First results from the JWST Early Release Science Program Q3D: Ionization cone, clumpy star formation and shocks in a $z=3$ extremely red quasar host

TL;DR

This JWST study of a $z=3$ quasar host reveals complex interactions including ionization cones, shocks, and intense star formation in a merging, massive galaxy during cosmic noon, highlighting the dynamic processes shaping galaxy evolution.

Contribution

First JWST emission-line study of a $z=3$ quasar host revealing ionization, shocks, and star formation in a merging galaxy with powerful outflows.

Findings

Quasar dominates gas ionization but shocks indicate wide-angle outflows.

Host galaxy shows 1 kpc-scale star-forming clumps with high densities.

Galaxy exhibits high metallicity gradients and extreme star formation conditions.

Abstract

Massive galaxies formed most actively at redshifts $z=1-3$ during the period known as `cosmic noon.' Here we present an emission-line study of an extremely red quasar SDSSJ165202.64+172852.3 host galaxy at $z=2.94$, based on observations with the Near Infrared Spectrograph (NIRSpec) integral field unit (IFU) on board JWST. We use standard emission-line diagnostic ratios to map the sources of gas ionization across the host and a swarm of companion galaxies. The quasar dominates the photoionization, but we also discover shock-excited regions orthogonal to the ionization cone and the quasar-driven outflow. These shocks could be merger-induced or -- more likely, given the presence of a powerful galactic-scale quasar outflow -- these are signatures of wide-angle outflows that can reach parts of the galaxy that are not directly illuminated by the quasar. Finally, the kinematically narrow emission associated with the host galaxy presents as a collection of 1 kpc-scale clumps forming stars at a rate of at least 200 $M_{\odot}$ yr$^{-1}$. The ISM within these clumps shows high electron densities, reaching up to 3,000 cm$^{-3}$ with metallicities ranging from half to a third solar with a positive metallicity gradient and V band extinctions up to 3 magnitudes. The star formation conditions are far more extreme in these regions than in local star-forming galaxies but consistent with that of massive galaxies at cosmic noon. JWST observations reveal an archetypical rapidly forming massive galaxy undergoing a merger, a clumpy starburst, an episode of obscured near-Eddington quasar activity, and an extremely powerful quasar outflow simultaneously.