| Description: | Strong radio and gamma-ray emission are characteristics of active galactic nuclei (AGN) which are commonly attributed to blazars and radio galaxies. However, there is a small sample which belongs to a very different population, but which shares some of these properties. These narrow-line Seyfert 1 (gNLSY1) galaxies have received growing attention as they challenge common gamma-ray emission models and are considered to be young AGN, thereby providing a way to study AGN evolution. PKS 2004-447 is a particular fascinating representative as it stands out within the sample of gNLSy1 by having properties consistent with another type of young AGN: compact steep spectrum sources. Due to its location in the southern hemisphere it has been included in the multi-wavelength AGN monitoring program TANAMI (tracking active galactic nuclei with austral milliarcsecond interferometry). As such it has been observed several times at 8.4GHz with the VLBI (Very Long Baseline Interferometry) array utilized by TANAMI. The first observation was presented in Schulz et al. 2016 revealed a single sided mildly relativistic jet with extended diffuse and emission.
Here, we present four new TANAMI observations to investigate the time evolution of the jet. Contrary to the first observation the images show only very faint extended emission close to the detection limit of our observations and almost all of the flux density is located in the compact VLBI core (see Figure). This could be due to the activity of the jet as suggested by small scale variability in the flux density or a lack of sufficient sensitivity or more likely a combination of both. |
