The JWST View of Cygnus A: Jet-Driven Coronal Outflow with a Twist

TL;DR

This study uses JWST and Keck spectroscopy to analyze Cygnus A's obscured galaxy, revealing a complex, jet-influenced narrow-line region with rotating and outflowing gas, and detailed multi-phase structures.

Contribution

First detailed infrared spectroscopic analysis of Cygnus A's NLR showing jet-driven multi-phase outflows and rotation, with new insights into the kinematics and physical properties of the region.

Findings

Detection of 169 infrared emission lines revealing complex NLR structure.

Evidence of rotation and outflow in the NLR driven by the radio jet.

High-velocity outflows of 600--2000 km/s from jet-ablated clouds.

Abstract

We present first results from James Webb Space Telescope (JWST) Near-Infrared Spectrograph (NIRSpec), Mid-Infrared Instrument (MIRI), and Keck Cosmic Webb Imager (KCWI) integral field spectroscopy of the powerful but highly obscured host-galaxy of the jetted radio source Cygnus A. We detect 169 infrared emission lines at 1.7--27 micron and explore the kinematics and physical properties of the extended narrow-line region (NLR) in unprecedented detail. The density-stratified NLR appears to be shaped by the initial blow-out and ongoing interaction of the radio jet with the interstellar medium, creating a multi-phase bicone with a layered structure composed of molecular and ionized gas. The NLR spectrum, with strong coronal emission at kpc-scale, is well-modeled by AGN photoionization. We find evidence that the NLR is rotating around the radio axis, perhaps mediated by magnetic fields and driven by angular momentum transfer from the radio jet. The overall velocity field of the NLR is well described by 250 km/s outflow along biconical spiral flow lines, combining both rotation and outflow signatures. There is particularly bright [Fe II] 1.644 micron emission from a dense, high-velocity dispersion, photoionized clump of clouds found near the projected radio axis. Outflows of 600--2000 km/s are found in bullets and streamers of ionized gas that may be ablated by the radio jet from these clouds, driving a local outflow rate of 40 Msun/yr.