Multi-scale Radio and X-ray Structure of the High-redshift Quasar PMN
  J0909+0354
  The high-redshift quasar PMN J0909+0354 ($z=3.288$) is known to have a
pc-scale compact jet structure, based on global 5-GHz very long baseline
interferometry (VLBI) observations performed in 1992. Its kpc-scale structure
was studied with the Karl G. Jansky Very Large Array (VLA) in the radio and the
Chandra space telescope in X-rays. Apart from the north-northwestern jet
component seen in both the VLA and Chandra images at $2.3''$ separation from
the core, there is another X-ray feature at $6.48''$ in the northeastern (NE)
direction. To uncover more details and possibly structural changes in the inner
jet, we conducted new observations at 5 GHz using the European VLBI Network
(EVN) in 2019. These data confirm the northward direction of the one-sided
inner jet already suspected from the 1992 observations. A compact core and
multiple jet components were identified that can be traced up to $\sim0.25$ kpc
projected distance towards the north, while the structure becomes more and more
diffuse. A comparison with arcsec-resolution imaging with the VLA shows that
the radio jet bends by $\sim30^\circ$ between the two scales. The direction of
the pc-scale jet as well as the faint optical counterpart found for the
newly-detected X-ray point source (NE) favors the nature of the latter as a
background or foreground object in the field of view. However, the extended
($\sim160$ kpc) emission around the positions of the quasar core and NE
detected by the Wide-field Infrared Survey Explorer (WISE) in the mid-infrared
might suggest physical interaction of the two objects.
