Probing AGN Feedback in Dwarf Galaxies with Spatially Resolved NIR Coronal Lines from JWST

Archana Aravindan, Thomas Bohn, Gabriela Canalizo, Shobita Satyapal, Vivian U, Weizhe Liu, William Matzko, Sara Doan, Matthew Malkan, Lee Armus, Tohru Nagao, Tanio Diaz-Santos, Aditya Togi, Thomas S. Y. Lai, Sean T. Linden, Marina Bianchin, Yiqing Song, Loreto Barcos-Munoz, Aaron Evans, Hanae Inami, Kirsten Larson, Sabrina Stierwalt, Jason Surace

First listed 2025-12-04 | Last updated 2026-02-16

Abstract

We present the first spatially resolved investigation of near-infrared coronal lines in dwarf galaxies hosting active galactic nuclei (AGN), using JWST/NIRSpec integral field spectroscopy. Coronal lines (CLs), which are forbidden transitions from highly ionized species with ionization potentials up to 450 eV, act as sensitive tracers of the AGN ionizing continuum and feedback processes. Across four dwarf galaxies with ionized gas outflows traced by the optical [O III] lines, we report the detection of 16 unique species of near-infrared CLs. Line ratio diagnostics indicate that photoionization from the AGN dominates the excitation of CLs. We find that the coronal line region in dwarf galaxies, traced by the various CLs, extends up to 0.5 kpc, and can constitute up to 10% of their host galaxy size. Correlations between CL luminosities and [O III] ionized gas outflow properties are consistent with a scenario in which AGN-driven outflows likely facilitate the detection of CLs and contribute to their extent. Several CLs, including [Si VI], [Si VII], and [Mg VIII], exhibit a secondary broad component with W$_{80}$ (the line width enclosing 80% of the total flux)> 300 km/s. If we interpret this spatially compact gas as part of an outflow, this would indicate that the outflowing gas includes a wide range of ionizations. The estimated energetics imply this highly ionized component is compact yet powerful enough to perturb gas in the central regions of the host dwarfs. These results indicate that AGN in low-mass galaxies may produce outflows capable of influencing their structure and evolution.

Short digest

First spatially resolved NIR coronal-line mapping of dwarf AGN with JWST/NIRSpec across four [O III]-outflow hosts detects 16 distinct CL species and finds line ratios dominated by AGN photoionization. The CLR reaches ∼0.5 kpc (up to ≈10% of the galaxy size) and CL luminosities track [O III] outflow properties, implying AGN-driven winds help reveal and extend the highly ionized gas. Several lines, including [Si VI], [Si VII], and [Mg VIII], show a compact secondary broad component with W80 > 300 km/s, indicating outflowing gas spans high ionization states. Energetics suggest this compact, highly ionized phase can perturb central gas in low-mass hosts, supporting meaningful AGN feedback in dwarfs.

Key figures to inspect

• Fig. 1 (KCWI [O III] in J0906): Use the blue wings and W80 within the central 0.5 kpc as the outflow baseline that motivated the JWST CL mapping across the sample.
• Fig. 2 ([Si VI] fits in J0954): Compare one- vs two-component fits for a single spaxel and note the F-test/CHI2RATIO support for a secondary broad CL component; check which other transitions ([Si VII], [Si IX], [Mg IV], [Mg VIII], [Ar VI]) also require it.
• Fig. 3 (CLR maps in J1009): Inspect flux, velocity offset, and W80 of the narrow CL component versus ionization potential to see CLR extent (~few×100 pc), and its orientation roughly perpendicular to the stellar major axis.
• Fig. 4 (Two-component [Si VI] in J0954): The second component is more compact and higher-W80 near the continuum peak, highlighting a centrally concentrated, highly ionized outflow phase.