Resolving the Multiphase Outflow, Shock Signatures, and PAHs in the AGN-Starburst Composite ULIRG F10565+2448 with JWST MIRI/MRS

TL;DR

This study uses JWST MIRI/MRS observations to analyze the complex outflows, shock signatures, and PAH features in the ULIRG F10565+2448, revealing multi-phase outflows and spatially varying PAH properties.

Contribution

First detailed JWST MIRI/MRS spectroscopic analysis of F10565+2448, unveiling multi-phase outflows, shock regions, and PAH variations in an AGN-starburst galaxy.

Findings

Unresolved warm-ionized outflow velocity up to -520 km/s.

Resolved warm-molecular outflow velocity around -280 to -110 km/s.

PAH ionization and grain size vary with radius, indicating complex ISM conditions.

Abstract

We present new James Webb Space Telescope Mid-Infrared Instrument (MIRI) Medium-Resolution Spectrometer (MRS) observations of the nearby ultra-luminous infrared galaxy F10565+2448. These integral field spectroscopic data reveal an unresolved nuclear outflow in both warm-ionized and warm-molecular gas phases as well as a resolved blueshifted kpc-scale warm-molecular outflow. The unresolved warm-ionized outflow has a mean projected velocity up to $-520$ km/s, while the unresolved warm-molecular outflow is slower at $-150$ km/s. For the resolved warm-molecular outflow, the projected mean velocity ($-280 < v_{50} < -110$ km/s) is only slightly faster than the velocity of the disk ($-70 < v_{50} < 120$ km/s) and as such likely does not exceed the estimated escape velocity of $\gtrsim 300$ km/s. The warm-molecular outflow is slightly hotter ($507 \pm 25$K) than the disk ($329 \pm 5$K), and displays areas of higher temperature and lower column density that may indicate a shock front, which we explore using the [Fe II] 5.34 $\mu$m/Pf$\alpha$ shock diagnostic. Analysis of the polycyclic aromatic hydrocarbon features reveal trends of ionization and grain size that first decrease with radius up to 1 kpc before increasing up to 3 kpc. These results bolster the picture of F10565+2448 being an AGN-starburst composite where both star formation and AGN-powered phenomena are required to explain the outflow energetics.