Discovery of a spatially and kinematically resolved 55~kpc-scale superbubble inflated by an intermediate redshift non-BAL quasar

TL;DR

This paper reports the discovery of a large, spatially and kinematically resolved superbubble driven by a non-BAL quasar at intermediate redshift, revealing a significant galactic outflow with implications for galaxy evolution.

Contribution

It presents the first spatially and kinematically resolved observation of a superbubble at 55 kpc scale in a non-BAL quasar, combining emission and absorption line analysis.

Findings

Outflow reaches 55 kpc from the quasar nucleus.

Ionized gas mass is approximately 10^8 solar masses.

Outflow kinetic power is insufficient to regulate host galaxy evolution.

Abstract

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 (non-BAL) 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 $R \sim 55$ kpc from the nucleus. The bulk of the ionized gas, with a characteristic mass $M \sim 10^{8}~\rm M_{\odot}$, is blueshifted by $v \approx 700$ km s$^{-1}$ with respect to the quasar systemic velocity. The outflows detected using absorption line and the emission line are likely stratified components of different spatial scale and velocity in the ionized phase outflow. Although feedback in HE 0238$-$1904 is taking place on kpc scale, the kinetic power of the outflow at 55 kpc ($\ll 0.1\% L_{bol}$) implies that it is inadequate to regulate effectively the evolution of the host galaxy at this large scale.