Discovery of a Spatially and Kinematically Resolved 55 kpc Scale Superbubble Inflated by an Intermediate-redshift Non-BAL Quasar

We report on the discovery of a rare case of spatially and kinematically resolved galactic-scale outflow at intermediate redshift based on VLT/MUSE optical integral field spectroscopic observation of the quasar HE 0238–1904. This classical non–broad absorption line quasar at z = 0.631 remains underexplored in its optical emission lines, though its UV absorption lines are well studied. We identify a superbubble driven by HE 0238−1904 from the emission line morphology, line ratio diagnostics, and kinematics showing a one-sided outflow reaching a projected distance of R ∼ 55 kpc from the nucleus. The bulk of the ionized gas, with a characteristic mass M ∼ 10 ^8 M _⊙ , is blueshifted by v ≈ 700 km s ^−1 with respect to the quasar systemic velocity. The outflows detected using the absorption and emission lines are likely stratified components of different spatial scale and velocity in the ionized phase outflow. Although feedback in HE 0238–1904 is taking place on kiloparsec scales, the kinetic power of the outflow at 55 kpc (≪0.1% L _bol ) implies that it is inadequate to effectively regulate the evolution of the host galaxy at this large scale.