Evolution of the pc-scale structure of PKS 1934-638 revisited: first science with the ASKAP and New Zealand telescopes

Abstract

We have studied the archetypal Gigahertz Peaked Spectrum radio galaxy, PKS 1934-638, using the Australian Long Baseline Array, augmented with two new telescopes that greatly improve the angular resolution of the array. These VLBI observations represent the first scientific results from a new antenna in NZ and the first antenna of the Australian SKA Pathfinder (ASKAP). A compact double radio source, PKS 1934-638, has been monitored over a period of 40 years, and the observation described here provides the latest datum, eight years after the previous observation, to aid in the study of the long-term evolution of the source structure. We take advantage of these new long baselines to probe PKS 1934-638 at the relatively low frequency of 1.4 GHz, in order to examine the effects of optical depth on the structure of the radio source. Optical depth effects, resulting in the observation of frequency dependent structure, may have previously been interpreted in terms of an expansion of the source as a function of time. Expansion and frequency dependent effects are important to disentangle in order to estimate the age of PKS 1934-638. We show that frequency dependent structure effects are likely to be important in PKS 1934-638 and present a simple two-dimensional synchrotron source model in which opacity effects due to synchrotron self-absorption are taken into account. Evidence for expansion of the radio source over 40 years is therefore weak, with consequences for the estimated age of the radio source.

arXiv comment18 pages, 5 figures. Accepted for publication in AJ

References in corpus (5)

• DiFX: A software correlator for very long baseline interferometry using multi-processor computing environments
• Science With The Australian Square Kilometre Array Pathfinder
• Proper Motions in Compact Symmetric Objects
• A sample of southern Compact Steep Spectrum radio sources: The VLBI observations
• The Kinematic and Spectral Ages of the Compact Radio Source CTD 93

Cited by in corpus (11)

• The Australian Square Kilometre Array Pathfinder: System Architecture and Specifications of the Boolardy Engineering Test Array
• The second set of pulsar discoveries by CHIME/FRB/Pulsar: 14 Rotating Radio Transients and 7 pulsars
• Spectral Variability of Radio Sources at Low Frequencies
• Dual-Frequency Observations of 140 Compact, Flat-Spectrum Active Galactic Nuclei for Scintillation-Induced Variability
• MUSE 3D Spectroscopy and Kinematics of the gigahertz peaked spectrum Radio Galaxy PKS 1934-63: Interaction, Recently Triggered AGN and Star Formation
• Radio and Gamma-ray Properties of Extragalactic Jets from the TANAMI Sample
• TANAMI - Multiwavelength and Multimessenger Observations of Active Galaxies
• Field sources near the southern-sky calibrator PKS B1934-638: effect on spectral line observations with SKA-MID and its precursors
• First geodetic observations using new VLBI stations ASKAP-29 and WARK12M
• Relighting the fire in Hickson Compact Group (HCG) 15: magnetised fossil plasma revealed by the SKA Pathfinders & Precursors
• The Parsec-Scale Morphology of Southern GPS sources