MUSE 3D Spectroscopy and Kinematics of the gigahertz peaked spectrum
  Radio Galaxy PKS 1934-63: Interaction, Recently Triggered AGN and Star
  Formation
  We observe the radio galaxy PKS 1934-63 (at $z=0.1825$) using MUSE (Multi
Unit Spectroscopic Explorer) on the Very Large Telescope (VLT). The radio
source is GigaHertz Peaked Spectrum and compact (0.13 kpc), implying an early
stage of evolution ($\leq 10^4$ yr). Our data show an interacting pair of
galaxies, projected separation 9.1 kpc, velocity difference $\Delta(v)=216$ km
$\rm s^{-1}$. The larger galaxy is a $\rm M_{*}\simeq 10^{11}M_{\odot}$
spheroidal with the emission-line spectrum of a high-excitation young radio
AGN, e.g. strong [OI]6300 and [OIII]5007. Emission-line ratios indicate a large
contribution to the line luminosity from high-velocity shocks ($\simeq 550$ km
$\rm s^{-1}$) . The companion is a non-AGN disk galaxy, with extended $\rm
H\alpha$ emission from which its star-formation rate is estimated as $\rm
0.61~M_{\odot}yr^{-1}$.
  Both galaxies show rotational velocity gradients in $\rm H\alpha$ and other
lines, with the interaction being prograde-prograde. The SE-NW velocity
gradient of the AGN host is misaligned from the E-W radio axis, but aligned
with a previously discovered central ultraviolet source, and a factor 2 greater
in amplitude in $\rm H\alpha$ than in other (forbidden) lines (e.g.
[OIII]5007). This could be produced by a fast rotating (100-150 km $\rm
s^{-1}$) disk with circumnuclear star-formation. We also identify a broad
component of [OIII]5007 emission, blueshifted with a velocity gradient aligned
with the radio jets, and associated with outflow. However, the broad component
of [OI]6300 is redshifted. In spectral fits, both galaxies have old stellar
populations plus $\sim 0.1\%$ of very young stars, consistent with the galaxies
undergoing first perigalacticon, triggering infall and star-formation from
$\sim 40$ Myr ago followed by the radio outburst.
