VLBI Observations of the Gigahertz-Peaked Spectrum Galaxy PKS 1934-638

Abstract

We present 8.4 GHz VLBI observations of the gigahertz-peaked spectrum source PKS 1934-638 made with the Australian Long Baseline Array. Our observations confirm the compact double nature of the source and yield measured separations of 42.7 ± 0.4 mas at epoch 2002 July and 42.6 ± 0.3 mas at epoch 2002 November, which, when combined with previous observations, yield a rate of separation of 23 ± 10 μas yr-1. This result suggests that over a timescale of 32.1 yr, the separation of the two components has changed marginally. Nominally, this provides support to the emerging consensus that compact symmetric objects (CSOs) are young sources. Our measurement of hot spot separation has, to our knowledge, the longest temporal coverage for a CSO reported in the literature.