The gamma-ray emitting radio-loud narrow-line Seyfert 1 galaxy PKS 2004−447

Abstract

Context. -ray-detected radio-loud narrow-line Seyfert 1 (-NLS1) galaxies constitute a small but interesting sample of the -ray-loud AGN. The radio-loudest -NLS1 known, PKS 2004-447, is located in the southern hemisphere and is monitored in the radio regime by the multiwavelength monitoring programme TANAMI. Aims. We aim for the first detailed study of the radio morphology and long-term radio spectral evolution of PKS 2004-447, which are essential for understanding the diversity of the radio properties of -NLS1s. Methods. The TANAMI VLBI monitoring program uses the Australian Long Baseline Array (LBA) and telescopes in Antarctica, Chile, New Zealand, and South Africa to monitor the jets of radio-loud active galaxies in the southern hemisphere. Lower resolution radio flux density measurements at multiple radio frequencies over four years of observations were obtained with the Australia Telescope Compact Array (ATCA).