findings

GPS sources are at lower redshift than previous samples.

They have lower 5GHz radio power.

Evidence suggests different origins for GPS spectral shapes in galaxies and QSOs.

Abstract

The Australia Telescope 20GHz (AT20G) survey was used to select a complete sample of 656 Gigahertz Peaked Spectrum (GPS) sources with spectral turnovers above 5GHz. The AT20G has near simultaneous observations at 4.8, 8.6 and 20GHz, which makes it possible to exclude flat spectrum variability as a cause of a source's peaked spectrum. Optical identification of the sample results in 361 QSOs and 104 galaxies and 191 blank fields. Redshifts are known for 104 of the GPS sources. The GPS sources from the AT20G are discussed and compared to previously known samples. The new sample of high frequency peaking GPS sources is found at a lower redshift than previous samples and to also have a lower 5GHz radio power. Evidence is found to support the idea that the origin of the GPS spectral shape are intrinsically different for galaxies and QSOs. This paper is an elaboration and extension of the talk given at the $4^{th}$ CSS/GPS conference in Riccione in May 2008.